Balloon catheter

Abstract

To provide solutions to conflicting needs to improve an insertion performance of a balloon in a body cavity and to fix the balloon so as not to slip against a body cavity wall in a lesioned part in a narrow part or the like.SOLUTION: There is provided a balloon catheter having a shaft and a balloon body. The balloon body includes a straight pipe part, a distal side tapered part positioned further on a distal side than the straight pipe part, and a proximal side tapered part positioned further on a proximal side than the straight pipe part. The straight pipe part includes a protruding part forming region 41 formed with a protruding part 60 protruding outward in a radial direction of the balloon body and extending in a longitudinal axis direction of the balloon body, and a protruding part non-forming region 42 where the protruding part 60 is not formed. At least a part of the protruding part non-forming region 42 on an outer surface side of the straight pipe part is formed with a hydrophilic coating layer 70. At least a part of the protruding part forming region 41 is not formed with the hydrophilic coating layer 70.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] When a stenosis formed by calcification or the like occurs on the inner wall of a blood vessel, diseases such as angina pectoris and myocardial infarction are caused. As one of the treatments for these, there is an angioplasty in which a stenosis is expanded using a balloon catheter. Angioplasty is a minimally invasive treatment that does not require a thoracotomy such as bypass surgery and is widely performed.

[0003] In angioplasty, it may be difficult to expand a stenosis hardened by calcification or the like with a general balloon catheter. In addition, a method of expanding a stenosis by placing an indwelling expansion device called a stent in the stenosis is also used. However, for example, in some cases, an ISR (In-Stent-Restenosis) lesion or the like may occur in which the neointima of the blood vessel grows excessively after this treatment and the blood vessel stenosis occurs again. In an ISR lesion, the neointima is soft and its surface is slippery, so with a general balloon catheter, the position of the balloon may shift from the lesion during balloon expansion and damage the blood vessel.

[0004] To dilate stenotic lesions such as calcified lesions and ISR lesions, balloon catheters have been developed that have protrusions, blades, or scoring elements on the balloon to engage with the stenotic area. For example, Patent Document 1 discloses a balloon catheter having scoring elements made of a polymer material with higher rigidity than the polymer material forming the balloon body, and in which the scoring elements are flattened at one end and the other end of the balloon. Patent Document 2 discloses a scoring balloon structure in which the height of the scoring elements decreases along the tapered shape of the balloon, and Patent Document 3 discloses a balloon catheter in which an outer protrusion is provided in the straight section of the balloon and an inner protrusion is provided in the tapered section. In Patent Documents 1 to 3, the height of the scoring elements decreases at both ends of the balloon, or an inner protrusion is provided instead of an outer protrusion. In contrast, there are also balloon catheters with high protrusions in which the amount of protrusion of the protrusion located in the distal tapered section is greater than that of the protrusion located in the straight section of the balloon (Patent Document 4). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] U.S. Patent Application Publication No. 2016 / 0128718 [Patent Document 2] Special Publication No. 2014-506140 [Patent Document 3] International Publication No. 2020 / 012851 Brochure [Patent Document 4] International Publication No. 2020 / 012850 Brochure [Overview of the project] [Problems that the invention aims to solve]

[0006] Balloon catheters are inserted into a body cavity in a deflated and folded state and delivered to the treatment site. Therefore, the balloon catheters disclosed in Patent Documents 1 to 3 attempt to improve balloon passability by suppressing the increase in outer diameter by reducing the height of the scoring element at the tip of the balloon to facilitate insertion into the body cavity. Furthermore, in the balloon catheter disclosed in Patent Document 4, when introducing only the tip cone region to the lesion and expanding the balloon, the height of the protrusion located on the tip tapered portion is increased so that the balloon can be expanded while making an incision in the lesion with the element provided on the tip cone region. However, none of these balloons were designed to advance or retract the balloon while it is deflated, allowing for oblique incisions in the stenotic area or incisions over a wide area in a single movement, while also minimizing the effect of reduced passability caused by the scoring element which causes steric obstruction.

[0007] In view of the above circumstances, the present invention aims to provide a balloon catheter that can make an oblique or broad incision of a stenotic area while the balloon is in a deflated state during balloon delivery or when the balloon is delivered to the lesion, and in particular aims to provide a solution to the conflicting needs of improving the ease of balloon insertion within the body cavity and fixing the balloon to the cavity wall so as not to slip at the lesion site such as the stenosis. [Means for solving the problem]

[0008] One embodiment of the balloon catheter of the present invention that can solve the above problems is a balloon catheter having a shaft and a balloon body, wherein the balloon body has a straight tube portion, a distal tapered portion located distal to the straight tube portion, and a proximal tapered portion located proximal to the straight tube portion, the straight tube portion has a protrusion-forming region in which a protrusion is formed that protrudes radially outward from the balloon body and extends in the longitudinal axis direction of the balloon body, and a non-protrusion-forming region in which the protrusion is not formed, and a hydrophilic coating layer is formed on the outer surface of the straight tube portion, at least a part of the non-protrusion-forming region, and a hydrophilic coating layer is not formed on at least a part of the protrusion-forming region.

[0009] In this embodiment, the area without protrusions is basically coated with a hydrophilic coating layer, which improves the ease of inserting the balloon body into the body cavity. Furthermore, since the protrusions are basically not coated with a hydrophilic coating layer, the ability to bite into narrowed areas and the non-slip properties are improved. When the balloon deflates, the area without protrusions (hereinafter sometimes referred to as the "wing portion") is mostly covered, so there is little impact on the ease of inserting the balloon body.

[0010] In the balloon catheter described above, it is preferable that a hydrophilic coating layer is not formed in at least a portion of the extending direction of the straight tube portion, in the region including all of the protruding portion forming area and a portion of the non-protruding portion forming area, and in the boundary region in contact with the protruding portion forming area.

[0011] In the balloon catheter described above, it is preferable that a hydrophilic coating layer is formed in the boundary region between the area where the protrusion is not formed and the area where the protrusion is formed, in a section different from the aforementioned partial section.

[0012] In the balloon catheter described above, a band-shaped hydrophilic coating layer is formed in the region where the protrusion is not formed, with the longitudinal direction being the direction of extension of the straight tube portion. Preferably, the hydrophilic coating layer is thicker at the ends in the width direction than at the center in the width direction.

[0013] In the balloon catheter described above, a band-shaped hydrophilic coating layer is formed in the region where the protruding portion is not formed, with the longitudinal direction being the direction of extension of the straight tube portion. Preferably, the hydrophilic coating layer is thicker at the distal end than at the proximal end.

[0014] Preferably, the balloon catheter has a distal projection on the distal tapered portion that protrudes radially outward from the balloon body and extends in the longitudinal direction of the balloon body, and a proximal projection on the proximal tapered portion that protrudes radially outward from the balloon body and extends in the longitudinal direction of the balloon body, and a band-shaped hydrophilic coating layer is formed on at least one of the distal projection and the proximal projection, with its longitudinal direction being the direction of extension of the balloon body.

[0015] Preferably, the balloon catheter described above has a band-shaped hydrophilic coating layer formed on both the distal and proximal protrusions, with its longitudinal direction being the direction in which the balloon body extends.

[0016] Preferably, the balloon catheter has a band-shaped hydrophilic coating layer formed on the distal projection, with its longitudinal direction being the direction of extension of the balloon body, and no band-shaped hydrophilic coating layer formed on the proximal projection, with its longitudinal direction being the direction of extension of the balloon body.

[0017] In the balloon catheter, a strip-shaped hydrophilic coating layer whose longitudinal direction is the extending direction of the balloon body is formed on the proximal protruding portion, and it is preferable that a strip-shaped hydrophilic coating layer whose longitudinal direction is the extending direction of the balloon body is not formed on the distal protruding portion.

[0018] In the balloon catheter, it is preferable that the surface roughness A (Ra) of the non-protrusion formation region and the surface roughness B (Ra) of the protrusion formation region on the surface of the balloon body satisfy the following formula (1). Surface roughness A (Ra)> Surface roughness B (Ra) - 5 μm ··· (1)

[0019] In the balloon catheter, in a state where the balloon body is contracted, it is preferable that the blade portions formed by the non-protrusion formation region of the straight tube portion cover the protrusions.

[0020] In the balloon catheter, a concave portion is formed in the protrusion in the straight tube portion, and it is preferable that a hydrophilic coating layer is not formed on the inner surface of the concave portion.

[0021] In the balloon catheter, it is preferable that at least a part of the region where the hydrophilic coating layer is not formed in the protrusion formation region has a hydrophobic coating layer.

Effect of the Invention

[0022] According to the balloon catheter, in the non-protrusion formation region, basically, due to the configuration in which the hydrophilic coating layer is formed, when the balloon body is inserted into the body cavity, the insertion property of the balloon body is improved. Further, regarding the protrusions, basically, due to the configuration in which the hydrophilic coating layer is not formed, the biting property and non-slip property into the stenosis portion are improved.

Brief Description of the Drawings

[0023] [Figure 1] It shows a side view of a balloon catheter according to an embodiment of the present invention. [Figure 2] It represents a plan view of the balloon of the balloon catheter shown in FIG. 1 in the expanded state, and shows the protrusion as seen from directly above. [Figure 3] It is a figure showing a radial cross-sectional view of the straight tube portion of the balloon shown in FIG. 2 in the contracted state, and corresponds to the position III-III in FIG. 2. [Figure 4] It is a figure showing a radial cross-sectional view of the straight tube portion of the balloon shown in FIG. 2 in the contracted state, and corresponds to the position IV-IV in FIG. 2. [Figure 5] It is a radial cross-sectional view of the straight tube portion of the balloon shown in FIG. 3 in the contracted state, and shows another embodiment in which the lengths of the blades are different. [Figure 6] (a) is a figure showing a side view of the protrusion according to an embodiment of the present invention, and (b) is a plan view of the protrusion as seen from the top.

Mode for Carrying Out the Invention

[0024] Hereinafter, the present invention will be specifically described based on embodiments. However, the present invention is not limited by the following embodiments, and it is of course possible to appropriately modify and implement it within the range that can conform to the gist of the foregoing and following descriptions, and all of them are included in the technical scope of the present invention. In each drawing, for convenience, hatching, member numbers, etc. may be omitted, but in such cases, reference shall be made to the specification and other drawings. Also, the dimensions of various members in the drawings may differ from the actual dimensions because priority is given to facilitating the understanding of the features of the present invention.

[0025] The balloon catheter in an embodiment of the present invention will be described with reference to Figures 1 to 5. Figure 1 shows a side view of a balloon catheter according to one embodiment of the present invention, and Figure 2 shows a plan view of the balloon catheter shown in Figure 1 in the expanded state, with the protruding portion viewed from directly above. Figure 3 shows a radial cross-sectional view of the straight tube portion of the balloon shown in Figure 2 in the contracted state, corresponding to position III-III in Figure 2. Figure 4 shows a radial cross-sectional view of the straight tube portion of the balloon shown in Figure 2 in the contracted state, corresponding to position IV-IV in Figure 2. Figure 5 is a radial cross-sectional view of the straight tube portion of the balloon shown in Figure 3 in the contracted state, showing another embodiment with a different vane length. Figure 6(a) shows a side view of the protruding portion according to one embodiment of the present invention, and (b) is a plan view of the same protruding portion viewed from the top.

[0026] In this invention, the proximal side refers to the direction toward the user or operator's proximal side with respect to the extending direction of the balloon catheter 1 or the longitudinal axis a of the shaft 3, and the distal side refers to the opposite direction of the proximal side, i.e., the direction toward the person being treated. Even if the member is not a long, slender member like the shaft 3, it has the same longitudinal axis a as the shaft 3. The radial direction b is the direction perpendicular to the longitudinal axis a and connects the center of the balloon body 20 and a point on the circumscribed circle of the balloon body 20 in a cross section perpendicular to the longitudinal axis a. The circumferential direction c is the direction along the circumference of the circumscribed circle of the expanded balloon body 20 in a cross section perpendicular to the longitudinal axis a.

[0027] As shown in Figures 1 and 2, the balloon catheter 1 has a shaft 3 and a balloon 2 provided on the outside of the shaft 3. The balloon catheter 1 has a distal end and a proximal end, with the balloon 2 provided on the distal end of the shaft 3. The balloon catheter 1 is configured so that fluid is supplied to the inside of the balloon 2 through the shaft 3, and the expansion and contraction of the balloon 2 can be controlled using an indefleror (balloon pressurizer). The fluid may be a pressurized fluid pressurized by a pump or the like.

[0028] Preferably, the shaft 3 has a fluid channel inside and also has a guide wire insertion passage. To configure the shaft 3 to have a fluid channel and a guide wire insertion passage inside, for example, the shaft 3 may have an outer tube 31 and an inner tube 32, where the inner tube 32 functions as a guide wire insertion passage and the space between the inner tube 32 and the outer tube 31 functions as a fluid channel. In this configuration where the shaft 3 has an outer tube 31 and an inner tube 32, it is preferable that the inner tube 32 extends from the distal end of the outer tube 31 and penetrates distal to the balloon 2, with the distal side of the balloon 2 joined to the inner tube 32 and the proximal side of the balloon 2 joined to the outer tube 31.

[0029] As shown in Figures 1 and 2, the balloon 2 has a balloon body 20 having an outer surface and an inner surface. The balloon body 20 has a straight tube portion 23, a distal tapered portion 24 located distal to the straight tube portion 23, and a proximal tapered portion 22 located proximal to the straight tube portion 23. The distal tapered portion 24, the straight tube portion 23, and the proximal tapered portion 22 each have a projection 60 that protrudes radially outward from the outer surface of the balloon body 20 and extends in the longitudinal axis direction a of the balloon body 20. The projection 60 has a tip portion 61 in the cross-section of the balloon body 20 in the radial direction b.

[0030] As shown in Figures 1 to 3, a balloon catheter according to one embodiment of the present invention is a balloon catheter 1 having a shaft 3 and a balloon body 20, wherein the balloon body 20 has a straight tube portion 23, a distal tapered portion 24 located distal to the straight tube portion 23, and a proximal tapered portion 22 located proximal to the straight tube portion 23, and the straight tube portion 23 has a protrusion-forming region 41 (see Figure 3) where a protrusion 60 is formed that protrudes radially outward from the balloon body 20 and extends in the longitudinal axis direction of the balloon body 20, and a non-protrusion-forming region 42 (see Figure 3) where the protrusion 60 is not formed, and a hydrophilic coating layer 70 is formed on the outer surface side of the straight tube portion 23, at least a part of the non-protrusion-forming region 42, and the hydrophilic coating layer 70 is not formed on at least a part of the protrusion-forming region 41.

[0031] In this embodiment, the non-protruding region 42 is basically configured to have a hydrophilic coating layer 70, which improves the ease of inserting the balloon body 20 into the body cavity. Furthermore, the surface of the protruding portion 60 is basically not coated with the hydrophilic coating layer 70, which improves its ability to bite into narrowed areas and its non-slip properties. In addition, when the balloon 2 is normally deflated, the protruding portion 60 is generally covered by the non-protruding region 42 (wing-forming portion 28), so there is little impact on reducing the ease of inserting the balloon body 20, allowing the procedure to proceed efficiently.

[0032] As hydrophilic coating agents that can be applied to the balloon body 20, hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, methyl vinyl ether maleic anhydride copolymer, or hydrophilic coating agents made from any combination thereof can be used.

[0033] To selectively create areas where a hydrophilic coating layer 70 is formed and areas where it is not, for example, the areas where the hydrophilic coating layer 70 is not to be formed can be masked in advance with a protective layer (not shown), the balloon body 20 can be dipped in a solution containing a hydrophilic coating agent in that state, and the protective layer can be removed after the solution has dried.

[0034] Preferably, in at least a portion of the extending direction of the straight tube portion 23 of the balloon body 20, the hydrophilic coating layer 70 is not formed in the region that includes all of the protruding portion forming region 41 and a portion of the non-protruding portion forming region 42, and is in contact with the protruding portion forming region 41, and is the region of the boundary portion 43. Since the hydrophilic coating layer 70 is not formed in the region of the boundary portion 43, the non-slip performance of the protruding portion 60 is improved.

[0035] In sections other than the aforementioned partial section, a hydrophilic coating layer may, of course, be formed in the boundary area 43 between the non-protruding portion area 42 and the protruding portion area 41.

[0036] In the non-protruding region 42, a strip-shaped hydrophilic coating layer 70 is formed with its longitudinal direction being the extension direction of the straight tube portion 23. Preferably, the hydrophilic coating layer 70 is thicker at the ends in the width direction than at the center in the width direction. The center in the width direction of the non-protruding region 42 (wing-forming portion 28) becomes the tip of the wing 29 when the balloon body 20 is contracted, so the film thickness is relatively reduced in the center to prevent the hydrophilic coating layer 70 from cracking and peeling off.

[0037] In the non-protruding region 42, a strip-shaped hydrophilic coating layer 70 is formed whose longitudinal direction is the direction of extension of the straight tube portion 23, and it is preferable that the hydrophilic coating layer 70 is thicker at the distal end than at the proximal end. The proximal end of the balloon body 20 is connected to a linear member (not shown) that operates the balloon body 20, and the movement of the linear member makes it a part where bending forces are easily applied to the balloon body 20. To prevent the hydrophilic coating layer 70 from cracking and peeling off in such a part, the film thickness is made relatively lower from the distal end.

[0038] Preferably, the distal tapered portion 24 has a distal projection that protrudes radially outward from the balloon body 20 and extends in the longitudinal direction of the balloon body 20, and the proximal tapered portion 22 has a proximal projection that protrudes radially outward from the balloon body 20 and extends in the longitudinal direction of the balloon body 20, and a band-shaped hydrophilic coating layer (not shown) is formed on at least one of the distal projection and the proximal projection, with its longitudinal direction being the direction of extension of the balloon body. Preferably, the distal tapered portion 24 is a part that tends to hinder insertion of the balloon body 20, and the proximal tapered portion 22 is a part that tends to hinder insertion of the balloon body 20, and the proximal tapered portion 22 is a part that tends to hinder insertion of the balloon body 20, and therefore, it is preferable that a hydrophilic coating layer is formed on it. In particular, it is even more preferable to take any of the following embodiments (1) to (3).

[0039] (1) A band-shaped hydrophilic coating layer is formed on both the distal and proximal protrusions, with its longitudinal direction being the direction of extension of the balloon body.

[0040] By forming a hydrophilic coating layer on the distal projection, insertion is maintained even when there are three-dimensional obstacles. Furthermore, by forming a hydrophilic coating layer on the proximal projection, resistance during balloon removal is reduced.

[0041] (2) The distal protruding portion is formed with a strip-shaped hydrophilic coating layer whose longitudinal direction is the direction of extension of the balloon body, while the proximal protruding portion is not formed with a strip-shaped hydrophilic coating layer whose longitudinal direction is the direction of extension of the balloon body.

[0042] By forming a hydrophilic coating layer on the distal projection, insertion is maintained even in the presence of three-dimensional obstacles. By not forming a hydrophilic coating layer on the proximal projection, the balloon body is less likely to slip against the force pushing it back towards the proximal side when it is advanced into the stenosis and positioned, making positioning easier.

[0043] (3) The proximal projection has a strip-shaped hydrophilic coating layer formed on it, the longitudinal direction of which is the direction of extension of the balloon body, while the distal projection does not have a strip-shaped hydrophilic coating layer formed on it, the longitudinal direction of which is the direction of extension of the balloon body.

[0044] By not forming a hydrophilic coating layer on the distal protrusion, the disadvantage of the balloon body being pushed back proximal and slipping when initially expanded to widen the stenosis opening is reduced. In other words, it is less likely to slip during positioning when pushing and placing it inside the stenosis. Furthermore, forming a hydrophilic coating layer on the proximal protrusion reduces resistance during removal.

[0045] When a notch exists at the distal end of the distal projection or straight tube, or at the proximal end of the proximal projection or straight tube, if a hydrophilic coating film is formed on the notched portion of the projection, the insertion, removal, and cutting force of the balloon body will improve. Conversely, if a hydrophilic coating layer is not formed, the slipperiness of the balloon body will decrease.

[0046] It is preferable that the surface roughness A(Ra) of the non-protruding portion area 42 and the surface roughness B(Ra) of the protruding portion area 41 of the balloon body 20 satisfy the following equation (1).

[0047] Surface roughness A (Ra) > Surface roughness B (Ra) -5 μm ···(1)

[0048] In this way, by keeping the surface roughness A (Ra) of the non-protruding region 41 relatively large, the bonding between the balloon body 20 and the hydrophilic coating layer 70 in the non-protruding region 41 is improved. The surface roughness is the arithmetic mean roughness Ra of the roughness curve on the surface of the balloon body 20 over a reference length. The above arithmetic mean roughness Ra corresponds to the arithmetic mean roughness Ra specified in JIS B 0601 (2001) and is measured in accordance with JIS B 0633 (2001). The reference length is as shown in JIS B 0633 (2001). For measurement, a measuring instrument specified in JIS B 0651 (2001) (for example, a laser microscope manufactured by Keyence Corporation, VK-9510) is used.

[0049] Figure 5 is a radial cross-sectional view of the contracted state of the straight tube portion of the balloon shown in Figure 3, illustrating another embodiment with a different fin length. As shown in Figure 5, when the balloon body 20 is contracted, it is preferable that the fin-forming portion 28, formed by the non-protruding region 42 of the straight tube portion 23, covers the protruding portion 60. Since the protruding portion 60 does not have a hydrophilic coating layer 70, if the tip 61 of the protruding portion 60, which has low slipperiness, is exposed to the outside of the balloon body 20, the insertion of the balloon body 20 will be impaired. However, as shown in Figure 5, when the fins 29 are long, the tip 61 is not exposed to the outside of the balloon body 20, so the insertion of the balloon body is not impaired.

[0050] Figure 6(a) is a side view of a protrusion according to one embodiment of the present invention, and (b) is a plan view of the protrusion viewed from the top. As shown in Figures 6(a) and (b), a recess 62 is formed in the protrusion 60 so as to be cut out from the top. The formation of the recess 62 in the protrusion 60 improves the ease with which the protrusion 60 penetrates the cavity wall of the lesion. Furthermore, by not providing a hydrophilic coating layer on the inner surface 64 of the recess 62, the non-slip properties of the recess 62 are not impaired.

[0051] It is preferable that a hydrophobic coating layer (not shown) is provided on part or all of the area on the protruding portion forming region 41 where the hydrophilic coating layer 70 is not formed (including the inner surface of the recess 64). By providing a hydrophobic coating layer, adhesion between the portion where the hydrophilic coating layer is formed and the lesion is prevented, and the balloon body 20 expands smoothly.

[0052] Examples of hydrophobic coating agents that can be applied to the balloon body 20 include polytetrafluoroethylene (PTFE), fluoroethylene propylene (FEP), silicone oil, hydrophobic urethane resin, carbon coating, diamond coating, diamond-like carbon (DLC) coating, ceramic coating, and substances with low surface free energy terminated with alkyl groups or perfluoroalkyl groups.

[0053] Preferably, the distal tapered portion 24 and the proximal tapered portion 22 are formed so that their diameter decreases as they move away from the straight tube portion 23. Because the balloon body 20 has a straight tube portion 23 that has its maximum diameter when expanded, when the balloon 2 is expanded in a constricted area, the straight tube portion 23 makes sufficient contact with the constricted area, making it easier to expand or cut the constricted area. Furthermore, as will be described later, when the balloon 2 is deflated, wings 29 are formed, but because the balloon body 20 has a distal tapered portion 24 and a proximal tapered portion 22 whose outer diameter decreases as they move away from the straight tube portion 23, when the balloon 2 is deflated and the wings 29 are wrapped around the shaft 3, the protruding portions 60 of the distal tapered portion 24 and the proximal tapered portion 22 can be exposed from the wings 29 of the balloon 2, and these exposed protruding portions 60 can cut the constricted area even when the balloon 2 is deflated.

[0054] As shown in Figures 2 and 3, the protrusion 60 of the balloon 2 is the portion that protrudes radially outward in the direction b from the outer surface of the balloon body 20 when the balloon 2 is in its expanded state. The maximum length of the protrusion 60 that protrudes radially outward in the direction b from the outer surface of the balloon body 20 in a cross-section in the direction b is preferably 1.2 times or more the thickness of the balloon body 20, more preferably 1.5 times or more, and even more preferably 2 times or more, and may also be 100 times or less, 50 times or less, 30 times or less, or 10 times or less. This makes it easier to make an incision of an appropriate depth in the constricted area by the protrusion 60, making the incision easier. Furthermore, such a protrusion 60 makes it possible to improve the strength of the balloon 2 and suppress over-expansion of the balloon 2 when pressurized.

[0055] The number of protrusions 60 in the circumferential direction c of the balloon 2 may be one or multiple, as shown in Figure 3. If the balloon 2 has multiple protrusions 60 in the circumferential direction c, it is preferable that the multiple protrusions 60 are spaced apart in the circumferential direction c, and more preferably that they are arranged at equal intervals in the circumferential direction c. The spacing distance is preferably longer than the maximum circumference of the protrusions 60. When the protrusions 60 are spaced apart in the circumferential direction c and preferably arranged at equal intervals, it becomes easier to fix the balloon 2 and to cut the stenotic portion.

[0056] As shown in Figure 3, the protruding portion 60 has a tip portion 61 in the radial b cross-section of the balloon body 20. The tip portion 61 makes it easier to make an incision in the stenosis, so that the stenosis can be cut while preventing dissection of the vascular intima. The tip portion 61 is the part of the protruding portion 60 that protrudes the furthest outward in the radial b from the outer surface of the balloon body 20, and may have an acute angle as shown in Figure 3, or it may have an obtuse angle, a curved shape, or a flat shape. From the viewpoint of ease of making an incision, it is preferable to have an acute angle. The shape of the protruding portion 60 in the radial b cross-section may be arbitrary, and may be a roughly triangular shape as shown in Figure 3, or it may be a polygon, a sector, a wedge, a convex shape, a spindle shape, etc.

[0057] As shown in Figures 3 to 5, the contracted state of the balloon 2 is the state after fluid has been discharged from inside the balloon 2 or before fluid is supplied to the inside of the balloon 2. In the contracted state of the balloon 2, the inner surface of the balloon body 20 is close to the shaft 3 and the fins 29 are formed. In other words, as shown in Figure 3, the balloon 2 in the expanded state has a fin-forming portion 28 that forms the fins 29 in the contracted state. The embodiments shown in Figures 3 to 5 are embodiments in which the shaft 3 has an outer tube 31 and an inner tube 32, and the balloon 2 has a portion where the inner surface of the balloon body 20 is close to the inner tube 32 in the contracted state. If the distal tapered portion 24 and the proximal tapered portion 22 are gradually reduced in diameter towards the distal and proximal sides, respectively, the length of the fins 29 in the radial direction b in the cross-section in the radial direction b is also gradually shortened towards the distal and proximal sides, respectively, and fins 29 may not be formed in the distal portion of the distal tapered portion 24 and the proximal portion of the proximal tapered portion 22. It is preferable that the wings 29 are not formed at the distal end of the distal tapered portion 24 and the proximal end of the proximal tapered portion 22. If the wings 29 are not formed at the distal end of the distal tapered portion 24 and the proximal end of the proximal tapered portion 22, the protrusion 60 can contact the body cavity wall in those portions without being obstructed by the wings 29, making it possible to incise the stenotic portion.

[0058] Figures 3 to 5 show an configuration with three wings 29, but the number of wings 29 is not particularly limited as long as the balloon 2 can be folded. For example, two or more wings are preferred, three or more are more preferred, and four or more or even five or more wings may be used. If the lower limit of the number of wings 29 is within the above range, the diameter of the balloon 2 can be reduced while covering the protruding portion 60 when folded, making insertion into the body cavity easier. Furthermore, for example, 10 or fewer wings 29 are preferred, 8 or fewer are more preferred, and 6 or fewer are even more preferred. If the upper limit of the number of wings 29 is within the above range, even a balloon 2 with a large diameter can be easily folded. By setting the number of wings 29 within the above range, the size of the portion of the protruding portion 60 covered by the wings 29 in the distal tapered portion 24 and the proximal tapered portion 22 can be adjusted.

[0059] Examples of materials that make up the balloon body 20 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 resin; polyamide resins such as polyamide and polyamide elastomer; fluororesin, silicone resin, and natural rubber such as latex rubber. These may be used individually or in combination of two or more. Among these, polyamide resins, polyester resins, and polyurethane resins are preferably used. In particular, it is preferable to use elastomer resins from the viewpoint of thinning the balloon body 20 and improving its flexibility. For example, among polyamide resins, nylon 12 and nylon 11 are suitable as resins to make up the balloon body 20, and nylon 12 is more preferable because it can be molded relatively easily during blow molding. Furthermore, from the viewpoint of thinning the balloon body 20 and improving its flexibility, polyamide elastomers such as polyether ester amide elastomer and polyamide ether elastomer are preferably used. In particular, polyether ester amide elastomer is preferred because it has a high yield strength and provides good dimensional stability to the balloon body 20.

[0060] It is preferable that the protruding portion 60 is made of the same material as the balloon body 20. If the protruding portion 60 is made of the same material as the balloon body 20, the flexibility of the balloon 2 can be maintained while the protruding portion 60 is less likely to damage the outer surface of the balloon body 20. It is preferable that the balloon body 20 and the protruding portion 60 are integrally molded. This prevents the protruding portion 60 from falling off the balloon body 20.

[0061] Examples of materials that make up the shaft 3 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluororesins, vinyl chloride resins, silicone resins, and natural rubber. These may be used individually or in combination of two or more. In particular, it is preferable that the material making up the shaft 3 be at least one of polyamide resins, polyolefin resins, and fluororesins. This improves the slipperiness of the surface of the shaft 3 and improves the insertion of the balloon catheter 1 into the body cavity.

[0062] The balloon 2 and shaft 3 can be joined by adhesive bonding, welding, or by attaching a ring-shaped member to the overlapping portion of the balloon 2 end and shaft 3 and crimping it. Among these, it is preferable that the balloon 2 and shaft 3 are joined by welding. By welding the balloon 2 and shaft 3, the joint between the balloon 2 and shaft 3 is less likely to come undone even when the balloon 2 is repeatedly expanded and contracted, and the joint strength between the balloon 2 and shaft 3 can be easily increased.

[0063] As shown in Figure 1, the balloon catheter 1 may have a hub 4 on the proximal side of the shaft 3, and the hub 4 may have a fluid injection section 7 that communicates with the fluid passage supplied to the inside of the balloon 2. Furthermore, it is preferable that the hub 4 has a guidewire insertion section 5 that communicates with the guidewire insertion passage. Because the balloon catheter 1 has a hub 4 equipped with a fluid injection section 7 and a guidewire insertion section 5, operations such as supplying fluid to the inside of the balloon 2 to expand and deflate the balloon 2, and operations such as delivering the balloon catheter 1 to the treatment site along the guidewire can be easily performed. Not only is the balloon 2 according to the embodiment of the present invention applicable not only to so-called over-the-wire type balloon catheters in which the guidewire is inserted from the distal side to the proximal side of the shaft 3 as shown in Figure 1, but also to so-called rapid-exchange type balloon catheters in which the guidewire is inserted partway from the distal side to the proximal side of the shaft.

[0064] The shaft 3 and the hub 4 can be joined by, for example, adhesive bonding or welding. Among these, it is preferable that the shaft 3 and the hub 4 are joined by adhesive bonding. By bonding the shaft 3 and the hub 4, the bonding strength between them can be increased, thereby improving the durability of the balloon catheter 1, especially when the materials constituting the shaft 3 and the hub 4 are different, such as when the shaft 3 is made of a highly flexible material and the hub 4 is made of a highly rigid material. [Explanation of Symbols]

[0065] 1: Balloon catheter 2: Balloon 3: Shaft 4: Hub 5: Guide wire insertion section 7:Fluid injection part 20: Balloon body 22: Proximal tapered section 23: Straight pipe section 24: Distal tapered section 28: Feather forming section 29: Feather 31: Outer tube 32: Inner tube 41:Protrusion formation area 42:Protrusion non-formation area 43: Boundary 60:Protrusion 61:Tip 62: Recess 64: Inner surface of recess 70: Hydrophilic coating layer a: Longitudinal axis b: radial direction c: Circumferential direction

Claims

1. A balloon catheter having a shaft and a balloon body, The balloon body has a straight tube section, a distal tapered section located distal to the straight tube section, and a proximal tapered section located proximal to the straight tube section. The straight tube portion has a protruding portion forming region in which a protruding portion is formed that protrudes radially outward from the balloon body and extends in the longitudinal direction of the balloon body, and a non-protruding portion forming region in which no protruding portion is formed. On the outer surface of the straight pipe portion, a hydrophilic coating layer is formed on at least a portion of the area where the protrusion is not formed, and a hydrophilic coating layer is not formed on at least a portion of the area where the protrusion is formed. In the region where the protrusion is not formed, the main body is a strip whose longitudinal direction is the direction in which the straight pipe extends. A water-based coating layer is formed, and the hydrophilic coating layer is thicker at the edges in the width direction than at the center in the width direction. In the contracted state of the balloon body, the non-protruding region of the straight tube portion The formed wing portion covers the protruding portion, The center of the region where the protrusion is not formed in the width direction is the balloon catheter that becomes the tip of the wing when the balloon body is deflated.

2. The balloon catheter according to claim 1, wherein in at least a portion of the extending direction of the straight tube portion, a hydrophilic coating layer is not formed in the boundary region that includes the entirety of the protruding portion forming area and a portion of the non-protruding portion forming area and is in contact with the protruding portion forming area.

3. The balloon catheter according to claim 2, wherein a hydrophilic coating layer is formed in the boundary region between the region where the protrusion is not formed and the region where the protrusion is formed, in a section different from the aforementioned partial section.

4. The balloon catheter according to claim 2 or 3, wherein in the region where the protrusion is not formed, a band-shaped hydrophilic coating layer is formed whose longitudinal direction is the direction of extension of the straight tube portion, and the hydrophilic coating layer is thicker at the distal end than at the proximal end.

5. The distal tapered portion has a distal projection that protrudes radially outward from the balloon body and extends in the longitudinal direction of the balloon body. The proximal tapered portion has a proximal projection that protrudes radially outward from the balloon body and extends in the longitudinal direction of the balloon body. The balloon catheter according to any one of claims 1 to 4, wherein a band-shaped hydrophilic coating layer is formed on at least one of the distal protrusion and the proximal protrusion, the longitudinal direction of which is the direction of extension of the balloon body.

6. Both the distal and proximal protrusions have a longitudinal direction that is aligned with the extension of the balloon body. The balloon catheter according to claim 5, wherein a band-shaped hydrophilic coating layer is formed in a direction.

7. The balloon catheter according to claim 5, wherein a band-shaped hydrophilic coating layer is formed on the distal projection, with its longitudinal direction being the direction of extension of the balloon body, and a band-shaped hydrophilic coating layer is not formed on the proximal projection, with its longitudinal direction being the direction of extension of the balloon body.

8. The balloon catheter according to claim 5, wherein a band-shaped hydrophilic coating layer is formed on the proximal projection, the longitudinal direction of which is the direction of extension of the balloon body, and the distal projection is not formed with a band-shaped hydrophilic coating layer whose longitudinal direction is the direction of extension of the balloon body.

9. The balloon catheter according to any one of claims 1 to 8, wherein a recess is formed in the protruding portion of the straight tube portion, and a hydrophilic coating layer is not formed on the inner surface of the recess.

10. The balloon catheter according to any one of claims 1 to 9, wherein at least a portion of the region where the protrusion is formed and where the hydrophilic coating layer is not formed is covered with a hydrophobic coating layer.

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