Balloon catheter

Abstract

Provided is a solution for conflicting needs between improving ease in insertion of a balloon into a body cavity and fixing a balloon to a cavity wall so as not to slide thereon at a lesion, such as at a narrow portion.　This balloon catheter has a shaft and a balloon body. The balloon body comprises a straight tube part, a distal-side tapered part, and a proximal-side tapered part. The straight tube part has a protrusion formed area (41) which has a protrusion (60) formed therein and a protrusion not-formed area (42) in which a protrusion (60) is not formed. A hydrophilic coating layer (70) is formed at a boundary part (43) that encompasses a portion of the protrusion formed area (41) and a portion of the protrusion not-formed area (42). The hydrophilic coating layer (70) is not formed in at least a portion of an area that is in the protrusion formed area (41) but that is outside the boundary area (43).

Description

Technical Field

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

Background Art

[0002] When a stenosis hardened by calcification or the like is formed on the inner wall of a blood vessel, diseases such as angina pectoris and myocardial infarction are caused. As one of these treatments, there is an angioplasty in which a stenosis is expanded using a balloon catheter. Angioplasty is a minimally invasive treatment that does not require 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 the 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 Initiative] [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 solution to the conflicting needs of improving the ease of inserting a balloon within a body cavity and ensuring that the balloon is securely fixed to the cavity wall in lesions such as stenoses, and also aims to ensure that the base of the protruding portion reliably reaches lesions such as stenoses. [Means for solving the problem]

[0008] One embodiment of the balloon catheter of the present invention that can solve the above problems is as follows. [1] A balloon catheter having a shaft and a balloon body, wherein the balloon body has a straight section, a distal tapered section located distal to the straight section, and a proximal tapered section located proximal to the straight section, and the straight section has a projection-forming region where a projection is formed that protrudes radially outward from the balloon body and extends in the longitudinal direction of the balloon body, and a non-projection-forming region where no projection is formed (hereinafter sometimes referred to as the "wing-forming region"), and a hydrophilic coating layer is formed on the boundary portion of the outer surface of the straight section that includes a part of the projection-forming region and a part of the non-projection-forming region in at least a portion of the projection-forming region that is not the boundary portion, and the hydrophilic coating layer is not formed on at least a portion of the projection-forming region that is not the boundary portion.

[0009] In the balloon catheter according to the above embodiment of the present invention, as the balloon expands, the protruding portion cuts through the narrowed portion and penetrates it. In the final stage, when the base of the protruding portion enters the narrowed portion, the resistance to pushing the protruding portion increases, making it difficult for the protruding portion to penetrate. However, by providing slipperiness to the base of the protruding portion, it becomes possible to penetrate all the way to the base of the protruding portion.

[0010] The balloon catheter according to the embodiment of the present invention is preferably one of the following [2] to

[16] . [2] In the region where no protrusion is formed, a band-shaped hydrophilic coating layer is formed whose longitudinal direction is the direction of extension of the straight tube, and the hydrophilic coating layer is thicker at the ends in the width direction than at the center in the width direction, as described in [1].

[0011] [3] In the region where no protrusion is formed, a band-shaped hydrophilic coating layer is formed whose longitudinal direction is the direction of extension of the straight tube, and the hydrophilic coating layer is thicker distally than proximal, as described in [1] or [2].

[0012] [4] The straight tube portion has, in the direction of extension, a distal section, a central section, and a proximal section in that order, and in the central section, a hydrophilic coating layer is formed at the boundary between the protrusion-forming region and the non-protrusion-forming region, in the region from the protrusion-forming region to the non-protrusion-forming region, and in the distal section and the proximal section, there is a region from the protrusion-forming region to the non-protrusion-forming region in which the hydrophilic coating layer is not formed. The balloon catheter according to any one of [1] to [3].

[0013] [5] A balloon catheter according to any one of [1] to [3], wherein at least one of the distal tapered portion and the proximal tapered portion has a projection that protrudes radially outward from the balloon body and extends in the longitudinal direction of the balloon body, and there exists a transition region in which the height decreases from the projection of the straight tube portion to the projection of the tapered portion, and a hydrophilic coating layer continuous with the hydrophilic coating layer of the straight tube portion is formed in at least a portion of the transition region.

[0014] [6] The balloon catheter according to any one of [1] to [5], wherein 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, and 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, 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] [7] The balloon catheter according to [6], wherein a band-shaped hydrophilic coating layer is formed on both the distal projection and the proximal projection, with its longitudinal direction being the direction of extension of the balloon body.

[0016] [8] A strip-shaped hydrophilic coating layer with its longitudinal direction being the extending direction of the balloon body is formed on the distal protrusion, and a strip-shaped hydrophilic coating layer with its longitudinal direction being the extending direction of the balloon body is not formed on the proximal protrusion. The balloon catheter according to [6].

[0017] [9] A strip-shaped hydrophilic coating layer with its longitudinal direction being the extending direction of the balloon body is formed on the proximal protrusion, and a strip-shaped hydrophilic coating layer with its longitudinal direction being the extending direction of the balloon body is not formed on the distal protrusion. The balloon catheter according to [6].

[0018]

[10] There is a transition region with a decreasing height from the protrusion of the straight tube portion to the protrusion of the tapered portion provided with the strip-shaped hydrophilic coating layer. In at least a partial section of the transition region, a hydrophilic coating layer continuous with the strip-shaped hydrophilic coating layer is formed. The balloon catheter according to any one of [6] to [9].

[0019]

[11] Among the surfaces of the balloon body, the surface roughness A (Ra) of the non-protrusion formation region and the surface roughness B (Ra) of the protrusion formation region satisfy the following formula (1). The balloon catheter according to any one of [1] to

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

[0020]

[12] In the state where the balloon body is contracted, the blade formation portion formed by the non-protrusion formation region of the straight tube portion covers the protrusion. The balloon catheter according to any one of [1] to

[11] .

[0021]

[13] In the straight tube portion, a concave portion is formed in the protrusion, and the highest end of the hydrophilic coating layer formed on the protrusion is at the same height as the bottommost part of the concave portion or at a position higher than the bottommost part of the concave portion. The balloon catheter according to any one of [1] to

[12] .

[0022]

[14] In the straight tube portion, a concave portion is formed in the protruding portion, and the highest end of the hydrophilic coating layer formed on the protruding portion is located at a position lower than the bottommost portion of the concave portion. The balloon catheter according to any one of [1] to

[12] .

[0023]

[15] In the straight tube portion, a concave portion is formed in the protruding portion, and the surface roughness C(Ra) of the bottom surface of the concave portion is larger than the surface roughness D(Ra) of the top surface of the protruding portion. The balloon catheter according to

[11] or

[12] .

[0024]

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

[15] , having a hydrophobic coating layer on at least a part of the region where the hydrophilic coating layer is not formed in the protruding portion forming region.

Advantages of the Invention

[0025] According to the above balloon catheter, the balloon has non-slip performance, and when the protruding portion penetrates by splitting the stenosis as the balloon expands, at the final stage where the root of the protruding portion enters the stenosis, although the resistance to the pushing of the protruding portion increases and it becomes difficult for the protruding portion to penetrate, by providing slipperiness at the root of the protruding portion, it becomes easier to penetrate to the root of the protruding portion.

Brief Description of the Drawings

[0026] [Figure 1] It shows a side view of the balloon catheter according to an embodiment of the present invention. [Figure 2] It shows a plan view of the balloon in the expanded state of the balloon catheter shown in FIG. 1, as seen directly from above the protruding portion. [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, corresponding 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, corresponding to the position IV-IV in FIG. 2. [Figure 5] Figure 4 is a radial cross-sectional view of the contracted straight tube section of the balloon, showing another embodiment with different fin lengths. [Figure 6] This figure shows the side view of the protrusion formed on the straight tube section of the balloon shown in Figure 2. [Figure 7] This figure shows another example of the side view of the projection formed on the straight tube section of the balloon shown in Figure 2. [Figure 8] This figure shows the protruding portion shown in Figure 6, and the distal tapered portion and the protruding portion of the protruding [Modes for carrying out the invention]

[0027] The present invention will be described in detail below based on embodiments, but the present invention is not limited to the embodiments described below, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component reference numerals may be omitted in the drawings for convenience, in which case please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority has been given to helping to understand the features of the present invention.

[0028] A balloon catheter in an embodiment of the present invention will be described with reference to Figures 1 to 8. 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 4 in the contracted state, showing another embodiment with a different vane length. Figures 6 and 7 show side views of the protruding portion formed on the straight tube portion of the balloon shown in Figure 2. Figure 8 shows the protruding portion shown in Figure 6, and the distal tapered portion and proximal tapered portion protruding portions that are continuous in the extending direction from the protruding portion, showing an embodiment in which a band-shaped hydrophilic coating layer whose longitudinal direction is the extending direction of the balloon body is formed on the distal and proximal protruding portions.

[0029] 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 x 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, rectangular member like the shaft 3, it has the same longitudinal axis x as the shaft 3. The radial direction y is the direction perpendicular to the longitudinal axis x and is the direction connecting the center of the balloon body 20 and a point on the outer edge of the balloon body 20 in a cross section perpendicular to the longitudinal axis x. The circumferential direction z 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 x.

[0030] 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.

[0031] 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, as shown in Figure 1, the balloon catheter 1 is an over-the-wire type having a guide wire insertion passage extending from the distal to the proximal side of the shaft 3, and the shaft 3 has an outer tube 31 and an inner tube 32, with the inner tube 32 functioning as the guide wire insertion passage and the space between the inner tube 32 and the outer tube 31 functioning 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.

[0032] Alternatively, although not shown in the figures, a balloon catheter 1 according to an embodiment of the present invention may be a rapid exchange type having a guidewire port midway from the distal to the proximal end of the shaft, and a guidewire insertion passage provided from the guidewire port to the distal end of the shaft. In this case, the balloon catheter preferably has an outer shaft and an inner shaft that functions as a guidewire insertion passage, and it is preferable that the space inside the outer shaft and outside the inner shaft functions as a fluid flow path. It is preferable that the inner shaft extends from the distal end of the outer shaft and penetrates the balloon, with the distal end of the balloon connected to the inner shaft and the proximal end of the balloon connected to the outer shaft.

[0033] 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 straight tube portion 23 has a projection 60 that protrudes radially y outward from the outer surface of the balloon body 20 and extends in the longitudinal axis direction x 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 y. As will be described later, the distal tapered portion 24 and / or the proximal tapered portion 22 may also have projections 60.

[0034] 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 outward in the radial direction y of the balloon body 20 and extends in the longitudinal axis direction x of the balloon body 20, and a non-protrusion-forming region 42 (see Figure 3) where a protrusion 60 is not formed, and a hydrophilic coating layer 70 is formed on a boundary portion 43 that is on the outer surface side of the straight tube portion 23 and includes a part of the protrusion-forming region 41 and a part of the non-protrusion-forming region 42 in at least a portion of the extending direction of the straight tube portion 23, and the hydrophilic coating layer 70 is not formed on a part or all of the area of ​​the protrusion-forming region 41 that is not the boundary portion 43. There are no particular restrictions on the width of the protruding portion forming region 41 that is not the boundary portion 43 (i.e., the region where the hydrophilic coating layer 70 is not formed), but when the length in the circumferential direction z on the surface of the protruding portion forming region 41 is taken as 100%, it can be, for example, 70% or less, 50% or less, or 30% or less.

[0035] In this embodiment, the balloon body 20 has non-slip properties, and as the balloon body 20 expands, the protrusion 60 cuts through the constricted area and penetrates it. In the final stage, when the base of the protrusion 60 enters the constricted area, the resistance to pushing the protrusion 60 increases, making it difficult for the protrusion 60 to penetrate. However, by providing a hydrophilic coating layer 70 at the base of the protrusion 60, it is made slippery, making it easier for the protrusion 60 to penetrate the lesion up to its base.

[0036] 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.

[0037] To selectively create areas where the 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. Alternatively, the hydrophilic coating layer 70 may be formed by applying or covering with a coating agent.

[0038] The straight tube section 23 has a distal section, a central section, and a proximal section in the direction of extension. In the central section, a hydrophilic coating layer 70 is formed at the boundary 43 between the protrusion-forming region 41 and the non-protrusion-forming region 42, extending from the protrusion-forming region 41 to the non-protrusion-forming region 42. In the distal and proximal sections, it is preferable to have a configuration in which the hydrophilic coating layer 70 is not formed at the boundary 43 between the protrusion-forming region 41 and the non-protrusion-forming region 42, extending from the protrusion-forming region 41 to the non-protrusion-forming region 42. With this configuration, the central section of the balloon body 20 can be set at the position of the constriction, and the distal section of the straight tube section 23 can securely fix the area near the exit of the constriction, and the proximal section of the straight tube section 23 can securely fix the area near the entrance of the constriction. The proportion of the distal section, central section, and proximal section is arbitrary, but the length of the central section is preferably 40% to 70% of the length of the straight tube section 23.

[0039] As described above, a hydrophilic coating layer 70 is basically formed on the boundary portion 43 of the balloon body 20. However, in a portion of the extension direction of the straight tube portion 23, there may be a portion where the hydrophilic coating layer 70 is not formed in the boundary portion 43 between the protruding portion forming region 41 and the non-protruding portion forming region 42. In such a portion, the absence of the hydrophilic coating layer 70 improves the non-slip performance of the balloon body 20.

[0040] 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.

[0041] 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 section 23. Preferably, 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 10, and is therefore susceptible to bending forces acting on the balloon body 20 depending on the movement of the linear member. To prevent the hydrophilic coating layer 70 from cracking and peeling off in such areas, the film thickness is relatively lower at the distal end. Here, the strip-shaped hydrophilic coating layer 70 is a hydrophilic coating layer 70 that has a predetermined width in the circumferential direction z of the balloon body 20 and extends in the longitudinal axis direction x. Figure 6, described later, shows the strip-shaped hydrophilic coating layer 70 in the straight tube section 23 where the recess 62 is formed, but the strip-shaped hydrophilic coating layer 70 in the non-protruding region 42 can be understood similarly.

[0042] Preferably, the distal tapered portion 24 has a distal projection (i.e., a projection 60 provided on the distal tapered portion 24) that protrudes outward in the radial direction y of the balloon body 20 and extends in the longitudinal axis direction x of the balloon body 20, and the proximal tapered portion 22 has a proximal projection (i.e., a projection 60 provided on the proximal tapered portion 22) that protrudes outward in the radial direction y of the balloon body 20 and extends in the longitudinal axis direction x of the balloon body 20, and a strip-shaped hydrophilic coating layer 70 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 20. The strip-shaped hydrophilic coating layer 70 on the distal projection and the proximal projection can be provided, for example, as shown in Figure 8. Figure 8 shows an embodiment in which a band-shaped hydrophilic coating layer 70 is provided on both the distal and proximal protrusions, but the band-shaped hydrophilic coating layer 70 may be provided on either the distal or proximal protrusion. 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, so it is preferable that a hydrophilic coating layer be formed thereon. In particular, it is even more preferable to adopt one of the following embodiments (1) to (3).

[0043] (1) A band-shaped hydrophilic coating layer 70 is formed on both the distal and proximal protrusions, with its longitudinal direction being the direction of extension of the balloon body 20.

[0044] By forming a hydrophilic coating layer on the distal protrusion, insertion is maintained even when there are three-dimensional obstacles. Furthermore, by forming a hydrophilic coating layer on the proximal protrusion, resistance during the removal of the balloon body 20 can be reduced.

[0045] (2) The distal protruding portion is formed with a strip-shaped hydrophilic coating layer 70 whose longitudinal direction is the direction of extension of the balloon body 20, while the proximal protruding portion is not formed with a strip-shaped hydrophilic coating layer 70 whose longitudinal direction is the direction of extension of the balloon body 20.

[0046] By forming a hydrophilic coating layer on the distal protrusion, insertion is maintained even in the presence of three-dimensional obstacles. By not forming a hydrophilic coating layer on the proximal protrusion, when the balloon body 20 is advanced into the stenosis and positioned, the balloon body is less likely to slip against the force pushing it back towards the proximal side, making positioning easier.

[0047] (3) The proximal projection has a strip-shaped hydrophilic coating layer 70 formed on it, the longitudinal direction of which is the direction of extension of the balloon body 20, while the distal projection does not have a strip-shaped hydrophilic coating layer 70 formed on it, the longitudinal direction of which is the direction of extension of the balloon body 20.

[0048] By not forming a hydrophilic coating layer on the distal protrusion, the disadvantage of the balloon body 20 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.

[0049] When a notch exists at the distal end of the distal projection or the straight tube portion 23, or at the proximal end of the proximal projection or the straight tube portion 23, 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 be improved. Conversely, if a hydrophilic coating layer is not formed, the slipperiness of the balloon body 20 will be reduced.

[0050] 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).

[0051] Surface roughness A (Ra) > Surface roughness B (Ra) -5 μm ···(1)

[0052] In this way, by keeping the surface roughness A (Ra) of the non-protruding region 42 relatively large, the bonding between the balloon body 20 and the hydrophilic coating layer 70 in the non-protruding region 42 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 B0601 (2001) and is measured in accordance with JIS B0633 (2001). The reference length is as shown in JIS B0633 (2001). For measurement, a measuring instrument specified in JIS B0651 (2001) (for example, a laser microscope manufactured by Keyence Corporation, VK-9510) is used.

[0053] Figure 5 is a cross-sectional view in the radial direction y of the contracted state of the straight tube portion 23 of the balloon shown in Figure 4, and shows another embodiment with a different length of fins 29. 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 poor. However, when the fins 29 are long as shown in Figure 5, the tip 61 is not exposed to the outside of the balloon body 20, so the insertion of the balloon body 20 is not impaired.

[0054] Figure 6 shows a side view of the protrusion 60 formed on the straight pipe section 23. In Figure 6, the hatched areas indicate the region where the hydrophilic coating layer 70 is present, not a cross-section. The protrusion 60 has one or more recesses 62 formed therein, which enhances its ability to penetrate the lesion. Here, it is desirable that the highest end 71 of the hydrophilic coating layer 70 formed on the protrusion 60 be at the same height as the lowest end 63 of the recess 62, or higher than the lowest end 63 of the recess 62. This is because the lowest end 63 of the recess 62 tends to create resistance when cutting into the lesion, so having the hydrophilic coating layer 70 near the lowest end 63 or higher makes it easier for the protrusion 60 to penetrate to the base.

[0055] Figure 7 shows a side view of the protrusion 60 formed on the straight pipe section 23. In Figure 7, the hatched areas indicate the region where the hydrophilic coating layer 70 is present, not a cross-section. The protrusion 60 has a recess 62 formed on it, similar to Figure 6. It is desirable that the highest end 71 of the hydrophilic coating layer 70 formed on the protrusion 60 is lower than the lowest end 63 of the recess 62. Since the lowest end 63 of the recess 62 is a place that is likely to get caught on biological tissue, it is desirable to avoid coating this area in order to provide non-slip properties.

[0056] Figure 8 shows the projection 60 shown in Figure 6 and the projections 60 of the distal tapered portion 24 and the proximal tapered portion 22 that are continuous in the direction extending from the projection 60. As shown in Figure 8, at least one of the distal tapered portion 24 and the proximal tapered portion 22 has a projection 60 that protrudes outward in the radial direction y of the balloon body 20 and extends in the longitudinal axis direction x of the balloon body 20, and there is a transition region 65 in which the height decreases from the projection 60 of the straight tube portion 23 to the projection 60 of the distal tapered portion 24 and / or the proximal tapered portion 22. The presence of the transition region 65 prevents the catheter from getting caught and improves catheter insertion. In addition, a hydrophilic coating layer continuous with the hydrophilic coating layer 70 of the straight tube portion 23 is formed in part or all of the transition region 65. This makes it possible to further reduce the resistance to pushing in the projection 60 when cutting through the stenosis and entering. Furthermore, in part or all of the transition region 65, a continuous hydrophilic coating layer is formed with the band-shaped hydrophilic coating layer formed on the protruding portion 60 of the distal tapered portion 24 and / or the proximal tapered portion 22. This further improves catheter insertion.

[0057] In the balloon catheter 1, it is preferable that the surface roughness C(Ra) of the bottom of the recess 62 is greater than the surface roughness D(Ra) of the tip 61 of the protrusion 60. The recess 62 can be formed by irradiating the protrusion 60 with laser light, and the surface of the bottom of the recess 62 formed by laser light irradiation will be rougher than the surface of the tip 61. This surface roughness can improve the non-slip properties of the recess 62. On the other hand, a hydrophilic coating layer 70 can also be formed on the surface of the bottom of the recess 62, in which case the presence of the hydrophilic coating layer 70 makes it easier for the protrusion 60 to penetrate to its base. In addition, the hydrophilic coating layer 70 adheres more easily to the rough bottom surface.

[0058] It is preferable to have a hydrophobic coating layer (not shown) on part or all of the area on the protruding portion forming region 41 where the hydrophilic coating layer 70 is not formed. By providing a hydrophobic coating layer, adhesion between the portion where the hydrophilic coating layer 70 is formed and the lesion is prevented, and the balloon 2 expands smoothly. The hydrophobic coating layer can also be formed in the same way as the hydrophilic coating layer 70.

[0059] 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.

[0060] The coating agent may contain chemicals or additives.

[0061] The straight tube section 23 preferably has the same diameter in the longitudinal axis x and is cylindrical in shape, and the distal tapered section 24 and the proximal tapered section 22 preferably have a conical or frustoconical shape, with the diameter decreasing as they move away from the straight tube section 23. Because the balloon body 20 has a straight tube section 23 that has the maximum diameter when expanded, when the balloon 2 is expanded in a stenosis, the straight tube section 23 makes sufficient contact with the stenosis, making it easier to expand or incise the stenosis. Furthermore, as will be described later, when the balloon 2 is deflated, wings 29 are formed. However, because the balloon body 20 has a distal tapered section 24 and a proximal tapered section 22 whose outer diameter decreases as they move away from the straight tube section 23, when the balloon 2 is deflated and the wings 29 are wrapped around the shaft 3, the protruding portions 60 at the distal tapered section 24 and the proximal tapered section 22 can be exposed from the wings 29 of the balloon 2. These exposed protruding portions 60 allow the narrowed portion to be cut even when the balloon 2 is deflated.

[0062] As shown in Figures 2 and 3, the protrusion 60 of the balloon 2 is the portion that protrudes radially outward in the y direction from the outer surface of the balloon body 20. The maximum length of the protrusion 60 that protrudes radially outward in the y direction from the outer surface of the balloon body 20 in a cross-section in the radial y direction 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 is also acceptable to 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.

[0063] The number of protrusions 60 in the circumferential direction z 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 z, it is preferable that the multiple protrusions 60 are spaced apart in the circumferential direction z, and more preferably that they are arranged at equal intervals in the circumferential direction z. 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 z and preferably arranged at equal intervals, it becomes easier to fix the balloon 2 and to cut the stenotic portion.

[0064] As shown in Figure 3, the protruding portion 60 has a tip portion 61 in the cross-section of the balloon body 20 in the radial direction y. 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 direction y 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 cross-section in the radial direction y may be arbitrary, and may be a roughly triangular shape as shown in Figure 3, or for example, a triangle, quadrilateral, polygon, semicircle, part of a circle, roughly circular, sector, wedge, convex shape, spindle shape, and combinations thereof. Furthermore, triangles, quadrilaterals, and polygons include not only those with clearly defined corner vertices and straight edges, but also so-called rounded polygons with rounded corners, and those with at least a portion of their edges being curved. Alternatively, the cross-sectional shape of the protruding portion 60 may be an irregular shape with irregularities, indentations, or other defects.

[0065] 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 y direction in the cross-section in the radial y direction will also gradually decrease 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.

[0066] 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, ten or fewer wings 29 are preferred, eight or fewer are more preferred, and six 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.

[0067] Although not shown in the figures, balloon 2 may have an inner projection that protrudes radially inward in the y-direction from the inner surface of the balloon body 20. Preferably, the projection 60 and the inner projection are located at the same position in the circumferential z-direction.

[0068] 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.

[0069] 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. Furthermore, if an inner protruding portion is provided, it is preferable that the inner protruding portion is also made of the same material as the balloon body 20 and is integrally molded with the balloon body 20. Alternatively, the material forming the protruding portion 60 and the inner protruding portion may be different from the material forming the balloon body 20, as long as it has a certain degree of compatibility with the material forming the balloon body 20.

[0070] The shaft 3 is preferably composed of resin, metal, or a combination of resin and metal. Using resin as the constituent material of the shaft 3 makes it easier to impart flexibility and elasticity to the shaft 3. Using metal as the constituent material of the shaft 3 can improve the pushability of the balloon catheter 1. Examples of resins that constitute 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 constituting 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. Examples of metals that constitute the shaft 3 include stainless steel such as SUS304 and SUS316, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, Ni-Ti alloy, Co-Cr alloy, or combinations thereof.

[0071] The shaft 3 may be a single shaft extending from the distal to the proximal end, or the shaft 3 may have a distal shaft and a proximal shaft made of separate members, with the proximal end of the distal shaft connected to the distal end of the proximal shaft to form the shaft 3. The distal shaft and the proximal shaft may be further composed of multiple tube members. If the shaft 3 is composed of a distal shaft and a proximal shaft, for example, both the distal shaft and the proximal shaft may be made of resin, or the distal shaft may be made of resin and the proximal shaft may be made of metal. The shaft 3 may also have a laminated structure made of different materials or the same material.

[0072] 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.

[0073] Although not shown in the figures, it is preferable that a tip member is provided at the distal end of the balloon catheter 1. The tip member may be provided at the distal end of the balloon catheter 1 by being connected to the distal end of the balloon 2 as a separate component from the inner tube 32 or inner shaft, or the inner tube 32 or inner shaft extending distal to the distal end of the balloon 2 may function as the tip member.

[0074] On the inner tube 32 or inner shaft inside the balloon 2, radiopaque markers may be placed at the location of the balloon 2 in the longitudinal axis direction x, so that the position of the balloon 2 can be confirmed under X-ray fluoroscopy. Preferably, the radiopaque markers are placed at positions corresponding to both ends of the straight tube portion 23 of the balloon 2, or at a position corresponding to the center of the straight tube portion 23 in the longitudinal axis direction x.

[0075] As shown in Figure 1, in the balloon catheter 1, a hub 4 may be provided on the proximal side of the shaft 3, and the hub 4 may be provided with a fluid injection section 7 that communicates with the fluid flow path 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 the so-called over-the-wire type balloon catheter 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 the balloon 2 according to the embodiment of the present invention can be applied to the so-called rapid exchange type balloon catheter in which the guidewire is inserted partway from the distal side to the proximal side of the shaft. In the case of the rapid exchange type, since the guidewire insertion section is provided partway from the distal side to the proximal side of the shaft, the hub 4 does not need to have a bifurcated structure.

[0076] 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.

[0077] This application claims the benefit of priority based on Japanese Patent Application No. 2021-182506, filed on November 9, 2021. The entire specification of Japanese Patent Application No. 2021-182506, filed on November 9, 2021, is incorporated herein by reference. [Explanation of symbols]

[0078] 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 63: Bottom 65: Transition Area 70: Hydrophilic coating layer 71: Highest edge of the hydrophilic coating layer x: Longitudinal axis y: radial direction z: 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. In at least a portion of the extension direction of the straight pipe portion, a hydrophilic coating layer is formed on the outer surface of the straight pipe portion at the boundary between a portion of the protrusion-forming region and a portion of the non-protrusion-forming region, and a hydrophilic coating layer is not formed in at least a portion of the protrusion-forming region that is not the boundary. In the region where no protrusion is 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 ends in the width direction than at the center in the width direction of the balloon catheter.

2. The balloon catheter according to claim 1, 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.

3. The straight pipe section has, in the direction of extension, a distal section, a central section, and a proximal section in that order. In the central section, a hydrophilic coating layer is formed at the boundary between the protruding portion forming region and the non-protruding portion forming region, extending from the protruding portion forming region to the non-protruding portion forming region. The balloon catheter according to claim 1 or 2, wherein in the distal and proximal sections, the boundary between the protruding portion forming region and the non-protruding portion forming region has a region from the protruding portion forming region to the non-protruding portion forming region in which the hydrophilic coating layer is not formed.

4. At least one of the distal tapered portion and the proximal tapered portion has a projection that protrudes radially outward from the balloon body and extends in the longitudinal direction of the balloon body. The balloon catheter according to claim 1 or 2, wherein there is a transition region in which the height decreases from the protruding portion of the straight tube to the protruding portion of the distal and / or proximal tapered portion, and a hydrophilic coating layer continuous with the hydrophilic coating layer of the straight tube is formed in at least a portion of the transition region.

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 claim 1 or 2, wherein at least one of the distal projection and the proximal projection is formed with a strip-shaped hydrophilic coating layer whose longitudinal direction is the direction of extension of the balloon body.

6. The balloon catheter according to claim 5, wherein a band-shaped hydrophilic coating layer is formed on both the distal projection and the proximal projection, the longitudinal direction of which is the direction of extension of the balloon body.

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. A transitional region exists where the height decreases from the protruding portion of the straight pipe section to the protruding portion of the distal and / or proximal tapered section equipped with the strip-shaped hydrophilic coating layer. The balloon catheter according to claim 5, wherein a hydrophilic coating layer continuous with the strip-shaped hydrophilic coating layer is formed in at least a portion of the transition region.

10. The balloon catheter according to claim 1 or 2, wherein the surface roughness A (Ra) of the area where the protrusion is not formed and the surface roughness B (Ra) of the area where the protrusion is formed satisfy the following formula (1). Surface roughness A (Ra) > Surface roughness B (Ra) - 5 μm ... (1)

11. The balloon catheter according to claim 1 or 2, wherein, when the balloon body is in a deflated state, the wing-forming portion formed by the non-protruding region of the straight tube portion covers the protruding portion.

12. The balloon catheter according to claim 1 or 2, wherein in the straight tube portion, a recess is formed in the protruding portion, and the highest end of the hydrophilic coating layer formed in the protruding portion is at the same height as the lowest part of the recess or higher than the lowest part of the recess.

13. The balloon catheter according to claim 1 or 2, wherein in the straight tube portion, a recess is formed in the protruding portion, and the highest end of the hydrophilic coating layer formed in the protruding portion is located lower than the lowest end of the recess.

14. The balloon catheter according to claim 10, wherein a recess is formed in the protruding portion of the straight tube portion, and the surface roughness C(Ra) of the bottom of the recess is greater than the surface roughness D(Ra) of the top of the protruding portion.

15. The balloon catheter according to claim 1 or 2, wherein at least a portion of the protruding portion forming region where a hydrophilic coating layer is not formed is having a hydrophobic coating layer.

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