Balloon catheter

Abstract

To provide a balloon catheter that is less prone to balloon displacement and can accurately apply pressure to the target area. [Solution] A balloon catheter 1 has a balloon group 11 including a plurality of balloons 10 arranged in parallel with each other in the circumferential direction z, wherein the balloon group 11 has a central region 121 including a midpoint P3 in the longitudinal direction x, a distal region 122 located distal to the central region 121, and a proximal region 123 located proximal to the central region 121, and at least one balloon 10 constituting the balloon group 11 has a protruding portion 200 projecting radially outward in the y direction from the central region 121.

Description

Technical Field

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

Background Art

[0002] When a stenosis formed by hardening such as calcification 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 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] There is a disease called aortic valve stenosis in which the aortic valve hardens due to calcification or the like, and the aortic valve becomes difficult to open, preventing blood flow. As a treatment for aortic valve stenosis, a method of surgically opening the chest and placing a biological valve (artificial valve) by catheter to replace the hardened aortic valve may be used.

[0004] The implanted biological valve deteriorates over time due to calcification, wear, etc. When the implanted biological valve deteriorates, it is necessary to replace the biological valve. In replacing the biological valve, a technique is being studied in which a plurality of balloon catheters are used to apply high pressure to the implanted biological valve to deform or destroy it, expand the lumen of the valve, and then implant a new biological valve inside the deformed or destroyed biological valve by transcatheter aortic valve replacement or the like.

[0005] As balloon catheters used for dilating hardened stenoses or implanting bioprosthetic valves, for example, Patent Document 1 discloses a catheter having an inflation means consisting of a plurality of inflation elements, characterized in that the walls of the plurality of inflation elements come together to form a substantially circular cross-section when the inflation means is inflated; Patent Document 2 discloses a balloon catheter having a plurality of balloon members, wherein a plurality of outer balloon members are arranged to surround the outer surface of an inner balloon member; Patent Document 3 discloses a balloon catheter having a plurality of balloons, which expand independently without being affected by other balloons, and which are separated from other balloons in the expanded state and do not come into contact with each other; Patent Document 4 discloses a device having a perfusion balloon having an internal passage and a balloon arranged in the internal passage of the perfusion balloon; and Patent Document 5 discloses a catheter including first to third balloons that can be inflated and deflated independently of each other. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 03-013907 [Patent Document 2] U.S. Patent Application Publication No. 2012 / 0209375 Specification [Patent Document 3] Japanese Patent Publication No. 2018-175550 [Patent Document 4] Special Publication No. 2018-536474 [Patent Document 5] International Publication No. 2021 / 054189 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, with the conventional balloon catheters described above, when multiple balloons are inflated to dilate a stenotic area or deform or destroy an implanted bioprosthetic valve, the balloons may move within the bioprosthetic lumen, causing displacement. This makes it difficult and time-consuming to adequately dilate the stenotic area or deform or destroy the bioprosthetic valve.

[0008] In view of the above circumstances, the present invention aims to provide a balloon catheter that is less prone to balloon displacement and can accurately apply pressure to the target location. [Means for solving the problem]

[0009] A balloon catheter according to an embodiment of the present invention that can solve the above problems is as follows. [1] A balloon catheter having a group of balloons including a plurality of balloons arranged in parallel to each other in the circumferential direction, The balloon group has a central region including the midpoint in the longitudinal direction, a distal region located distal to the central region, and a proximal region located proximal to the central region. A balloon catheter in which at least one of the balloons constituting the balloon group has a protruding portion in the central region that protrudes radially outward from the balloon. [2] The projection includes a distal projection and a distal projection located more proximal to the distal projection, The balloon catheter according to [1], wherein the midpoint is located between the distal projection and the proximal projection in the longitudinal direction. [3] The balloon catheter according to [1] or [2], wherein the protrusion is located outside the balloon group and is composed of a member that extends in at least a portion of the circumferential direction. [4] At least one of the balloons constituting the balloon group has a projection that protrudes along at least a portion of the circumferential direction, The balloon catheter according to any one of [1] to [3], wherein the protruding portion is composed of the projection. [5] The balloon catheter according to any one of [1] to [4], wherein the balloon group comprises an inner balloon and a plurality of outer balloons arranged radially outward from the inner balloon and in parallel with each other. [6] The inner balloons are multiple, The balloon catheter described in [5], wherein the multiple inner balloons are arranged in series with respect to each other. [7] The balloon catheter according to [5] or [6], wherein the length from the distal end of the inner balloon to the proximal end of the inner balloon in the expanded state of the inner balloon is shorter than the length from the distal end of the outer balloon to the proximal end of the outer balloon in the expanded state of the outer balloon. [Effects of the Invention]

[0010] According to the balloon catheter described above, at least one balloon constituting the balloon group has a protruding portion in its central region that extends radially outward from the balloon. This allows the protruding portion to hook onto the stenosis or bioprosthetic valve when multiple balloons constituting the balloon group are inflated, thereby holding the stenosis or bioprosthetic valve in place and making it less likely for the balloons to shift position. [Brief explanation of the drawing]

[0011] [Figure 1] This diagram shows an overall view of a balloon catheter according to one embodiment of the present invention. [Figure 2] Figure 1 shows a magnified view of the balloon portion of the balloon catheter. [Figure 3] This shows a cross-sectional view (III-III) of the balloon catheter shown in Figure 1. [Figure 4] Figure 1 shows a cross-sectional view of the balloon catheter from point IV to point IV. [Figure 5] This shows an enlarged view of the portion of a balloon catheter in another embodiment of the present invention where the balloon is located.

Best Mode for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described based on embodiments. However, the present invention is not limited to the following embodiments, and it is of course possible to appropriately modify and implement it within a range that conforms 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 the sake of convenience, hatching, member numbers, etc. may be omitted, but in such a case, 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.

[0013] A balloon catheter according to an embodiment of the present invention is a balloon catheter having a balloon group including a plurality of balloons arranged in parallel with each other in the circumferential direction. The balloon group has a central region including a midpoint in the longitudinal direction, a distal region located on the distal side of the central region, and a proximal region located on the proximal side of the central region. At least one balloon constituting the balloon group has a protruding portion protruding radially outward of the balloon in the central region.

[0014] Hereinafter, the balloon catheter according to the embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is an overall view of a balloon catheter according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a portion where the balloons of the balloon catheter shown in FIG. 1 are arranged. FIG. 3 is a cross-sectional view taken along line III-III of the balloon catheter shown in FIG. 1, representing a cross-sectional view perpendicular to the longitudinal direction at a portion where the balloons exist in a state where the balloons are expanded. FIG. 4 is a cross-sectional view taken along line IV-IV of the balloon catheter shown in FIG. 1, representing a cross-sectional view perpendicular to the longitudinal direction at a portion where the balloons exist in a state where the balloons are expanded. FIG. 5 is an enlarged view of a portion where the balloons of a balloon catheter according to another embodiment of the present invention are arranged.

[0015] As shown in FIGS. 1 to 5, the balloon catheter 1 has a balloon group 11 including a plurality of balloons 10 arranged in parallel with each other in the circumferential direction z. The balloon group 11 may have an inner balloon 40 and a plurality of outer balloons 50 arranged in parallel with each other outside the inner balloon 40 in the radial direction y. That is, the balloon catheter 1 may have an inner balloon 40 and an outer balloon 50. Hereinafter, when explaining the configuration common to the inner balloon 40 and the outer balloon 50, these or each of them may be simply referred to as a balloon 10. In addition, the plurality of balloons 10 including the inner balloon 40 and the plurality of outer balloons 50 included in the balloon catheter 1 may be referred to as a balloon group 11.

[0016] The balloon 10 has a longitudinal direction x, a radial direction y connecting the centroid of the outer edge of the balloon 10 and a point on the outer edge in a cross section perpendicular to the longitudinal direction x, and a circumferential direction z along the outer edge of the balloon 10 in a cross section perpendicular to the longitudinal direction x. In this specification, the direction on the user's hand side in the longitudinal direction x is referred to as the proximal side, and the direction opposite to the proximal side, that is, the direction on the side of the treatment target person is referred to as the distal side. Further, when each member or each part is bisected in the longitudinal direction x of the balloon 10, the part located on the distal side of each member or each part is referred to as the distal part of each member or each part, and the part located on the proximal side of each member or each part is referred to as the proximal part of each member or each part. The distal end of each member or each part is the end located on the most distal side of each member or each part. The proximal end of each member or each part is the end located on the most proximal side of each member or each part. The end portion includes the peripheral portion of the end. That is, the distal end portion refers to the distal end and the peripheral portion of the distal end, and the proximal end portion refers to the proximal end and the peripheral portion of the proximal end.

[0017] Other components and parts besides the balloon 10 also have longitudinal, radial, and circumferential directions, which may or may not be the same as the longitudinal x, radial y, and circumferential z directions of the balloon 10. However, for the sake of clarity, in this specification, all components and parts are described as having the same longitudinal x, radial y, and circumferential directions as the balloon 10.

[0018] The balloon 10 is located distal to the balloon catheter 1. The balloon 10 can be expanded by introducing fluid into its lumen, and the balloon 10 can be deflated by expelling fluid from its lumen. To control the expansion and contraction of the balloon 10, an indeflerator (balloon pressurizer) can be used to introduce or expel fluid. The fluid can be, for example, physiological saline or a mixture of contrast agent and physiological saline. The fluid may also be a pressurized fluid pressurized by a pump or the like.

[0019] Examples of materials that make up the balloon 10 include polyamide resins such as nylon 11 and nylon 12, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyurethane resins, and thermoplastic elastomers such as polyether block amide copolymers.

[0020] If the balloon group 11 has an inner balloon 40 and an outer balloon 50, the material constituting the inner balloon 40 may be the same as or different from the material constituting the outer balloon 50. If the balloon group 11 has multiple inner balloons 40, the materials constituting each of the multiple inner balloons 40 in the balloon catheter 1 may be different, but it is preferable that they be the same. In other words, it is preferable that the balloon group 11 includes multiple inner balloons 40 made of the same material. By having the same material constituting each of the multiple inner balloons 40, it becomes easier to make the degree of expansion, hardness, etc., of each of the multiple inner balloons 40 the same in the circumferential direction z.

[0021] Furthermore, if the balloon group 11 has multiple outer balloons 50, the materials constituting each of the multiple outer balloons 50 of the balloon catheter 1 may be different, but it is preferable that they be the same. In other words, it is preferable that the balloon group 11 includes multiple outer balloons 50 made of the same material. By having the same material constituting each of the multiple outer balloons 50, the degree of expansion and hardness of each of the multiple outer balloons 50 can be made to be of the same degree in the circumferential direction z.

[0022] As shown in Figure 2, it is preferable that the balloons 10 constituting the balloon group 11 have a straight tube portion 111, a distal tapered portion 112 located distal to the straight tube portion 111, and a proximal tapered portion 113 located proximal to the straight tube portion 111. It is also preferable that, because the balloon 10 has a straight tube portion 111, a distal tapered portion 112, and a proximal tapered portion 113, the balloon group 11 also 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.

[0023] The straight section 111 is preferably substantially cylindrical in shape, having approximately the same diameter in the longitudinal direction x, but may have different diameters in the longitudinal direction x. The distal tapered section 112 and the proximal tapered section 113 are preferably formed in a substantially conical or frustoconical shape, decreasing in diameter as they move away from the straight section 111. The straight section 111 has the maximum diameter, so that when the balloon group 11 is expanded in a lesion such as a stenosis, the straight section of the balloons 10 constituting the balloon group 11 can sufficiently contact the lesion, making it easier to perform treatment such as dilation of the lesion. Furthermore, because the distal tapered section 112 and the proximal tapered section 113 are reduced in diameter, when the balloon group 11 is deflated, the outer diameters of the proximal and distal ends of the balloons 10 constituting the balloon group 11 can be reduced, making it easier to insert the balloon catheter 1 into the body cavity.

[0024] Preferably, the balloon 10 constituting the balloon group 11 further includes a distal sleeve portion 114 located distal to the distal tapered portion 112, and a proximal sleeve portion 115 located proximal to the proximal tapered portion 113. In the balloon 10, while the straight tube portion 111, distal tapered portion 112, and proximal tapered portion 113 are parts that expand when fluid is introduced into the balloon 10, it is preferable that the distal sleeve portion 114 and proximal sleeve portion 115 do not expand. By preventing the distal sleeve portion 114 and proximal sleeve portion 115 from expanding, it is possible to easily fix at least a part of the distal sleeve portion 114 and at least a part of the proximal sleeve portion 115 to another object such as the shaft 70 of the balloon catheter 1. Details of the shaft 70 will be described later.

[0025] As shown in Figures 2 and 5, the balloon group 11 has a central region 121 that includes the midpoint P3 in the longitudinal direction x, a distal region 122 located distal to the central region 121, and a proximal region 123 located proximal to the central region 121. In other words, the portion of the balloon group 11 that includes the midpoint P3 in the longitudinal direction x is the central region 121.

[0026] The central region 121 is the region that includes the midpoint P3 in the longitudinal direction x of the balloon group 11. Preferably, the central region 121 is the region that includes the midpoint in the longitudinal direction x of the straight pipe section 111 of the balloon 10 included in the balloon group 11. Preferably, the central region 121 is a region with a length of 20% or more of the length of the straight pipe section 111 in the longitudinal direction x, more preferably a region with a length of 25% or more of the length of the straight pipe section 111, and even more preferably a region with a length of 30% or more of the length of the straight pipe section 111. By setting the lower limit of the length of the central region 121 in the longitudinal direction x to the above range, it becomes easier to determine the appropriate size of the central region 121.

[0027] The distal region 122 is a region located distal to the central region 121. In the longitudinal direction x, there may be further regions between the central region 121 and the distal region 122 that are different from the central region 121 and the distal region 122, but it is preferable that the central region 121 and the distal region 122 are adjacent. Furthermore, there may be further regions distal to the distal region 122 that are different from the distal region 122, but it is preferable that the distal region 122 is a region that includes the distal end 111d of the straight pipe section 111.

[0028] The distal region 122 is preferably a region having a length of 20% or more of the length of the straight pipe section 111 in the longitudinal direction x, more preferably a region having a length of 25% or more of the length of the straight pipe section 111, and even more preferably a region having a length of 30% or more of the length of the straight pipe section 111. By setting the lower limit of the length of the distal region 122 in the longitudinal direction x to the above range, it becomes easier to determine an appropriate size for the distal region 122.

[0029] The proximal region 123 is a region located proximal to the central region 121. In the longitudinal direction x, there may be further regions between the central region 121 and the proximal region 123 that are different from the central region 121 and the proximal region 123, but it is preferable that the central region 121 and the proximal region 123 are adjacent. Furthermore, there may be further regions proximal to the proximal region 123 that are different from the proximal region 123, but it is preferable that the proximal region 123 is a region that includes the proximal end 111p of the straight pipe section 111.

[0030] The proximal region 123 is preferably a region having a length of 20% or more of the length of the straight pipe section 111 in the longitudinal direction x, more preferably a region having a length of 25% or more of the length of the straight pipe section 111, and even more preferably a region having a length of 30% or more of the length of the straight pipe section 111. By setting the lower limit of the length of the proximal region 123 in the longitudinal direction x to the above range, it becomes easier to determine the appropriate size of the proximal region 123.

[0031] As shown in Figures 1 to 5, at least one balloon 10 constituting the balloon group 11 has a projection 200 in its central region 121 that protrudes radially outward in the y direction of the balloon 10. The projection 200 only needs to be located in the central region 121 of the balloon 10, and may or may not be located in the distal region 122 and the proximal region 123 of the balloon 10.

[0032] The protrusion 200 extends outward in the radial direction y of the balloon 10. The protrusion 200 may be present on all balloons 10 constituting the balloon group 11, or it may be present on only some of the balloons 10 constituting the balloon group 11.

[0033] Since at least one balloon 10 constituting the balloon group 11 has a protrusion 200 in the central region 121, the protrusion 200 can be hooked onto a stenosis or bioprosthetic valve when the multiple balloons 10 constituting the balloon group 11 are in an expanded state. Therefore, the protrusion 200 can hold the stenosis or bioprosthetic valve, resulting in a balloon catheter 1 in which displacement of the balloon 10 is less likely to occur.

[0034] As the material constituting the protrusion 200, for example, the materials listed as those constituting the balloon 10 can be used. Preferably, the material constituting the protrusion 200 is the same as the material constituting the balloon 10. By using the same material as the balloon 10, it becomes easier to prevent the protrusion 200 from damaging the balloon 10.

[0035] As shown in Figures 2 and 5, the protrusion 200 includes a distal protrusion 201 and a proximal protrusion 202 located proximal to the distal protrusion 201, and it is preferable that a midpoint P3 is located between the distal protrusion 201 and the proximal protrusion 202 in the longitudinal direction x. In other words, it is preferable that the distal protrusion 201 is located distal to the midpoint P3, and the proximal protrusion 202 is located proximal to the midpoint P3. Because the midpoint P3 is located between the distal protrusion 201 and the proximal protrusion 202 in the longitudinal direction x, the distal protrusion 201 and the proximal protrusion 202 can hold and secure the stenosis or bioprosthetic valve, etc., in the central part of the balloon group 11. Therefore, displacement of the balloon 10 is less likely to occur, and the expansion force of the balloon group 11 can be further increased.

[0036] As shown in Figure 3, it is preferable that the protrusion 200 is made of a member that is positioned outside the balloon group 11 and extends in at least a portion of the circumferential direction z. In other words, it is preferable that the protrusion 200 is made of a member separate from the balloons 10 that make up the balloon group 11, and that the protrusion 200 is made by positioning this separate member outside the balloon group 11. By making the protrusion 200 a member that is positioned outside the balloon group 11 and extends in at least a portion of the circumferential direction z, it becomes easier to provide the protrusion 200 at a desired position on the balloon group 11, making it easier to create a balloon catheter 1 that can prevent displacement of the balloons 10.

[0037] Furthermore, as shown in Figure 5, it is preferable that at least one balloon 10 constituting the balloon group 11 has a projection that protrudes along at least a portion of the circumferential direction z, and that the protruding portion 200 is composed of this projection. In other words, it is preferable that the protruding portion 200 is composed of a projection that is integral with the balloon 10 constituting the balloon group 11. By having the protruding portion 200 composed of a projection that is present on at least one balloon 10 constituting the balloon group 11, the protruding portion 200 is less likely to detach from the balloon 10, making it possible to create a highly safe balloon catheter 1.

[0038] As shown in Figures 1 to 5, the balloon group 11 preferably has an inner balloon 40 and a plurality of outer balloons 50 arranged in parallel to each other radially outward from the inner balloon 40. In other words, it is preferable that the plurality of outer balloons 50 are arranged along the outer circumference of the inner balloon 40.

[0039] The balloon group 11 comprises an inner balloon 40 and a plurality of outer balloons 50 arranged in parallel to each other radially outward from the inner balloon 40. As a result, the outer balloons 50 suppress the outward expansion of the inner balloon 40, and the inner balloon 40 suppresses the inward expansion of the outer balloons 50. Consequently, the inner balloon 40 and the outer balloons 50 mutually suppress each other's expansion, increasing the pressure resistance of the balloon group 11, thereby increasing the hardness of the balloons 10 constituting the balloon group 11 and improving its expansion force. Furthermore, the mutual suppression of each other's expansion by the inner balloon 40 and the outer balloons 50 makes it more difficult for the balloons 10 constituting the balloon group 11 to inflate. Therefore, even when high pressure is applied to each of the balloons 10 constituting the balloon group 11, over-expansion of the balloons 10 is suppressed, preventing the balloon group 11 from expanding beyond its intended outer diameter, thereby reducing damage to in vivo lumens such as the aortic valve and enhancing safety.

[0040] As shown in Figure 5, there may be multiple inner balloons 40, and these multiple inner balloons 40 may be arranged in series with each other. In other words, the multiple inner balloons 40 may be arranged in a row along the longitudinal direction x.

[0041] Because multiple inner balloons 40 are arranged in series with each other, when the inner balloons 40 and outer balloon 50 are expanded, the parts between the multiple inner balloons 40 do not expand, or expand less than other parts of the inner balloons 40. Therefore, the balloon group 11 located between the multiple inner balloons 40 does not expand as much as the outer balloon 50, and can be made concave. Since a stenosis or bioprosthetic valve can be held in place by being sandwiched in the concave part of the balloon group 11, a balloon catheter 1 can be made that is less prone to displacement of the balloon group 11.

[0042] In the expanded state, the maximum outer diameters of each of the multiple outer balloons 50 may be different, but it is preferable that they be the same. In other words, when the balloon group 11 is expanded, it is preferable that the maximum outer diameters of each of the multiple outer balloons 50 included in the balloon group 11 are the same. Having the same maximum outer diameter for each of the multiple outer balloons 50 of the balloon catheter 1 means that the maximum outer diameters of each of the multiple outer balloons 50 are approximately the same, and specifically, it means that the maximum outer diameter of one outer balloon 50 is 90% to 110% of the maximum outer diameter of all the other outer balloons 50. When the balloon group 11 is expanded, having the same maximum outer diameter for each of the multiple outer balloons 50 of the balloon catheter 1 makes it easier to synchronize the timing of expansion for all the outer balloons 50, and makes it easier to control the expansion of the balloon group 11. Note that when the balloon group 11 is expanded, it means that all the balloons 10 constituting the balloon group 11 are expanded.

[0043] During expansion, the maximum outer diameter of the inner balloon 40 may be the same as or different from the maximum outer diameter of the outer balloon 50. When the maximum outer diameter of the inner balloon 40 is the same as the maximum outer diameter of the outer balloon 50, it means that the maximum outer diameters of the inner balloon 40 and the outer balloon 50 are approximately the same. Specifically, it means that the maximum outer diameter of the inner balloon 40 is between 90% and 110% of the average value of the maximum outer diameter of the outer balloon 50. When the balloon group 11 is expanded, having the maximum outer diameter of the inner balloon 40 the same as the maximum outer diameter of the outer balloon 50 makes it easier to balance the force that the inner balloon 40 exerts to expand with the force that the outer balloon 50 exerts to suppress the expansion of the inner balloon 40. As a result, the hardness of the balloon group 11 increases, making it easier to increase the expansion force of the balloon group 11.

[0044] During expansion, the maximum outer diameter of the inner balloon 40 may be larger than the maximum outer diameter of the outer balloon 50. When the balloon group 11 is expanded, if the maximum outer diameter of the inner balloon 40 is larger than the maximum outer diameter of the outer balloon 50, the multiple outer balloons 50 are more likely to be evenly arranged along the outer circumference of the expanded inner balloon 40. As a result, when the balloon group 11 is deflated, the multiple outer balloons 50 are more likely to fold, making it possible to reduce the outer diameter of the balloon catheter 1 in the area where the balloon group 11 is located.

[0045] When the balloons are expanded, if the maximum outer diameter of the inner balloon 40 is greater than the maximum outer diameter of the outer balloon 50, the maximum outer diameter of the inner balloon 40 is preferably 1.10 times or more, more preferably 1.15 times or more, and even more preferably 1.20 times or more. By setting the lower limit of the ratio between the maximum outer diameter of the inner balloon 40 and the maximum outer diameter of the outer balloon 50 when the balloon group 11 is expanded to the above range, it becomes easier to evenly arrange multiple outer balloons 50 along the outer circumference of the inner balloon 40. Furthermore, when the balloon group 11 is expanded, the maximum outer diameter of the inner balloon 40 is preferably 3.0 times or less, more preferably 2.5 times or less, and even more preferably 2.0 times or less, of the maximum outer diameter of the outer balloon 50. By setting the upper limit of the ratio between the maximum outer diameter of the inner balloon 40 and the maximum outer diameter of the outer balloon 50 during the expansion of the balloon group 11 to the above range, it becomes easier to reduce the outer diameter of the portion of the balloon catheter 1 where the balloon group 11 is located when the balloon 10 is deflated, thereby making the balloon catheter 1 less invasive.

[0046] If the balloon group 11 has inner balloons 40, the number of inner balloons 40 may be one or more. If the balloon group 11 has multiple inner balloons 40, it is preferable that the number of inner balloons 40 be even. It is preferable that the number of inner balloons 40 be 6 or less, more preferably 4 or less, and even more preferably 2 or less. By setting the upper limit of the number of inner balloons 40 within the above range, the inner balloons 40 can more easily suppress the expansion of the outer balloon 50, making it possible to create a balloon catheter 1 with high expansion force. Note that the balloon catheter 1 may have multiple inner balloons 40, and the lower limit of the number of inner balloons 40 can be set to, for example, 2 or more.

[0047] When the balloon group 11 has an inner balloon 40 and an outer balloon 50, the number of outer balloons 50 is preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. By setting the lower limit of the number of outer balloons 50 within the above range, it becomes easier to surround the outer circumference of the inner balloon 40 with multiple outer balloons 50, and the outer balloons 50 can more easily suppress the expansion of the inner balloon 40. As a result, when fluid is introduced into the lumens of both the inner balloon 40 and the outer balloon 50 to expand the balloon group 11, the inner balloon 40 becomes less likely to inflate, the hardness of the inner balloon 40 increases, and the expansion force of the balloon group 11 can be increased. Furthermore, the number of outer balloons 50 in the balloon catheter 1 is preferably 20 or less, more preferably 12 or less, even more preferably 10 or less, and particularly preferably 8 or less. By setting the upper limit of the number of outer balloons 50 to the above range, when the balloon group 11 is expanded, the outer balloons 50 become less likely to move in the circumferential direction z, making it easier to suppress the expansion of the inner balloons 40 by the outer balloons 50.

[0048] As shown in Figure 5, it is preferable that the number of inner balloons 40 in the longitudinal direction x is greater than the number of outer balloons 50 in the longitudinal direction x. When the number of inner balloons 40 is greater than the number of outer balloons 50 in the longitudinal direction x, it becomes easier to evenly expand the outer diameter of the balloon group 11 in areas other than those with a concave shape during expansion of the balloon group 11. As a result, a balloon catheter 1 with a high expansion force of the balloon group 11 can be obtained.

[0049] It is preferable that the inner balloons 40 are not arranged in parallel. In other words, it is preferable that the balloon catheter 1 has multiple inner balloons 40 arranged in series, and not multiple inner balloons 40 arranged in parallel. To put it another way, it is preferable that there are multiple inner balloons 40 in the longitudinal direction x, and one inner balloon 40 in the radial direction y and the circumferential direction z. By having a configuration in which the inner balloons 40 are not arranged in parallel, the relative positional relationship of the multiple expanded inner balloons 40 is less likely to move in the radial direction y and the circumferential direction z when the balloon group 11 is expanded, and it is possible to expand the balloons 10 constituting the balloon group 11 evenly in the radial direction y and the circumferential direction z.

[0050] It is preferable that the outer balloons 50 are not arranged in series. In other words, it is preferable that the balloon catheter 1 has multiple outer balloons 50 arranged in parallel, and not multiple outer balloons 50 arranged in series. To put it another way, it is preferable that there are multiple outer balloons 50 in the radial direction y and the circumferential direction z, and one outer balloon 50 in the longitudinal direction x. By having a configuration in which the outer balloons 50 are not arranged in series, when the balloon group 11 is expanded, the outer balloons 50 expand more easily throughout the longitudinal direction x, and the expansion force of the balloon catheter 1 can be increased.

[0051] As shown in Figure 2, it is preferable that the length L40 from the distal end 40d to the proximal end 40p of the inner balloon 40 in its expanded state is shorter than the length L50 from the distal end 50d to the proximal end 50p of the outer balloon 50 in its expanded state. By making the length L40 of the inner balloon 40 shorter than the length L50 of the outer balloon 50, it becomes easier to increase the expansion force in the area where the inner balloon 40 is located. As a result, expansion can be performed efficiently while preventing displacement of the balloon group 11.

[0052] The length L40 from the distal end 40d to the proximal end 40p of the inner balloon 40 in its expanded state is preferably 50% or less, more preferably 45% or less, and even more preferably 40% or less, of the length L50 from the distal end 50d to the proximal end 50p of the outer balloon 50 in its expanded state. If the balloon group 11 has multiple inner balloons 40, the length L40 from the distal end 40d to the proximal end 40p of the inner balloon 40 refers to the length from the distal end 40d of the inner balloon 40 located furthest distal to the proximal end 40p of the inner balloon 40 located furthest proximal. By setting the upper limit of the ratio of the length L40 of the inner balloon 40 to the length L50 of the outer balloon 50 in its expanded state to the above range, it is possible to prevent the total length of the inner balloon 40 in the longitudinal direction x from becoming too long, resulting in a balloon catheter 1 that is easy to handle. Furthermore, the length L40 from the distal end 40d to the proximal end 40p of the inner balloon 40 in its expanded state is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more, of the length L50 from the distal end 50d to the proximal end 50p of the outer balloon 50 in its expanded state. By setting the lower limit of the ratio of the length L40 of the inner balloon 40 to the length L50 of the outer balloon 50 in its expanded state to the above range, it becomes easier to increase the overall expansion force of the balloon group 11.

[0053] When the balloon group 11 has multiple inner balloons 40, in the expanded state, the lengths from the distal end 40d to the proximal end 40p of each of the multiple inner balloons 40 in the longitudinal direction x of the balloon catheter 1 may be different, but are preferably the same. In other words, when the balloon group 11 is expanded, it is preferable that the lengths of each of the multiple inner balloons 40 included in the balloon group 11 are the same. Having the same lengths of each of the multiple inner balloons 40 in the balloon catheter 1 means that the lengths of each of the multiple inner balloons 40 are approximately the same, and specifically, it means that the length of one inner balloon 40 is 90% to 110% of the maximum length of all the other inner balloons 40. When the balloon group 11 is expanded, having the same lengths of each of the multiple inner balloons 40 in the balloon catheter 1 makes it easier to synchronize the expansion timing of all the inner balloons 40, and makes it easier to adjust the expansion of the balloon group 11.

[0054] In the expanded state, the length L50 from the distal end 50d to the proximal end 50p of each of the multiple outer balloons 50 of the balloon catheter 1 in the longitudinal direction x may be different, but it is preferable that they be the same. In other words, when the balloon group 11 is expanded, it is preferable that the length L50 of each of the multiple outer balloons 50 included in the balloon group 11 is the same. The fact that the length L50 from the distal end 50d to the proximal end 50p of each of the multiple outer balloons 50 of the balloon catheter 1 in the longitudinal direction x is the same means that the length L50 in the longitudinal direction x of each of the multiple outer balloons 50 included in the balloon group 11 is approximately the same, and specifically, it means that the length L50 in the longitudinal direction x of one outer balloon 50 is 90% to 110% of the length L50 in the longitudinal direction x of all the other outer balloons 50. During the expansion of the balloon group 11, the fact that the longitudinal x length L50 of the multiple outer balloons 50 of the balloon catheter 1 is the same makes it easier to synchronize the timing of the expansion of all the outer balloons 50, and thus makes it easier to control the expansion of the balloon group 11.

[0055] Although not shown in the figures, the multiple inner balloons 40 include a distal inner balloon 41 and a proximal inner balloon 42 adjacent to the distal inner balloon 41, and it is preferable that there is a gap between the distal inner balloon 41 and the proximal inner balloon 42 in the longitudinal direction x. In other words, the balloon catheter 1 has at least two inner balloons 40, a distal inner balloon 41 and a proximal inner balloon 42, and it is preferable that the proximal inner balloon 42 is positioned at a distance from the distal inner balloon 41 in the longitudinal direction x. By having a gap between the distal inner balloon 41 and the proximal inner balloon 42, the depth of the concave shape formed in the balloon group 11 can be increased, making it easier to grasp stenoses, bioprosthetic valves, etc. with the balloon group 11, and reducing the likelihood of displacement of the balloon group 11.

[0056] Preferably, the portion of the balloon group 11 where the gap between the distal inner balloon 41 and the proximal inner balloon 42 is located in the longitudinal direction x includes the midpoint P2 of the length L50 of the outer balloon 50 in the longitudinal direction x. In other words, it is preferable that the gap between the distal inner balloon 41 and the proximal inner balloon 42 is located at the position where the midpoint P2 of the length L50 of the outer balloon 50 in the longitudinal direction x is located. By including the midpoint P2 of the length L50 of the outer balloon 50 in the portion of the balloon group 11 where the gap between the distal inner balloon 41 and the proximal inner balloon 42 is located, the gap between the distal inner balloon 41 and the proximal inner balloon 42 can be positioned in the central part of the balloon group 11. As a result, when the balloon group 11 is expanded, a concave shape is formed in the central part of the balloon group 11, making it easier to apply load evenly from both sides of the stenosis or bioprosthetic valve by the balloon group 11 while grasping the stenosis or bioprosthetic valve in the central part of the balloon group 11.

[0057] It is more preferable that the midpoint of the gap between the distal inner balloon 41 and the proximal inner balloon 42 in the longitudinal direction x coincides with the midpoint P2 of the length L50 of the outer balloon 50 in the longitudinal direction x. By having the midpoint of the gap between the distal inner balloon 41 and the proximal inner balloon 42 coincide with the midpoint P2 of the length L50 of the outer balloon 50, a concave shape is formed in the center of the balloon group 11 when the balloon group 11 is expanded, making it possible to apply load more evenly from both sides of the stenotic portion or bioprosthetic valve that is gripped by the concave shape.

[0058] Although not shown in the diagram, the multiple inner balloons 40 include the most distal inner balloon 43, which is located at the most distal end, and the most proximal inner balloon 44, which is located at the most proximal end. Preferably, the distal end 43d of the most distal inner balloon 43 is located proximal to the distal end 50d of the outer balloon 50, and the proximal end 44p of the most proximal inner balloon 44 is located distal to the proximal end 50p of the outer balloon 50. Because the distal end 43d of the most distal inner balloon 43 is located proximal to the distal end 50d of the outer balloon 50, and the proximal end 44p of the most proximal inner balloon 44 is located distal to the proximal end 50p of the outer balloon 50, the sum of the lengths L40 of all the inner balloons 40 in the longitudinal direction x is smaller than the length L50 of the outer balloon 50 in the longitudinal direction x, and the sum of the lengths of all the inner balloons 40 in the longitudinal direction x is shorter than the length L50 of the outer balloon 50. As a result, the distal end of the most distal inner balloon 43 and the distal end of the outer balloon 50 are less likely to overlap, and the proximal end of the nearest inner balloon 44 and the proximal end of the outer balloon 50 are less likely to overlap, making it easier to reduce the outer diameter of the portion of the balloon catheter 1 where the balloon group 11 is located when the balloon group 11 is deflated.

[0059] The multiple inner balloons 40 may consist of a furthest distal inner balloon 43 and a nearest inner balloon 44, and may further include inner balloons 40 that are different from the furthest distal inner balloon 43 and the nearest inner balloon 44.

[0060] During expansion, the length from the distal end 43d of the most distal medial balloon 43 to the proximal end 44p of the nearest medial balloon 44 in the longitudinal direction x is preferably 95% or less, more preferably 90% or less, and even more preferably 85% or less of the length L50 from the distal end 50d of the outer balloon 50 to the proximal end 50p of the outer balloon 50 in the longitudinal direction x. By setting the upper limit of the ratio of the length from the distal end 43d of the most distal medial balloon 43 to the proximal end 44p of the nearest medial balloon 44 to the length L50 of the outer balloon 50 within the above range, a balloon catheter 1 can be made that can accurately apply high pressure to the target site. Furthermore, during expansion, the length from the distal end 43d of the most distal inner balloon 43 to the proximal end 44p of the nearest inner balloon 44 in the longitudinal direction x is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more of the length L50 from the distal end 50d of the outer balloon 50 to the proximal end 50p of the outer balloon 50 in the longitudinal direction x. By setting the lower limit of the ratio of the length from the distal end 43d of the most distal inner balloon 43 to the proximal end 44p of the nearest inner balloon 44 to the length L50 of the outer balloon 50 within the above range, it becomes easier to apply pressure to a sufficient area of ​​the target site with the balloon catheter 1, making it easier to expand the stenotic area or deform or destroy the bioprosthetic valve.

[0061] It is preferable that the distance from the distal end 43d of the most distal medial balloon 43 to the distal end 50d of the lateral balloon 50 in the longitudinal direction x is approximately the same as the distance from the proximal end 44p of the nearest medial balloon 44 to the proximal end 50p of the lateral balloon 50 in the longitudinal direction x. In other words, it is preferable that the distance from the distal end 43d of the most distal medial balloon 43 to the distal end 50d of the lateral balloon 50 in the longitudinal direction x is 90% to 110% of the distance from the proximal end 44p of the nearest medial balloon 44 to the proximal end 50p of the lateral balloon 50 in the longitudinal direction x. The distance from the distal end 43d of the most distal medial balloon 43 to the distal end 50d of the lateral balloon 50 is approximately the same as the distance from the proximal end 44p of the nearest medial balloon 44 to the proximal end 50p of the lateral balloon 50. As a result, the expansion of the lateral balloon 50 is more easily suppressed by the multiple medial balloons 40, thereby increasing the expansion force of the balloon group 11 and facilitating efficient expansion of stenotic areas and bioprosthetic valves.

[0062] In the expanded state, the maximum outer diameters of each of the multiple inner balloons 40 of the balloon catheter 1 may be different or the same. In other words, when the balloon group 11 is expanded, the maximum outer diameters of each of the multiple inner balloons 40 included in the balloon group 11 may be different or the same. The fact that the maximum outer diameters of each of the multiple inner balloons 40 of the balloon catheter 1 are the same means that the maximum outer diameters of each of the multiple inner balloons 40 are approximately the same, and specifically, it means that the maximum outer diameter of one inner balloon 40 is 90% to 110% of the maximum outer diameter of all the other inner balloons 40.

[0063] Although not shown in the diagram, the maximum outer diameter of the distal inner balloon 41 in its expanded state may be larger than the maximum outer diameter of the proximal inner balloon 42 in its expanded state. When the inner balloon 40 is expanded, the maximum outer diameter of the distal inner balloon 41 is larger than the maximum outer diameter of the proximal inner balloon 42, causing the distal portion of the inner balloon 40, which includes multiple inner balloons 40, to expand more than the proximal portion. As a result, the distal side of the balloon group 11 expands more easily than the proximal side, making it easier for the balloon group 11 to catch on stenoses or bioprosthetic valves, thus reducing the likelihood of displacement.

[0064] The maximum outer diameter of the distal inner balloon 41 in its expanded state is preferably 1.15 times or more, more preferably 1.20 times or more, and even more preferably 1.25 times or more, than the maximum outer diameter of the proximal inner balloon 42 in its expanded state. By setting the lower limit of the ratio between the maximum outer diameter of the distal inner balloon 41 and the maximum outer diameter of the proximal inner balloon 42 in their expanded states within the above range, the difference between the outer diameter of the distal and proximal parts of the entire group of inner balloons 40 becomes larger, making it easier for the balloon group 11 in its expanded state to catch on stenoses, bioprosthetic valves, etc. By setting the upper limit of the ratio between the maximum outer diameter of the distal inner balloon 41 and the maximum outer diameter of the proximal inner balloon 42 in the expanded state to the above range, the distal side of the balloon group 11 is less likely to become excessively large compared to the proximal side.

[0065] It is also preferable that the maximum outer diameter of the distal inner balloon 41 in its expanded state is larger than the overall outer diameter of the proximal inner balloon 42 in the longitudinal direction x in its expanded state. When the inner balloon 40 is expanded, the maximum outer diameter of the distal inner balloon 41 is larger than the overall outer diameter of the proximal inner balloon 42, which makes it easier for the distal portion of the balloon group 11 to expand more than the proximal portion. Therefore, when expanding a stenosis or bioprosthetic valve with the balloon group 11, the balloon group 11 is more likely to catch on the stenosis or bioprosthetic valve, allowing for efficient expansion while preventing displacement.

[0066] As shown in Figures 3 and 4, it is preferable that, in the expanded state of the outer balloon 50, the outer surfaces of at least one pair of adjacent outer balloons 50 are in contact with each other. When, in the expanded state of the outer balloon 50, at least one pair of adjacent outer balloons 50 are in contact with each other, when fluid is introduced into the balloon 10 and it is expanded, the adjacent outer balloons 50 suppress each other's expansion. As a result, the pressure of the fluid introduced into the lumen of the multiple outer balloons 50 increases, the hardness of the multiple outer balloons 50 increases, and the expansion force can be enhanced.

[0067] In the expanded state, it is preferable that all the outer balloons 50 of the balloon catheter 1 are in contact with each other. Specifically, in the case of a balloon catheter 1 with the configuration shown in Figure 3, it is preferable that the outer balloons 50 are in contact with the outer balloons 50 located on both sides of the outer balloon 50 in the circumferential direction z. When the outer balloons 50 are expanded, all the outer balloons 50 of the balloon catheter 1 are in contact with each other, so that when the balloon 10 expands, all the outer balloons 50 suppress each other's expansion, and the internal pressure of all the outer balloons 50 increases. As a result, the overall hardness of the balloon 10 increases, and the expansion force can be further enhanced.

[0068] As shown in Figures 3 and 4, when the inner balloon 40 and outer balloon 50 are inflated, it is preferable that the outer balloon 50 is in contact with the outer surface of the inner balloon 40. In other words, when the balloon 10 is inflated, it is preferable that at least one of the outer balloons 50 of the balloon catheter 1 is in contact with the outer surface of at least one inner balloon 40. When the outer balloon 50 is in contact with the outer surface of the inner balloon 40 in the expanded state, the inner balloon 40 and the outer balloon 50 tend to suppress each other's expansion when the balloon 10 is expanded. As a result, both the inner balloon 40 and the outer balloon 50 become less likely to inflate, making it easier to increase the expansion force of the balloon 10. Furthermore, by the inner balloon 40 and the outer balloon 50 suppressing each other's expansion, it is possible to prevent the inner balloon 40 and the outer balloon 50 from over-expanding when fluid is introduced into both the inner balloon 40 and the outer balloon 50 to create a high-pressure state.

[0069] In the expanded state of balloon 10, it is more preferable that all of the outer balloons 50 of the balloon catheter 1 are in contact with the outer surface of the inner balloon 40. When all of the outer balloons 50 of the balloon catheter 1 are in contact with the outer surface of the inner balloon 40 in the expanded state of balloon 10, the effect of the inner balloon 40 and the outer balloon 50 suppressing each other's expansion is enhanced, making it easier to further increase the expansion force of balloon 10.

[0070] As shown in Figures 1, 2, and 5, the balloon catheter 1 preferably further has a shaft 70 having a longitudinal direction x. The distal end of the shaft 70 is connected to the balloon 10, and it is preferable that the fluid that expands and deflates the balloon 10 is introduced and discharged through the lumen of the shaft 70.

[0071] The shaft 70 is preferably composed of resin, metal, or a combination of resin and metal. Using resin as a constituent material for the shaft 70 makes it easier to impart flexibility and elasticity to the shaft 70. Using metal as a constituent material for the shaft 70 can improve the delivery of the balloon catheter 1. Examples of resins that make up the shaft 70 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluororesins, vinyl chloride resins, silicone resins, natural rubber, and synthetic rubber. These may be used individually or in combination of two or more. Examples of metals that make up the shaft 70 include stainless steel such as SUS304 and SUS316, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, Ni-Ti alloy, Co-Cr alloy, or combinations thereof. The shaft 70 may also have a laminated structure made of different materials or the same material.

[0072] Figure 1 shows a so-called rapid exchange type balloon catheter 1, which has a guidewire port 191 located midway from the distal to the proximal end of the shaft 70, and a guidewire tube 192 that functions as a guidewire insertion passage from the guidewire port 191 to the distal end of the shaft 70. When the balloon catheter 1 is of the rapid exchange type, it is preferable that the balloon catheter 1 has a distal shaft 75 and a proximal shaft 76, and the distal shaft 75 and the proximal shaft 76 are separate components, and the shaft 70 extending from the balloon 10 to the proximal end of the balloon catheter 1 may be formed by connecting the proximal end of the distal shaft 75 to the distal end of the proximal shaft 76. When the shaft 70 is composed of a distal shaft 75 and a proximal shaft 76 which are separate components, for example, the distal shaft 75 may be formed from resin and the proximal shaft 76 may be formed from metal. Alternatively, one shaft 70 may extend from the balloon 10 to the proximal end of the balloon catheter 1, and the distal shaft 75 and the proximal shaft 76 may be composed of multiple tubular members.

[0073] Alternatively, although not shown in the figures, the present invention can also be applied to so-called over-the-wire type balloon catheters, which have a guidewire insertion passage extending from the distal to the proximal end of the shaft. When the balloon catheter is of the over-the-wire type, it is preferable that the inflation lumen and guidewire lumen extend to a hub located on the proximal end, and that the proximal opening of each lumen is provided in a bifurcated hub.

[0074] It is preferable that the shaft 70 has a fluid channel and a guide wire insertion passage inside. To configure the shaft 70 to have a fluid channel and a guide wire insertion passage inside, for example, a guide wire tube 192 located inside the shaft 70 can function as a guide wire insertion passage, and the space between the shaft 70 and the guide wire tube 192 can function as a fluid channel. In such a configuration, it is preferable that the guide wire tube 192 extends from the distal end of the shaft 70 and penetrates the balloon 10, with the distal side of the balloon 10 connected to the guide wire tube 192 and the proximal side of the balloon 10 connected to the shaft 70.

[0075] The shaft 70 has a first lumen which is a fluid passage, and the shaft 70 is positioned in the lumen of the proximal inner balloon 42 and connected to the distal inner balloon 41. Preferably, the first lumen communicates with the lumen of the distal inner balloon 41, and the lumen of the distal inner balloon 41 communicates with the lumen of the proximal inner balloon 42. Because the shaft 70 is positioned in the lumen of the proximal inner balloon 42 and connected to the distal inner balloon 41, with the first lumen communicating with the lumen of the distal inner balloon 41 and the lumen of the distal inner balloon 41 communicating with the lumen of the proximal inner balloon 42, the distal inner balloon 41 can be expanded before the proximal inner balloon 42. Therefore, the position of the balloon 10 in the biological lumen can be fixed by the distal inner balloon 41 while expanding the stenosis or biological valve, and displacement of the balloon 10 during expansion is less likely to occur.

[0076] The shaft 70 further has a second lumen, which is a fluid passage, and the second lumen may be in communication with the lumen of the outer balloon 50. By having the shaft 70 further have a second lumen that is in communication with the lumen of the outer balloon 50, it becomes possible to stagger the timing of the expansion and contraction of the inner balloon 40 and the outer balloon 50.

[0077] Although not shown in the diagram, in the expanded state of the most distal inner balloon 43, the maximum outer diameter of the distal part of the most distal inner balloon 43 may be larger than the maximum outer diameter of the proximal part of the most distal inner balloon 43. The distal part of the most distal inner balloon 43 is the part located on the distal side of the most distal inner balloon 43 when the most distal inner balloon 43 is divided into two equal parts along the longitudinal direction x, and the proximal part of the most distal inner balloon 43 is the part located on the proximal side of the most distal inner balloon 43 when the most distal inner balloon 43 is divided into two equal parts along the longitudinal direction x. In the expanded state of the most distal inner balloon 43, the maximum outer diameter of the distal part of the most distal inner balloon 43 is larger than the maximum outer diameter of the proximal part, which allows the outer diameter of the inner balloon 40 to be increased in the distal part of the balloon group 11. Therefore, the expansion force of the balloon group 11 can be increased distal to the concave shape of the central part of the balloon group 11.

[0078] In the expanded state of the most distal inner balloon 43, the maximum outer diameter of the distal part of the most distal inner balloon 43 is preferably 1.2 times or more, more preferably 1.3 times or more, and even more preferably 1.4 times or more, than the maximum outer diameter of the proximal part of the most distal inner balloon 43. By setting the lower limit of the ratio between the maximum outer diameter of the distal part and the maximum outer diameter of the proximal part of the most distal inner balloon 43 in the expanded state to the above range, the difference in outer diameter between the distal and proximal parts of the most distal inner balloon 43 can be increased, making it easier to increase the expansion force of the balloon group 11 distal to the concave shape of the balloon group 11. Furthermore, in the expanded state of the most distal inner balloon 43, the maximum outer diameter of the distal part of the most distal inner balloon 43 is preferably 5.0 times or less, more preferably 4.5 times or less, and even more preferably 4.0 times or less, than the maximum outer diameter of the proximal part of the most distal inner balloon 43. By setting the upper limit of the ratio between the maximum outer diameter of the distal part and the maximum outer diameter of the proximal part of the most distal inner balloon 43 in the expanded state to the above range, it is possible to prevent the outer diameter of the balloon group 11 distal to the concave shape of the balloon group 11 from becoming excessively large, thereby creating a balloon catheter 1 with high insertion rate.

[0079] The most distal inner balloon 43 may have a tapered shape, with its outer diameter increasing distally. In other words, the most distal inner balloon 43 may be a so-called tapered balloon. By having the most distal inner balloon 43 have a tapered shape, with its outer diameter increasing distally, a concave shape is easily formed in the portion of the most distal inner balloon 43 of the balloon group 11, and the expansion force of the balloon group 11 can be easily increased at both ends of this concave portion.

[0080] Although not shown in the diagram, in the expanded state of the nearest internal balloon 44, the maximum outer diameter of the proximal part of the nearest internal balloon 44 may be larger than the maximum outer diameter of the distal part of the nearest internal balloon 44. The proximal part of the nearest internal balloon 44 is the part located on the proximal side when the nearest internal balloon 44 is divided into two equal parts along the longitudinal direction x, and the distal part of the nearest internal balloon 44 is the part located on the distal side when the nearest internal balloon 44 is divided into two equal parts along the longitudinal direction x. In the expanded state of the nearest internal balloon 44, by having the maximum outer diameter of the proximal part of the nearest internal balloon 44 larger than the maximum outer diameter of the distal part, the outer diameter of the internal balloon 40 can be increased in the proximal part of the balloon group 11. Therefore, the expansion force of the balloon group 11 can be increased proximal to the concave shape of the central part of the balloon group 11.

[0081] In the expanded state of the nearest medial balloon 44, the maximum outer diameter of the proximal part of the nearest medial balloon 44 is preferably 1.2 times or more, more preferably 1.3 times or more, and even more preferably 1.4 times or more, than the maximum outer diameter of the distal part of the nearest medial balloon 44. By setting the lower limit of the ratio between the maximum outer diameter of the proximal part and the maximum outer diameter of the distal part of the nearest medial balloon 44 in the expanded state to the above range, the difference between the outer diameter of the proximal part and the outer diameter of the distal part of the nearest medial balloon 44 becomes larger, making it easier to increase the expansion force of the balloon group 11 on the proximal side of the concave shape of the balloon group 11. Furthermore, in the expanded state of the nearest medial balloon 44, the maximum outer diameter of the proximal part of the nearest medial balloon 44 is preferably 5.0 times or less, more preferably 4.5 times or less, and even more preferably 4.0 times or less, than the maximum outer diameter of the distal part of the nearest medial balloon 44. By setting the upper limit of the ratio between the maximum outer diameter of the proximal part and the maximum outer diameter of the distal part of the nearest medial balloon 44 in the expanded state to the above range, it is possible to prevent the outer diameter of the balloon group 11 from becoming excessively large proximal to the concave shape of the balloon group 11, thereby creating a balloon catheter 1 with high insertion rate.

[0082] The nearest internal balloon 44 may have a tapered shape, with its outer diameter increasing towards the proximal side. In other words, the nearest internal balloon 44 may be a so-called tapered balloon. The tapered shape of the nearest internal balloon 44, with its outer diameter increasing towards the proximal side, makes it easier to increase the depth of the concave shape of the balloon group 11, and allows the balloon group 11 to expand significantly at both ends of the concave portion, enabling efficient expansion.

[0083] The shaft 70 extends in the longitudinal direction x and has a guidewire lumen 93 through which a guidewire is inserted. It further has a guidewire tube 192 having a lumen that communicates with the guidewire lumen 93, and it is preferable that the guidewire tube 192 is positioned in the lumen of the inner balloon 40. The balloon catheter 1 having a guidewire tube 192 having a lumen that communicates with the guidewire lumen 93 makes it easy to insert the guidewire into the balloon catheter 1, and allows the balloon catheter 1 to be transported into the body along the guidewire. In addition, by inserting the guidewire into the guidewire tube 192, it is possible to prevent the guidewire from damaging the balloon 10, etc.

[0084] The materials constituting the guidewire tube 192 include, for example, polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon, polyester resins such as PET, aromatic polyetherketone resins such as PEEK, polyether polyamide resins, polyurethane resins, polyimide resins, fluororesins such as PTFE, PFA, and ETFE, and synthetic resins such as polyvinyl chloride resins. Among these, it is preferable that the material constituting the guidewire tube 192 be a polyimide resin. By using a polyimide resin as the material constituting the guidewire tube 192, the lubricity of the guidewire tube 192 is improved. Therefore, it becomes easier to insert the guidewire into the lumen of the guidewire tube 192 and to advance the balloon catheter 1 into the body along the guidewire. Furthermore, the guidewire tube 192 may have a multilayer structure with a braided layer such as a metal braid. By having a multilayer structure for the guidewire tube 192, the strength of the guidewire tube 192, its lubricity relative to the guidewire, and its kink resistance can be improved.

[0085] As shown in Figure 1, it is preferable that the proximal end of the guidewire tube 192 is connected to the distal end of the shaft 70. If the shaft 70 has a distal shaft 75 and a proximal shaft 76, it is preferable that the proximal end of the guidewire tube 192 is connected to the distal end of the distal shaft 75. By connecting the proximal end of the guidewire tube 192 to the distal end of the shaft 70, the outer diameter of the balloon catheter 1 is less likely to increase, thereby improving minimally invasiveness.

[0086] The balloon 10 and the shaft 70 can be joined by adhesive bonding, welding, or by attaching a ring-shaped member to the overlapping portion of the balloon 10 and the shaft 70 and crimping it. In particular, it is preferable that the balloon 10 and the shaft 70 are joined by welding. By joining the balloon 10 and the shaft 70 by welding, the joint between the balloon 10 and the shaft 70 is less likely to come undone even when the balloon 10 is repeatedly expanded or contracted, and the joint strength can be improved.

[0087] Preferably, a tip member 193 is provided at the distal end of the balloon catheter 1. The tip member 193 may be provided at the distal end of the balloon catheter 1 by being connected to the distal end of the balloon 10 as a separate component from the guide wire tube 192, or the guide wire tube 192 extending distal to the distal end of the balloon 10 may function as the tip member 193.

[0088] As shown in Figures 1, 2, and 5, an X-ray opaque marker 194 may be placed on the guidewire tube 192 inside the balloon 10 at the location of the balloon 10 in the longitudinal axis x direction, so that the position of the balloon 10 can be confirmed by X-ray fluoroscopy.

[0089] The positions on the guidewire tube 192 where the radiopaque marker 194 is placed include, for example, the midpoint of the length L40 from the distal end 40d of the inner balloon 40 to the proximal end 40p of the inner balloon 40, the positions of the proximal and distal ends of the straight section of the inner balloon 40, the midpoint of the length from the distal end 43d of the most distal inner balloon 43 to the proximal end 44p of the nearest inner balloon 44, the positions of the proximal end of the straight section of the most distal inner balloon 43 and the distal end of the straight section of the nearest inner balloon 44, and the positions of the proximal and distal ends of the straight section of the outer balloon 50. In particular, the positions on the guidewire tube 192 where the radiopaque marker 194 is placed are preferably the positions of the proximal end of the straight section of the most distal inner balloon 43 and the distal end of the straight section of the nearest inner balloon 44. The radiopaque marker 194 is positioned on the guidewire tube 192 located at the proximal end of the straight section of the most distal medial balloon 43 and the distal end of the straight section of the nearest medial balloon 44, making it easier to identify the portion of the balloon 10 that forms a concave shape. As a result, the balloon catheter 1 can be made more responsive to grasping stenoses, bioprosthetic valves, etc., in the concave portion, and less prone to displacement.

[0090] As shown in Figure 1, a hub 5 may be provided on the proximal side of the shaft 70. Furthermore, the hub 5 may be provided with a fluid injection section 6 that communicates with the fluid flow path supplied to the inside of the balloon 10.

[0091] The shaft 70 and the hub 5 can be joined by, for example, adhesive bonding or welding. In particular, it is preferable that the shaft 70 and the hub 5 are joined by adhesive bonding. By joining the shaft 70 and the hub 5 by adhesive bonding, the strength of the joint between the shaft 70 and the hub 5 can be increased, thereby improving the durability of the balloon catheter 1, especially when the materials constituting the shaft 70 and the hub 5 are different, for example, when the shaft 70 is made of a highly flexible material and the hub 5 is made of a highly rigid material.

[0092] If the balloon catheter 1 is a rapid exchange type, the outer wall of at least one of the distal shaft 75 and the proximal shaft 76 may be coated, or both the distal shaft 75 and the proximal shaft 76 may be coated. If the balloon catheter 1 is an over-the-wire type, the outer wall of the outer shaft may be coated.

[0093] The coating applied to the shaft 70 can be either a hydrophilic or hydrophobic coating, depending on the purpose. This coating can be applied by immersing the shaft 70 in a hydrophilic or hydrophobic coating agent, applying a hydrophilic or hydrophobic coating agent to the outer wall of the shaft 70, or covering the outer wall of the shaft 70 with a hydrophilic or hydrophobic coating agent. The coating agent may contain chemicals or additives.

[0094] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and methyl vinyl ether maleic anhydride copolymer, or hydrophilic coating agents made from any combination thereof.

[0095] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), ethylene fluoride propylene (FEP), perfluoroalkoxyalkanes (PFA), silicone oil, hydrophobic urethane resins, carbon coatings, diamond coatings, diamond-like carbon (DLC) coatings, ceramic coatings, and substances with low surface free energy terminated with alkyl groups or perfluoroalkyl groups.

[0096] The balloon catheter 1 of the present invention is preferably used to expand the aortic valve, deform a bioprosthetic valve implanted in the heart, or destroy a bioprosthetic valve. Specifically, the balloon catheter 1 of the present invention is preferably used to expand an aortic valve that has hardened due to calcification, etc., or to deform or destroy the prosthetic annulus of a bioprosthetic valve in order to replace a deteriorated bioprosthetic valve that has been implanted in the heart. Because the balloon catheter 1 of the present invention makes it easy to apply high pressure in the area where the inner balloon 40 is located, it is suitable for use in expanding hardened aortic valves and deforming or destroying bioprosthetic valves, which could not be sufficiently expanded with conventional balloon catheters. [Explanation of Symbols]

[0097] 1: Balloon catheter 5: Hub 6:Fluid injection part 10: Balloon 11: Balloon Group 40: Inner balloon 40d: Distal end of the medial balloon 40p: Proximal end of the inner balloon 41: Distal medial balloon 42: Proximal medial balloon 43: Most distal medial balloon 43d: Distal end of the most distal medial balloon 43p: Proximal end of the most distal medial balloon 44: Recent internal balloon 44d: Distal end of the medial balloon at the nearest position 44p: Proximal end of the medial balloon at the nearest position 50: Outer balloon 50d: Distal end of the outer balloon 50p: Proximal end of the outer balloon 70: Shaft 75: Distal shaft 76: Proximal shaft 93: Guide wire lumen 111: Straight pipe section 111d: Distal end of the straight pipe section 111p: Proximal end of the straight pipe section 112: Distal tapered section 113: Proximal tapered section 114: Distal sleeve portion 115: Proximal sleeve portion 121: Central area 122: Distal region 123: Proximal region 191: Guide wire port 192: Guide wire tube 193: Tip component 194: X-ray opaque marker 200:Protrusion 201: Distal projection 202: Proximal projection P2: Midpoint of the length of the outer balloon P3: Midpoint of the balloon group in the longitudinal direction L40: Length of the inner balloon L50: Length of the outer balloon

Claims

1. A balloon catheter having a group of balloons including a plurality of balloons arranged in parallel to each other in the circumferential direction, The balloon group has a central region including the midpoint in the longitudinal direction, a distal region located distal to the central region, and a proximal region located proximal to the central region. A balloon catheter in which at least one of the balloons constituting the balloon group has a protruding portion in the central region that protrudes radially outward from the balloon.

2. The aforementioned projection includes a distal projection and a proximal projection located more proximal to the distal projection. The balloon catheter according to claim 1, wherein the midpoint is located between the distal projection and the proximal projection in the longitudinal direction.

3. The balloon catheter according to claim 1 or 2, wherein the protruding portion is composed of a member that is located outside the balloon group and extends in at least a portion of the circumferential direction.

4. At least one of the balloons constituting the balloon group has a projection that protrudes along at least a portion of the circumferential direction, The balloon catheter according to claim 1 or 2, wherein the protruding portion is formed by the projection.

5. The balloon catheter according to claim 1 or 2, wherein the balloon group comprises an inner balloon and a plurality of outer balloons arranged radially outward from the inner balloon and in parallel with each other.

6. The aforementioned inner balloons are numerous, The balloon catheter according to claim 5, wherein the plurality of inner balloons are arranged in series with respect to each other.

7. The balloon catheter according to claim 5, wherein the length from the distal end to the proximal end of the inner balloon in the expanded state of the inner balloon is shorter than the length from the distal end to the proximal end of the outer balloon in the expanded state of the outer balloon.

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