Balloon catheter

Abstract

To provide a balloon catheter in which balloon displacement is unlikely to occur and pressure can be accurately applied to a target site.SOLUTION: A balloon catheter 1 comprises: a plurality of inner balloons 40 arranged in series with each other; and a plurality of outer balloons 50 arranged in parallel with each other and radially outward of the inner balloons 40.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] The formation of narrowed areas due to calcification and other factors in the inner walls of blood vessels can lead to diseases such as angina pectoris and myocardial infarction. One treatment for these conditions is angioplasty, which uses a balloon catheter to dilate the narrowed area. Angioplasty is a minimally invasive treatment that does not require open chest surgery like bypass surgery, and is widely used.

[0003] Aortic stenosis is a condition in which the aortic valve becomes hardened due to calcification, making it difficult to open and obstructing blood flow. Treatment for aortic stenosis involves open-chest surgery and catheter-based placement of a biological valve (artificial valve) to replace the hardened aortic valve.

[0004] An implanted bioprosthetic valve deteriorates over time due to calcification, wear, and other factors. When an implanted bioprosthetic valve deteriorates, it must be replaced. One procedure under consideration for replacing a bioprosthetic valve involves applying high pressure to the implanted bioprosthetic valve using multiple balloon catheters, deforming or destroying it, expanding the valve lumen, and then placing a new bioprosthetic valve inside the deformed or destroyed bioprosthetic valve using techniques such as transcatheter aortic valve replacement.

[0005] As examples of balloon catheters used for dilating hardened stenotic lesions or placing biological valves, Patent Document 1 discloses a catheter characterized by having an expansion means composed of multiple expansion elements, the walls of which together form a substantially circular cross section when the expansion means is inflated. Patent Document 2 discloses a balloon catheter having multiple balloon members, with multiple outer balloon members arranged to surround the outer surface of an inner balloon member. Patent Document 3 discloses a balloon catheter having multiple balloons that expand independently without being affected by the other balloons and that remain separate from the other balloons after expansion. Patent Document 4 discloses a device having a perfusion balloon with an internal passage and a balloon disposed in the internal passage of the perfusion balloon. Patent Document 5 discloses a catheter including first, second, and 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] US Patent Application Publication No. 2012 / 0209375 [Patent Document 3] Japanese Patent Application Publication No. 2018-175550 [Patent Document 4] Special Publication No. 2018-536474 [Patent Document 5] International Publication No. 2021 / 054189 Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the above-mentioned conventional balloon catheters, when multiple balloons are inflated to dilate the narrowed area or to deform or destroy the implanted biological valve, the balloons may move within the biological lumen, causing misalignment, making it difficult or time-consuming to dilate the narrowed area or to deform or destroy the implanted biological valve.

[0008] In view of the above circumstances, an object of the present invention is to provide a balloon catheter in which the balloon is less likely to shift position and which can accurately apply pressure to a 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 plurality of inner balloons arranged in series with each other; A balloon catheter having a plurality of outer balloons arranged in parallel to each other radially outward of the inner balloon. [2] The balloon catheter according to [1], wherein the number of inner balloons in the longitudinal direction is greater than the number of outer balloons in the longitudinal direction. [3] A balloon catheter according to [1] or [2], wherein the length from the distal end of the inner balloon to the proximal end of the inner balloon when the inner balloon is in an expanded state is shorter than the length from the distal end of the outer balloon to the proximal end of the outer balloon when the outer balloon is in an expanded state. [4] The plurality of inner balloons include a distal inner balloon and a proximal inner balloon adjacent to the distal inner balloon; The balloon catheter according to any one of [1] to [3], wherein a gap is provided between the distal inner balloon and the proximal inner balloon in the longitudinal direction. [5] A balloon catheter as described in [4], wherein the portion where the gap between the distal inner balloon and the proximal inner balloon is located in the longitudinal direction includes the midpoint of the length of the outer balloon in the longitudinal direction. [6] The plurality of inner balloons includes a distal-most inner balloon disposed most distally and a proximal-most inner balloon disposed most proximally; a distal end of the most distal inner balloon is located proximal to a distal end of the outer balloon; The balloon catheter according to any one of [1] to [5], wherein the proximal end of the most proximal inner balloon is located distal to the proximal end of the outer balloon. [7] The plurality of inner balloons include a distal inner balloon and a proximal inner balloon adjacent to the distal inner balloon; The balloon catheter according to any one of [1] to [6], wherein the maximum outer diameter of the distal inner balloon in an inflated state is larger than the maximum outer diameter of the proximal inner balloon in an inflated state. [8] The method further includes a shaft having a longitudinal direction; the plurality of inner balloons include a distal inner balloon and a proximal inner balloon adjacent to the distal inner balloon; The shaft has a first lumen that is a fluid flow path, the shaft is disposed within the lumen of the proximal inner balloon and is connected to the distal inner balloon; the first lumen communicates with the lumen of the distal inner balloon; The balloon catheter according to any one of [1] to [7], wherein the lumen of the distal inner balloon communicates with the lumen of the proximal inner balloon. [9] The plurality of inner balloons includes a distal-most inner balloon disposed most distally and a proximal-most inner balloon disposed most proximally; The balloon catheter according to any one of [1] to [8], wherein, in an inflated state of the distalmost inner balloon, the maximum outer diameter of the distal portion of the distalmost inner balloon is larger than the maximum outer diameter of the proximal portion of the distalmost inner balloon.

[10] The plurality of inner balloons includes a distal-most inner balloon disposed most distally and a proximal-most inner balloon disposed most proximally; The balloon catheter according to any one of [1] to [9], wherein, in an inflated state of the proximal-most inner balloon, the maximum outer diameter of the proximal portion of the proximal-most inner balloon is larger than the maximum outer diameter of the distal portion of the proximal-most inner balloon. [Effects of the Invention]

[0010] The balloon catheter has multiple inner balloons arranged in series and multiple outer balloons arranged in parallel radially outward of the inner balloons, so that when the inner and outer balloons are in an inflated state, the portions of the balloon between the multiple inner balloons have a concave shape, which can hold the stenosis or biological valve, etc., and makes it less likely for the balloon to shift position. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an overall view of a balloon catheter according to an embodiment of the present invention. [Figure 2] 2 is an enlarged view of a portion of the balloon catheter shown in FIG. 1 where a balloon is disposed. [Figure 3] 3 is a cross-sectional view of the balloon catheter shown in FIG. 1 taken along line III-III. [Figure 4] 4 shows a cross-sectional view of the balloon catheter shown in FIG. 1 taken along line IV-IV. [Figure 5] 10 is an enlarged view of a portion of a balloon catheter according to another embodiment of the present invention in which a balloon is disposed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described below based on the embodiments, but the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the above and below-described purposes, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component symbols may be omitted in each drawing for convenience. In such cases, reference should be made to the specification or other drawings. The dimensions of various components in the drawings may differ from actual dimensions, as priority is given to helping understand the features of the present invention.

[0013] A balloon catheter according to an embodiment of the present invention has a plurality of inner balloons arranged in series with each other and a plurality of outer balloons arranged in parallel with each other radially outward of the inner balloons.

[0014] Hereinafter, a balloon catheter according to an embodiment of the present invention will be described with reference to Figures 1 to 5. Figure 1 is an overall view of a balloon catheter according to an embodiment of the present invention, and Figure 2 is an enlarged view of a portion of the balloon catheter shown in Figure 1 where a balloon is disposed. Figure 3 is a cross-sectional view taken along line III-III of the balloon catheter shown in Figure 1, showing a cross-sectional view perpendicular to the longitudinal direction of the portion where the balloon is present when the balloon is in an expanded state. Figure 4 is a cross-sectional view taken along line IV-IV of the balloon catheter shown in Figure 1, showing a cross-sectional view perpendicular to the longitudinal direction of the portion where the balloon is present when the balloon is in an expanded state. Figure 5 is an enlarged view of a portion where a balloon is disposed of a balloon catheter according to another embodiment of the present invention.

[0015] 1 to 5, the balloon catheter 1 has an inner balloon 40 and an outer balloon 50. Hereinafter, when describing 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. Furthermore, the plurality of balloons 10, including the plurality of inner balloons 40 and the plurality of outer balloons 50 possessed by 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 to 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 toward the user in the longitudinal direction x is referred to as the proximal side, and the direction opposite the proximal side, i.e., toward the patient, is referred to as the distal side. Furthermore, when each component or part of the balloon 10 is divided into two equal parts in the longitudinal direction x, the distal part of each component or part is referred to as the distal part of each component or part, and the proximal part of each component or part is referred to as the proximal part of each component or part. The distal end of each component or part is the most distal end of each component or part. The proximal end of each component or part is the most proximal end of each component or part. The term "end" includes the peripheral portion of the end. That is, the distal end refers to the distal end and the area surrounding the distal end, and the proximal end refers to the proximal end and the area surrounding the proximal end.

[0017] Components and parts other than the balloon 10 also have longitudinal, radial, and circumferential directions, which may or may not be the same as the longitudinal direction x, radial direction y, and circumferential direction z of the balloon 10. However, for ease of understanding, this specification will be described assuming that all components and parts have the same longitudinal, radial, and circumferential directions as the longitudinal direction x, radial direction y, and circumferential direction z of the balloon 10.

[0018] The balloon 10 is located at the distal portion of the balloon catheter 1. The balloon 10 can be expanded by introducing a fluid into the lumen of the balloon 10, and can be deflated by discharging the fluid from the lumen of the balloon 10. To control the expansion and contraction of the balloon 10, a fluid can be introduced or discharged using an indeflator (a balloon pressurizer). The fluid can be, for example, saline or a mixture of a contrast agent and saline. The fluid may also be a pressurized fluid pressurized by a pump or the like.

[0019] Examples of materials that can be used to form 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] The material constituting the inner balloon 40 may be the same as or different from the material constituting the outer balloon 50. The materials constituting each of the multiple inner balloons 40 in the balloon catheter 1 may be different, but are preferably the same. In other words, the balloon group 11 preferably includes multiple inner balloons 40 made of the same material. Constituting each of the multiple inner balloons 40 with the same material makes it easier to make the degree of expansion, hardness, etc. of each of the multiple inner balloons 40 equal in the circumferential direction z.

[0021] Furthermore, although the materials constituting each of the multiple outer balloons 50 of the balloon catheter 1 may be different, they are preferably the same. In other words, the balloon group 11 preferably includes multiple outer balloons 50 made of the same material. By making each of the multiple outer balloons 50 out of the same material, the degree of expansion, hardness, etc. of each of the multiple outer balloons 50 can be made approximately the same in the circumferential direction z.

[0022] 1, 2, and 5, the balloon catheter 1 has multiple inner balloons 40, which are arranged in series with one another. In other words, the multiple inner balloons 40 are arranged side by side in a line in the longitudinal direction x.

[0023] 1 to 5, the balloon catheter 1 has multiple outer balloons 50, which are arranged in parallel with one another radially outward from the inner balloon 40. In other words, the multiple outer balloons 50 are arranged along the outer periphery of the inner balloon 40.

[0024] Because the balloon catheter 1 has multiple inner balloons 40 arranged in series with one another and multiple outer balloons 50 arranged in parallel with one another radially outward of the inner balloons 40, when the inner balloons 40 and the outer balloons 50 are inflated, the portions between the multiple inner balloons 40 do not inflate or inflate less than the other portions of the inner balloon 40. Therefore, the portions of the balloon group 11 located between the multiple inner balloons 40 are less likely to inflate the outer balloon 50, and can be made concave. Because a stenosis site, a biological valve, or the like can be sandwiched and held in this concave portion of the balloon group 11, the balloon catheter 1 is less likely to shift position of the balloon group 11.

[0025] Furthermore, because the balloon catheter 1 includes an inner balloon 40 and multiple outer balloons 50 arranged radially outward of the inner balloon 40, the multiple outer balloons 50 suppress outward expansion of the inner balloon 40, and the inner balloon 40 suppresses inward expansion of the multiple outer balloons 50. As a result, the inner balloon 40 and the multiple outer balloons 50 mutually suppress their respective expansions, making the balloon group 11 highly pressure-resistant, increasing the hardness of the multiple balloons 10 constituting the balloon group 11 and improving their expansion force. Furthermore, the inner balloon 40 and the multiple outer balloons 50 mutually suppress their respective expansions, making the multiple balloons 10 constituting the balloon group 11 less likely to expand. 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 balloons 11 from expanding beyond the intended outer diameter. This reduces damage to intravascular lumens such as the aortic valve and improves safety.

[0026] The balloon 10 preferably has a straight tube portion, a proximal tapered portion located proximal to the straight tube portion, and a distal tapered portion located distal to the straight tube portion. The straight tube portion is preferably substantially cylindrical with approximately the same diameter in the longitudinal direction x, but may have different diameters in the longitudinal direction x. The proximal tapered portion and the distal tapered portion preferably have a substantially conical or truncated conical shape with a diameter decreasing with increasing distance from the straight tube portion. The straight tube portion having the largest diameter ensures that, when the balloon group 11 is expanded at a lesion such as a stenosis, the straight tube portions of the balloons 10 constituting the balloon group 11 sufficiently contact the lesion, facilitating treatment such as dilation of the lesion. Furthermore, because the proximal tapered portion and the distal tapered portion are reduced in diameter, the outer diameters of the proximal and distal ends of the balloons 10 constituting the balloon group 11 can be reduced when the balloon group 11 is deflated, thereby facilitating insertion of the balloon catheter 1 into a body cavity.

[0027] Preferably, the balloon 10 further includes a proximal sleeve portion located proximal to the proximal tapered portion and a distal sleeve portion located distal to the distal tapered portion. In the balloon 10, the straight tube portion, proximal tapered portion, and distal tapered portion are portions that expand when a fluid is introduced into the balloon 10, whereas the proximal sleeve portion and distal sleeve portion preferably do not expand. By making the proximal sleeve portion and distal sleeve portion non-expandable, at least a portion of the proximal sleeve portion and at least a portion of the distal sleeve portion can be easily secured to other objects, such as the shaft 70 of the balloon catheter 1. Details of the shaft 70 will be described later.

[0028] In the expanded state, the maximum outer diameters of the multiple outer balloons 50 of the balloon catheter 1 may be different, but are preferably the same. That is, when the balloon group 11 is expanded, the maximum outer diameters of the multiple outer balloons 50 of the balloon group 11 are preferably the same. The multiple outer balloons 50 of the balloon catheter 1 having the same maximum outer diameter means that the maximum outer diameters of the multiple outer balloons 50 are approximately the same. Specifically, this means that the maximum outer diameter of one outer balloon 50 is 90% to 110% of the maximum outer diameters of all the other outer balloons 50. When the balloon group 11 is expanded, the multiple outer balloons 50 of the balloon catheter 1 have the same maximum outer diameter, which makes it easier to synchronize the expansion timing of all the outer balloons 50 and to control the expansion of the balloon group 11. Note that when the balloon group 11 is expanded, all of the balloons 10 constituting the balloon group 11, including the multiple inner balloons 40 and the multiple outer balloons 50, are expanded.

[0029] 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. The fact that the maximum outer diameter of the inner balloon 40 is the same as the maximum outer diameter of the outer balloon 50 means that the maximum outer diameter of the inner balloon 40 and the maximum outer diameter of the outer balloon 50 are approximately the same. Specifically, this means that the maximum outer diameter of the inner balloon 40 is 90% to 110% of the average maximum outer diameter of the outer balloon 50. During expansion of the balloon group 11, the fact that the maximum outer diameter of the inner balloon 40 is the same as the maximum outer diameter of the outer balloon 50 facilitates balancing between the force exerted by the inner balloon 40 to expand and the force exerted by the expansion of the outer balloon 50 to suppress the expansion of the inner balloon 40. As a result, the rigidity of the balloon group 11 is increased, making it easier to increase the expansion force of the balloon group 11.

[0030] When expanded, the maximum outer diameter of the inner balloon 40 is preferably larger than the maximum outer diameter of the outer balloon 50. When the balloon group 11 is expanded, the maximum outer diameter of the inner balloon 40 is larger than the maximum outer diameter of the outer balloon 50, which makes it easier to arrange the multiple outer balloons 50 evenly along the outer periphery of the expanded inner balloon 40. Therefore, when the balloon group 11 is deflated, the multiple outer balloons 50 are easily folded, making it possible to reduce the outer diameter of the portion of the balloon catheter 1 where the balloon group 11 is located.

[0031] When inflated, the maximum outer diameter of the inner balloon 40 is preferably at least 1.10 times, more preferably at least 1.15 times, and even more preferably at least 1.20 times, the maximum outer diameter of the outer balloon 50. By setting the lower limit of the ratio of the maximum outer diameter of the inner balloon 40 to the maximum outer diameter of the outer balloon 50 when the balloon group 11 is inflated within the above range, it becomes easier to evenly arrange the multiple outer balloons 50 around the circumference of the inner balloon 40. Furthermore, when the balloon group 11 is inflated, the maximum outer diameter of the inner balloon 40 is preferably no more than 3.0 times, more preferably no more than 2.5 times, and even more preferably no more than 2.0 times the maximum outer diameter of the outer balloon 50. By setting the upper limit of the ratio of the maximum outer diameter of the inner balloon 40 to the maximum outer diameter of the outer balloon 50 when the balloon group 11 is inflated within 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 in a deflated state, thereby making the balloon catheter 1 less invasive.

[0032] The number of inner balloons 40 in the balloon catheter 1 is preferably an even number. The number of inner balloons 40 is preferably six or less, more preferably four or less, and even more preferably two 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, resulting in a balloon catheter 1 with high expansibility. Note that the balloon catheter 1 may have any number of inner balloons 40 as long as it is plural, and the lower limit of the number of inner balloons 40 can be set, for example, to two or more.

[0033] The number of outer balloons 50 included in the balloon catheter 1 is preferably three or more, more preferably four or more, and even more preferably five or more. Setting the lower limit of the number of outer balloons 50 within the above range makes it easier for multiple outer balloons 50 to surround the outer periphery of the inner balloon 40, which makes it easier for the outer balloons 50 to suppress the expansion of the inner balloon 40. As a result, when fluid is introduced into the lumen of both the inner balloon 40 and the outer balloon 50 to expand the balloon group 11, the inner balloon 40 is less likely to expand, increasing the hardness of the inner balloon 40 and making it easier to increase the expansion force of the balloon group 11. Furthermore, the number of outer balloons 50 included 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. Setting the upper limit of the number of outer balloons 50 within the above range makes it easier for the outer balloons 50 to move less in the circumferential direction z when the balloon group 11 is expanded, making it easier for the outer balloons 50 to suppress the expansion of the inner balloon 40.

[0034] 1, 2, and 5, the number of inner balloons 40 in the longitudinal direction x is preferably greater than the number of outer balloons 50 in the longitudinal direction x. By having a greater number of inner balloons 40 than the number of outer balloons 50 in the longitudinal direction x, the outer diameter of the balloon group 11 can be more easily expanded uniformly in areas other than the concave portions of the balloon group 11 during inflation. As a result, the balloon catheter 1 can have a high inflation force of the balloon group 11.

[0035] Preferably, the inner balloons 40 are not arranged in parallel. That is, the balloon catheter 1 preferably has multiple inner balloons 40 arranged in series, but does not have multiple inner balloons 40 arranged in parallel. In other words, it is preferable that there are multiple inner balloons 40 in the longitudinal direction x, and only one inner balloon 40 in the radial direction y and the circumferential direction z. By not arranging multiple inner balloons 40 in parallel, the relative positions of the multiple expanded inner balloons 40 are less likely to shift in the radial direction y or the circumferential direction z when the balloon group 11 is inflated, making it easier to uniformly inflate the balloons 10 that make up the balloon group 11 in the radial direction y and the circumferential direction z.

[0036] It is preferable that the multiple outer balloons 50 are not arranged in series. In other words, the balloon catheter 1 preferably has multiple outer balloons 50 arranged in parallel, but does not have multiple outer balloons 50 arranged in series. In other words, it is preferable that there are multiple outer balloons 50 in the radial direction y and the circumferential direction z, and there is only one outer balloon 50 in the longitudinal direction x. By not arranging multiple outer balloons 50 in series, the outer balloon 50 is more likely to expand in diameter throughout the entire longitudinal direction x when the balloon group 11 is inflated, thereby increasing the inflation force of the balloon catheter 1.

[0037] 2, the length L40 from the distal end 40d of the inner balloon 40 to the proximal end 40p of the inner balloon 40 when the inner balloon 40 is in an inflated state is preferably shorter than the length L50 from the distal end 50d of the outer balloon 50 to the proximal end 50p of the outer balloon 50 when the outer balloon 50 is in an inflated state. When the length L40 of the inner balloon 40 is shorter than the length L50 of the outer balloon 50, it becomes easier to increase the expansion force of the portion where the inner balloon 40 is located while forming a concave portion in the balloon group 11. As a result, expansion can be performed efficiently while preventing displacement of the balloon group 11.

[0038] The length L40 from the distal end 40d of the inner balloon 40 to the proximal end 40p of the inner balloon 40 when the inner balloon 40 is in an inflated 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 of the outer balloon 50 to the proximal end 50p of the outer balloon 50 when the outer balloon 50 is in an inflated state. 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 when in an inflated state within the above range, the total length of all of the inner balloons 40 in the longitudinal direction x can be prevented from becoming too long, resulting in a balloon catheter 1 that is easy to handle. Furthermore, the length L40 from the distal end 40d of the inner balloon 40 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 of the outer balloon 50 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 within the above range, the expansion force of the entire balloon group 11 can be easily increased.

[0039] In the expanded state, the length L40 from the distal end 40d of each of the multiple inner balloons 40 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 is preferably the same. That is, when the balloon group 11 is expanded, the length L40 of each of the multiple inner balloons 40 included in the balloon group 11 is preferably the same. Having the same length L40 of each of the multiple inner balloons 40 included in the balloon catheter 1 means that the lengths L40 of each of the multiple inner balloons 40 are approximately the same. Specifically, the length L40 of one inner balloon 40 is between 90% and 110% of the maximum length L40 of all the other inner balloons 40. Having the same length L40 of each of the multiple inner balloons 40 included in the balloon catheter 1 when the balloon group 11 is expanded makes it easier to align the expansion points of all the inner balloons 40, making it easier to adjust the expansion of the balloon group 11.

[0040] In the expanded state, the length L50 from the distal end 50d of each of the outer balloons 50 to the proximal end 50p of each of the outer balloons 50 in the longitudinal direction x of the balloon catheter 1 may be different, but is preferably the same. That is, when the balloon group 11 is expanded, the length L50 of each of the outer balloons 50 included in the balloon group 11 is preferably the same. The fact that the length L50 from the distal end 50d of each of the outer balloons 50 to the proximal end 50p of each of the outer balloons 50 in the longitudinal direction x of the balloon catheter 1 is the same means that the length L50 of each of the outer balloons 50 in the longitudinal direction x of the balloon group 11 is approximately the same. Specifically, this means that the length L50 of one outer balloon 50 in the longitudinal direction x is between 90% and 110% of the length L50 of all of the other outer balloons 50 in the longitudinal direction x. When the balloon group 11 is expanded, the length L50 in the longitudinal direction x of the multiple outer balloons 50 of the balloon catheter 1 is the same, which makes it easier to synchronize the expansion timing of all the outer balloons 50, making it easier to control the expansion of the balloon group 11.

[0041] Although not shown, the multiple inner balloons 40 preferably include a distal inner balloon 41 and a proximal inner balloon 42 adjacent to the distal inner balloon 41, with a gap between the distal inner balloon 41 and the proximal inner balloon 42 in the longitudinal direction x. That is, the balloon catheter 1 preferably has at least two inner balloons 40, the distal inner balloon 41 and the proximal inner balloon 42, with the proximal inner balloon 42 being spaced apart from the distal inner balloon 41 in the longitudinal direction x. By providing a gap between the distal inner balloon 41 and the proximal inner balloon 42, the depth of the recessed shape formed in the balloon group 11 can be increased, making it easier for the balloon group 11 to grasp a stenotic region, a biological valve, or the like, and reducing the likelihood of the balloon group 11 becoming displaced.

[0042] The portion where the gap between the distal inner balloon 41 and the proximal inner balloon 42 is located in the longitudinal direction x preferably includes the midpoint P2 of the length L50 of the outer balloon 50 in the longitudinal direction x. In other words, the gap between the distal inner balloon 41 and the proximal inner balloon 42 is preferably located at the position where the midpoint P2 of the length L50 of the outer balloon 50 in the longitudinal direction x exists. By including the midpoint P2 of the length L50 of the outer balloon 50 in the portion 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 located in the center of the balloon group 11. As a result, a concave shape is formed in the center of the balloon group 11 when the balloon group 11 is inflated, making it easier to apply a load evenly from both sides of the stenosis, biological valve, etc., by the balloon group 11 while grasping the stenosis, biological valve, etc. at the center of the balloon group 11.

[0043] 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 in an expanded state, making it possible to apply a load more evenly from both sides of a stenosis, a biological valve, etc. that is grasped by the concave shape.

[0044] 2 and 5 , the multiple inner balloons 40 include a distal-most inner balloon 43 disposed most distally and a proximal-most inner balloon 44 disposed most proximally, and it is preferable that the distal end 43d of the distal-most inner balloon 43 is located proximal to the distal end 50d of the outer balloon 50, and the proximal end 44p of the proximal-most inner balloon 44 is located distal to the proximal end 50p of the outer balloon 50. Because the distal end 43d of the distal-most inner balloon 43 is located proximal to the distal end 50d of the outer balloon 50 and the proximal end 44p of the proximal-most inner balloon 44 is located distal to the proximal end 50p of the outer balloon 50, the total length L40 of all the inner balloons 40 in the longitudinal direction x is shorter than the length L50 of the outer balloon 50, and the total length 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 most proximal 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 in a deflated state.

[0045] The multiple inner balloons 40 may consist of a distal-most inner balloon 43 and a proximal-most inner balloon 44, or may further include inner balloons 40 that are different from the distal-most inner balloon 43 and the proximal-most inner balloon 44.

[0046] During inflation, the length in the longitudinal direction x from the distal end 43d of the distal-most inner balloon 43 to the proximal end 44p of the proximal-most inner balloon 44 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 distal-most inner balloon 43 to the proximal end 44p of the proximal-most inner balloon 44 to the length L50 of the outer balloon 50 within the above range, a balloon catheter 1 can be obtained that can easily and accurately apply high pressure to the target location. Furthermore, during inflation, the length in the longitudinal direction x from the distal end 43d of the distal-most inner balloon 43 to the proximal end 44p of the proximal-most inner balloon 44 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 distal-most inner balloon 43 to the proximal end 44p of the proximal-most 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 using the balloon catheter 1, making it easier to dilate a stenotic site or deform or destroy a biological valve.

[0047] The distance in the longitudinal direction x from the distal end 43d of the distal-most inner balloon 43 to the distal end 50d of the outer balloon 50 is preferably approximately the same as the distance in the longitudinal direction x from the proximal end 44p of the proximal-most inner balloon 44 to the proximal end 50p of the outer balloon 50. In other words, the distance in the longitudinal direction x from the distal end 43d of the distal-most inner balloon 43 to the distal end 50d of the outer balloon 50 is preferably 90% or more and 110% or less of the distance in the longitudinal direction x from the proximal end 44p of the proximal-most inner balloon 44 to the proximal end 50p of the outer balloon 50. Since the distance from the distal end 43d of the most distal inner balloon 43 to the distal end 50d of the outer balloon 50 is approximately the same as the distance from the proximal end 44p of the most proximal inner balloon 44 to the proximal end 50p of the outer balloon 50, the expansion of the outer balloon 50 is more easily suppressed by the multiple inner balloons 40, thereby increasing the expansion force of the balloon group 11 and making it easier to efficiently expand stenotic areas, biological valves, etc.

[0048] In the expanded state, the maximum outer diameters of the multiple inner balloons 40 of the balloon catheter 1 may be different or the same. That is, when the balloon group 11 is expanded, the maximum outer diameters of the multiple inner balloons 40 included in the balloon group 11 may be different or the same. The multiple inner balloons 40 of the balloon catheter 1 having the same maximum outer diameter means that the maximum outer diameters of the multiple inner balloons 40 are approximately the same, and more specifically, means that the maximum outer diameter of one inner balloon 40 is between 90% and 110% of the maximum outer diameters of all the other inner balloons 40.

[0049] 5, the maximum outer diameter D41 of the distal inner balloon 41 in its inflated state is preferably larger than the maximum outer diameter D42 of the proximal inner balloon 42 in its inflated state. When the inner balloon 40 is in its inflated state, the maximum outer diameter D41 of the distal inner balloon 41 is larger than the maximum outer diameter D42 of the proximal inner balloon 42. As a result, the distal portion of the entire inner balloon 40, including the multiple inner balloons 40, expands more than the proximal portion. As a result, the distal side of the balloon group 11 expands more than the proximal side, and the balloon group 11 is more likely to get caught on a stenosis, a biological valve, or the like, making it less likely to become displaced.

[0050] The maximum outer diameter D41 of the distal inner balloon 41 in the inflated state is preferably at least 1.15 times, more preferably at least 1.20 times, and even more preferably at least 1.25 times, the maximum outer diameter D42 of the proximal inner balloon 42 in the inflated state. By setting the lower limit of the ratio of the maximum outer diameter D41 of the distal inner balloon 41 to the maximum outer diameter D42 of the proximal inner balloon 42 in the inflated state within the above range, the difference between the outer diameters of the distal and proximal portions of the multiple inner balloons 40 as a whole becomes larger, making it easier for the balloon group 11 in the inflated state to get caught on a stenosis, a biological valve, or the like. Furthermore, the maximum outer diameter D41 of the distal inner balloon 41 in the inflated state is preferably at most 3.0 times, more preferably at most 2.8 times, and even more preferably at most 2.5 times, the maximum outer diameter D42 of the proximal inner balloon 42 in the inflated state. By setting the upper limit of the ratio between the maximum outer diameter D41 of the distal inner balloon 41 and the maximum outer diameter D42 of the proximal inner balloon 42 in the expanded state within the above range, the distal side of the balloon group 11 is less likely to become excessively large compared to the proximal side.

[0051] It is also preferable that the maximum outer diameter D41 of the distal inner balloon 41 in its inflated state be larger than the outer diameter of the entire proximal inner balloon 42 in the longitudinal direction x in its inflated state. When the inner balloon 40 is inflated, the maximum outer diameter D41 of the distal inner balloon 41 is larger than the outer diameter of the entire proximal inner balloon 42, making it easier for the distal portion of the balloon group 11 to expand more than the proximal portion. Therefore, when the balloon group 11 is used to expand a stenosis, a biological valve, or the like, the balloon group 11 is more likely to catch on the stenosis, the biological valve, or the like, allowing for efficient expansion while preventing displacement.

[0052] 3 and 4, it is preferable that the outer surfaces of at least one pair of adjacent outer balloons 50 are in contact with each other when the outer balloons 50 are in an expanded state. Since at least one pair of adjacent outer balloons 50 are in contact with each other when the outer balloons 50 are in an expanded state, the adjacent outer balloons 50 suppress each other's expansion when a fluid is introduced into the balloon 10 to expand it. This increases the pressure of the fluid introduced into the lumen of the multiple outer balloons 50, increasing the hardness of the multiple outer balloons 50 and increasing the expansion force.

[0053] In the expanded state, all outer balloons 50 of the balloon catheter 1 are preferably in contact with adjacent outer balloons 50. Specifically, in the case of a balloon catheter 1 configured as shown in Fig. 3, each outer balloon 50 is preferably in contact with the outer balloons 50 located on both sides of the outer balloon 50 in the circumferential direction z. In the expanded state of the outer balloons 50, all outer balloons 50 of the balloon catheter 1 are in contact with adjacent outer balloons 50. As a result, when the balloon 10 is expanded, all outer balloons 50 mutually suppress the expansion of each other, and the internal pressure of all outer balloons 50 increases. This increases the hardness of the entire balloon 10, further increasing the expansion force.

[0054] As shown in FIGS. 3 and 4 , when the inner balloon 40 and the outer balloon 50 are inflated, the outer balloon 50 preferably contacts the outer peripheral surface of the inner balloon 40. That is, when the balloon 10 is inflated, at least one of the outer balloons 50 of the balloon catheter 1 preferably contacts the outer surface of at least one of the inner balloons 40. In the inflated state, the outer balloon 50 contacts the outer peripheral surface of the inner balloon 40, which makes it easier for the inner balloon 40 and the outer balloon 50 to mutually suppress each other's expansion during inflation of the balloon 10. As a result, both the inner balloon 40 and the outer balloon 50 are less likely to inflate, which makes it easier to increase the inflation force of the balloon 10. Furthermore, since the inner balloon 40 and the outer balloon 50 mutually suppress their expansion, this also has the effect of preventing the inner balloon 40 and the outer balloon 50 from being over-expanded when a fluid is introduced into both the inner balloon 40 and the outer balloon 50 to create a high-pressure state.

[0055] It is more preferable that, when the balloon 10 is inflated, all of the outer balloons 50 of the balloon catheter 1 are in contact with the outer peripheral surface of the inner balloon 40. When the balloon 10 is inflated, all of the outer balloons 50 of the balloon catheter 1 are in contact with the outer peripheral surface of the inner balloon 40, which increases the effect of the inner balloon 40 and the outer balloon 50 in suppressing each other's expansion, making it easier to further increase the expansion force of the balloon 10.

[0056] 1 to 5, the balloon catheter 1 preferably further includes a shaft 70 having a longitudinal direction x. The distal portion of the shaft 70 is connected to the inner balloon 40 and the outer balloon 50, and the fluid that inflates and deflates the inner balloon 40 and the outer balloon 50 is preferably introduced and discharged through the lumen of the shaft 70.

[0057] The shaft 70 is preferably made of resin, metal, or a combination of resin and metal. Using resin as the material for the shaft 70 makes it easier to impart flexibility and elasticity to the shaft 70. Furthermore, using metal as the material for the shaft 70 can improve the deliverability of the balloon catheter 1. Examples of resins that can be used for the shaft 70 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluorine-containing resins, vinyl chloride resins, silicone resins, natural rubber, and synthetic rubber. These materials may be used alone or in combination. Examples of metals that can be used for the shaft 70 include stainless steels such as SUS304 and SUS316, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, Ni-Ti alloys, Co-Cr alloys, and combinations thereof. The shaft 70 may also have a layered structure made of different or the same materials.

[0058] 1 shows a so-called rapid exchange type balloon catheter 1 having a guidewire port 191 midway from the distal side to the proximal side of the shaft 70 and a guidewire tube 192 that functions as a guidewire passage from the guidewire port 191 to the distal side of the shaft 70. When the balloon catheter 1 is a rapid exchange type, the balloon catheter 1 preferably has a distal shaft 75 and a proximal shaft 76. The distal shaft 75 and the proximal shaft 76 may be separate members, and the proximal end of the distal shaft 75 may be connected to the distal end of the proximal shaft 76 to form the shaft 70 that extends from the balloon 10 to the proximal end of the balloon catheter 1. When the shaft 70 is composed of the distal shaft 75 and the proximal shaft 76 that are separate members, the distal shaft 75 may be made of resin and the proximal shaft 76 may be made of metal, for example. 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 made up of multiple tubular members.

[0059] Alternatively, although not shown, the present invention can also be applied to a so-called over-the-wire balloon catheter, which has a guidewire passage extending from the distal side to the proximal side of the shaft. When the balloon catheter is an over-the-wire type, it is preferable that the inflation lumen and the guidewire lumen extend to a hub located on the proximal side, and that the proximal openings of each lumen are provided in a bifurcated hub.

[0060] It is preferable that the shaft 70 has a fluid flow path and a guidewire insertion path therein. For example, a configuration in which the shaft 70 has a fluid flow path and a guidewire insertion path therein can be achieved by configuring the guidewire tube 192 disposed inside the shaft 70 to function as the guidewire insertion path, and the space between the shaft 70 and the guidewire tube 192 to function as a fluid flow path. In such a configuration, it is preferable that the guidewire tube 192 extends from the distal end of the shaft 70 and passes through the balloon 10, with the distal side of the balloon 10 connected to the guidewire tube 192 and the proximal side of the balloon 10 connected to the shaft 70.

[0061] The shaft 70 has a first lumen, which is a fluid flow path, and is disposed 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 disposed in the lumen of the proximal inner balloon 42 and connected to the distal inner balloon 41, 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, the distal inner balloon 41 can be inflated before the proximal inner balloon 42. Therefore, a stenosis, a biological valve, or the like can be inflated while the position of the balloon 10 in the biological lumen is fixed by the distal inner balloon 41, and displacement of the balloon 10 during inflation is less likely to occur.

[0062] The shaft 70 may further have a second lumen which is a fluid flow path, and the second lumen may be in communication with the inner cavity of the outer balloon 50. By the shaft 70 further having a second lumen which is in communication with the inner cavity of the outer balloon 50, it becomes possible to stagger the timing at which the inner balloon 40 and the outer balloon 50 expand and contract.

[0063] 5 , when the distal-most inner balloon 43 is in an inflated state, the maximum outer diameter D43d of the distal portion of the distal-most inner balloon 43 is preferably larger than the maximum outer diameter D43p of the proximal portion of the distal-most inner balloon 43. The distal portion of the distal-most inner balloon 43 refers to the distal portion of the distal-most inner balloon 43 when the distal-most inner balloon 43 is bisected in the longitudinal direction x, and the proximal portion of the distal-most inner balloon 43 refers to the proximal portion of the distal-most inner balloon 43 when the distal-most inner balloon 43 is bisected in the longitudinal direction x. When the distal-most inner balloon 43 is in an inflated state, the maximum outer diameter D43d of the distal portion of the distal-most inner balloon 43 is larger than the maximum outer diameter D43p of the proximal portion, thereby allowing the outer diameter of the inner balloon 40 to be small in the central portion of the balloon group 11. Therefore, the depth of the recessed shape in the center of the balloon group 11 can be increased, and the recessed portion can easily grasp the stenotic area, biological valve, etc.

[0064] When the distal-most inner balloon 43 is in an inflated state, the maximum outer diameter D43d of the distal portion of the distal-most inner balloon 43 is preferably at least 1.2 times, more preferably at least 1.3 times, and even more preferably at least 1.4 times, the maximum outer diameter D43p of the proximal portion of the distal-most inner balloon 43. By setting the lower limit of the ratio of the maximum outer diameter D43d of the distal portion of the distal-most inner balloon 43 to the maximum outer diameter D43p of the proximal portion of the distal-most inner balloon 43 in an inflated state within the above range, the difference in outer diameter between the distal and proximal portions of the distal-most inner balloon 43 can be increased, thereby deepening the concave shape of the balloon group 11. Furthermore, when the distal-most inner balloon 43 is in an inflated state, the maximum outer diameter D43d of the distal portion of the distal-most inner balloon 43 is preferably at most 5.0 times, more preferably at most 4.5 times, and even more preferably at most 4.0 times, the maximum outer diameter D43p of the proximal portion of the distal-most inner balloon 43. By setting the upper limit of the ratio between the maximum outer diameter D43d of the distal portion of the most distal inner balloon 43 in the expanded state and the maximum outer diameter D43p of the proximal portion within the above range, the outer diameter of the balloon group 11 at both ends of the concave portion of the balloon group 11 can be increased, thereby improving the effect of expanding stenotic areas, biological valves, etc.

[0065] The distal-most inner balloon 43 preferably has a tapered shape with an outer diameter increasing distally. That is, the distal-most inner balloon 43 is preferably a so-called tapered balloon. By having the distal-most inner balloon 43 have a tapered shape with an outer diameter increasing distally, a deep concave portion can be easily formed in the balloon group 11, and the expansion force of the balloon group 11 can be easily increased at both ends of the concave portion.

[0066] As shown in FIG. 5 , when the proximal-most inner balloon 44 is inflated, the maximum outer diameter D44p of the proximal portion of the proximal-most inner balloon 44 is preferably larger than the maximum outer diameter D44d of the distal portion of the proximal-most inner balloon 44. The proximal portion of the proximal-most inner balloon 44 refers to the portion of the proximal-most inner balloon 44 that is located on the proximal side when the proximal-most inner balloon 44 is bisected in the longitudinal direction x. The distal portion of the proximal-most inner balloon 44 refers to the portion of the proximal-most inner balloon 44 that is located on the distal side when the proximal-most inner balloon 44 is bisected in the longitudinal direction x. When the proximal-most inner balloon 44 is inflated, the maximum outer diameter D44p of the proximal portion of the proximal-most inner balloon 44 is larger than the maximum outer diameter D44d of the distal portion. This allows the outer diameter of the inner balloon 40 to be reduced in the central portion of the balloon group 11, thereby increasing the depth of the concave shape in the central portion of the balloon group 11. This makes it easier to grasp a stenotic region, a biological valve, or the like in the concave portion of the balloon group 11.

[0067] When the proximal-most inner balloon 44 is in an inflated state, the maximum outer diameter D44p of the proximal portion of the proximal-most inner balloon 44 is preferably at least 1.2 times, more preferably at least 1.3 times, and even more preferably at least 1.4 times, the maximum outer diameter D44d of the distal portion of the proximal-most inner balloon 44. By setting the lower limit of the ratio of the maximum outer diameter D44p of the proximal portion of the proximal-most inner balloon 44 to the maximum outer diameter D44d of the distal portion of the proximal-most inner balloon 44 in an inflated state within the above range, the difference between the outer diameters of the proximal and distal portions of the proximal-most inner balloon 44 becomes larger, thereby increasing the depth of the concave shape of the balloon group 11. Furthermore, when the proximal-most inner balloon 44 is in an inflated state, the maximum outer diameter D44p of the proximal portion of the proximal-most inner balloon 44 is preferably at most 5.0 times, more preferably at most 4.5 times, and even more preferably at most 4.0 times the maximum outer diameter D44d of the distal portion of the proximal-most inner balloon 44. By setting the upper limit of the ratio between the maximum outer diameter D44p of the proximal portion of the most proximal inner balloon 44 in the expanded state and the maximum outer diameter D44d of the distal portion within the above range, it becomes easier to increase the outer diameter of the balloon group 11 at both ends of the concave portion, thereby increasing the expansion force on stenotic areas, biological valves, etc.

[0068] The proximal-most inner balloon 44 preferably has a tapered shape with an outer diameter increasing proximally. That is, the proximal-most inner balloon 44 is preferably a so-called tapered balloon. By having the proximal-most inner balloon 44 have a tapered shape with an outer diameter increasing proximally, it is easy to increase the depth of the concave shape of the balloon group 11, and the balloon group 11 can be expanded greatly at both ends of the concave portion, allowing for efficient expansion.

[0069] The shaft 70 has a guidewire lumen 93 extending in the longitudinal direction x and through which a guidewire is inserted, and further has a guidewire tube 192 having an inner cavity communicating with the guidewire lumen 93, and the guidewire tube 192 is preferably disposed in the inner cavity of the inner balloon 40. Since the balloon catheter 1 has the guidewire tube 192 having an inner cavity communicating with the guidewire lumen 93, it becomes easy to insert the guidewire into the balloon catheter 1, and the balloon catheter 1 can be delivered into the body along the guidewire. Furthermore, by inserting the guidewire into the guidewire tube 192, it is possible to prevent the guidewire from damaging the balloon 10, etc.

[0070] Examples of materials constituting the guidewire tube 192 include synthetic resins such as polyolefin resins (e.g., polyethylene, polypropylene, etc.), polyamide resins (e.g., nylon, etc.), polyester resins (e.g., PET, etc.), aromatic polyetherketone resins (e.g., PEEK, etc.), polyetherpolyamide resins, polyurethane resins, polyimide resins, fluorine-containing resins (e.g., PTFE, PFA, ETFE, etc.), and polyvinyl chloride resins. Among these, polyimide resins are preferred as the material constituting the guidewire tube 192. Using polyimide resin as the material constituting the guidewire tube 192 improves the lubricity of the guidewire tube 192. This facilitates inserting a guidewire through the lumen of the guidewire tube 192 and feeding the balloon catheter 1 into the body along the guidewire. The guidewire tube 192 may also have a multi-layer structure including a braided layer (e.g., a metal braid). The multi-layer structure of the guidewire tube 192 enhances the strength of the guidewire tube 192, its lubricity relative to the guidewire, and its kink resistance.

[0071] 1, the proximal end of the guidewire tube 192 is preferably connected to the distal end of the shaft 70. When the shaft 70 has a distal shaft 75 and a proximal shaft 76, the proximal end of the guidewire tube 192 is preferably connected to the distal end of the distal shaft 75. Connecting the proximal end of the guidewire tube 192 to the distal end of the shaft 70 prevents the outer diameter of the balloon catheter 1 from becoming large, thereby improving minimal invasiveness.

[0072] The balloon 10 and the shaft 70 can be joined by bonding with an adhesive, welding, or by attaching a ring-shaped member to the overlapping portion of the end of the balloon 10 and the shaft 70 and crimping them. Among these, 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 bond between the balloon 10 and the shaft 70 is less likely to come loose even when the balloon 10 is repeatedly expanded or contracted, and the bond strength can be improved.

[0073] A tip member 193 is preferably 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 as a separate member from the guidewire tube 192 by being connected to the distal end of the balloon 10, or the guidewire tube 192 extending distally of the distal end of the balloon 10 may function as the tip member 193.

[0074] As shown in Figures 1, 2 and 5, a radiopaque marker 194 may be placed on the guidewire tube 192 inside the balloon 10 at the location where the balloon 10 is located in the longitudinal axis direction x so that the position of the balloon 10 can be confirmed under X-ray fluoroscopy.

[0075] Examples of the position on the guidewire tube 192 at which the radiopaque marker 194 is disposed include 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 proximal and distal ends of the straight tube portion 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 most proximal inner balloon 44, the proximal end of the straight tube portion of the most distal inner balloon 43 and the distal end of the straight tube portion of the most proximal inner balloon 44, and the proximal and distal ends of the straight tube portion of the outer balloon 50. Among these, the position on the guidewire tube 192 at which the radiopaque marker 194 is disposed is preferably the proximal end of the straight tube portion of the most distal inner balloon 43 and the distal end of the straight tube portion of the most proximal inner balloon 44. The radiopaque markers 194 are disposed on the guidewire tube 192 at the proximal end of the straight tube portion of the most distal inner balloon 43 and the distal end of the straight tube portion of the most proximal inner balloon 44, making it easier to confirm the portion where a concave shape will be formed in the balloon 10. As a result, the balloon catheter 1 can be made such that the concave portion can easily grasp a stenosis or a biological valve, etc., and is less likely to become displaced.

[0076] 1, a hub 5 may be provided on the proximal side of the shaft 70. The hub 5 may also be provided with a fluid injecting section 6 that communicates with a flow path for fluid supplied to the inside of the balloon 10.

[0077] The shaft 70 and the hub 5 can be joined by, for example, bonding with an adhesive or welding. Among these, it is preferable that the shaft 70 and the hub 5 are joined by adhesive. By joining the shaft 70 and the hub 5 by adhesive, the bond strength between the shaft 70 and the hub 5 can be increased and the durability of the balloon catheter 1 can be improved when the shaft 70 and the hub 5 are made of different materials, for example, when the shaft 70 is made of a highly flexible material and the hub 5 is made of a highly rigid material.

[0078] When the balloon catheter 1 is a rapid exchange type, a coating may be applied to the outer wall of at least one of the distal shaft 75 and the proximal shaft 76, or may be applied to the outer walls of both the distal shaft 75 and the proximal shaft 76. When the balloon catheter 1 is an over-the-wire type, a coating may be applied to the outer wall of the outer shaft.

[0079] The coating applied to the shaft 70 can be a hydrophilic coating or a hydrophobic coating depending on the purpose, and 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 drugs or additives.

[0080] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, methyl vinyl ether maleic anhydride copolymer, and the like, or hydrophilic coating agents made from any combination thereof.

[0081] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), 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.

[0082] The balloon catheter 1 of the present invention is preferably used for dilating an aortic valve, deforming a biological valve placed in the heart, or destroying a biological valve. Specifically, the balloon catheter 1 of the present invention is preferably used for dilating an aortic valve that has hardened due to calcification or the like, or for deforming or destroying an artificial valve annulus of a biological valve to replace a deteriorated biological valve placed in the heart. The balloon catheter 1 of the present invention is preferably used because it is easy to apply high pressure to the portion where the inner balloon 40 is located, and therefore is easily able to dilate a hardened aortic valve and deform or destroy a biological valve that cannot be sufficiently dilated with conventional balloon catheters. [Explanation of symbols]

[0083] 1: Balloon catheter 5: Hub 6:Fluid injection part 10: Balloon 11: Balloon group 40: Inner balloon 40d: Distal end of inner balloon 40p: Proximal end of inner balloon 41: Distal inner balloon 42: Proximal inner balloon 43: Most distal inner balloon 43d: Distal end of the most distal inner balloon 43p: Proximal end of the most distal inner balloon 44: Most proximal medial balloon 44d: Distal end of most proximal inner balloon 44p: Proximal end of most proximal inner balloon 50: Outer balloon 50d: Distal end of outer balloon 50p: Proximal end of outer balloon 70: Shaft 75: Distal shaft 76: Proximal shaft 93: Guidewire lumen 191: Guidewire port 192: Guidewire tube 193: Tip tip component 194: Radiopaque marker P2: Midpoint of the length of the outer balloon L40: Length of inner balloon L50: Length of outer balloon D41: Maximum outer diameter of the distal inner balloon D42: Maximum outer diameter of the proximal inner balloon D43d: Maximum outer diameter of the distal part of the most distal inner balloon D43p: Maximum outer diameter of the proximal part of the most distal inner balloon D44d: Maximum outer diameter of the distal part of the most proximal inner balloon D44p: Maximum outer diameter of the proximal part of the most proximal inner balloon

Claims

1. a plurality of inner balloons arranged in series with one another; A balloon catheter having a plurality of outer balloons arranged in parallel to each other radially outward of the inner balloon.

2. 2. The balloon catheter according to claim 1, wherein the number of the inner balloons in the longitudinal direction is greater than the number of the outer balloons in the longitudinal direction.

3. 2. The balloon catheter according to claim 1, wherein a length from a distal end of the inner balloon to a proximal end of the inner balloon when the inner balloon is in an inflated state is shorter than a length from a distal end of the outer balloon to a proximal end of the outer balloon when the outer balloon is in an inflated state.

4. the plurality of inner balloons include a distal inner balloon and a proximal inner balloon adjacent to the distal inner balloon; 2. The balloon catheter according to claim 1, wherein a gap is formed between the distal inner balloon and the proximal inner balloon in the longitudinal direction.

5. 5. The balloon catheter according to claim 4, wherein the portion where the gap between the distal inner balloon and the proximal inner balloon is located in the longitudinal direction includes a midpoint of the length of the outer balloon in the longitudinal direction.

6. the plurality of inner balloons include a distal-most inner balloon disposed most distally and a proximal-most inner balloon disposed most proximally; a distal end of the most distal inner balloon is located proximal to a distal end of the outer balloon; 2. The balloon catheter according to claim 1, wherein the proximal end of the most proximal inner balloon is located distal to the proximal end of the outer balloon.

7. the plurality of inner balloons include a distal inner balloon and a proximal inner balloon adjacent to the distal inner balloon; 2. The balloon catheter according to claim 1, wherein a maximum outer diameter of the distal inner balloon in an inflated state is greater than a maximum outer diameter of the proximal inner balloon in an inflated state.

8. a shaft having a longitudinal direction; the plurality of inner balloons include a distal inner balloon and a proximal inner balloon adjacent to the distal inner balloon; The shaft has a first lumen that is a fluid flow path, the shaft is disposed within a lumen of the proximal inner balloon and is connected to the distal inner balloon; the first lumen communicates with the lumen of the distal inner balloon; The balloon catheter according to claim 1 , wherein the lumen of the distal inner balloon communicates with the lumen of the proximal inner balloon.

9. the plurality of inner balloons include a distal-most inner balloon disposed most distally and a proximal-most inner balloon disposed most proximally; 2. The balloon catheter according to claim 1, wherein, in the inflated state of the distal-most inner balloon, a maximum outer diameter of a distal portion of the distal-most inner balloon is greater than a maximum outer diameter of a proximal portion of the distal-most inner balloon.

10. the plurality of inner balloons include a distal-most inner balloon disposed most distally and a proximal-most inner balloon disposed most proximally; 2. The balloon catheter according to claim 1, wherein, in the inflated state of the proximal-most inner balloon, a maximum outer diameter of a proximal portion of the proximal-most inner balloon is greater than a maximum outer diameter of a distal portion of the proximal-most inner balloon.

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