Balloon catheter

Abstract

The present invention provides a less invasive balloon catheter having a smaller outer diameter of a portion having a plurality of balloons arranged in a contracted state. A balloon catheter (1) has a group (11) of balloons including a plurality of balloons (10) arranged in parallel with each other in a circumferential direction z. When the group (11) of balloons are in a contracted state, each balloon (10) has a first fold part (21) and a second fold part (22), which are two fold parts (20) in the circumferential direction z, and a non-fold part (30), which is a part other than the fold parts (20), the first fold part (21) being positioned at an end of each balloon (10) on one side in the circumferential direction z, and the second fold part (22) being positioned at an end of each balloon (10) on the other side in the circumferential direction z.

Description

Balloon catheter

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

[0002] The formation of hardened stenotic areas due to calcification and other factors on the inner walls of blood vessels can lead to diseases such as angina pectoris and myocardial infarction. One of the treatments for these conditions is angioplasty, which uses a balloon catheter to dilate the stenotic 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 surgical open-chest surgery and catheter placement to replace the hardened aortic valve with a biological valve (artificial 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 a braided balloon catheter or multiple balloon catheters, causing it to deform or break, and then expanding the valve lumen, followed by implanting a new bioprosthetic valve inside the deformed or broken bioprosthetic valve using techniques such as transcatheter aortic valve replacement.

[0005] As balloon catheters used for dilating hardened stenotic lesions or placing biological valves, for example, Patent Document 1 discloses a catheter 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 are separated 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.

[0006] Japanese Patent Publication No. 03-013907 U.S. Patent Application Publication No. 2012 / 0209375 JP 2018-175550 A JP 2018-536474 A International Publication No. 2021 / 054189

[0007] However, because the conventional balloon catheters described above have multiple balloons, even when the balloons are folded in a deflated state, the area where the balloons are located is bulky, making it difficult to reduce the outer diameter. In addition, the outer diameter of the sheath used to transport the balloon catheter to the treatment site also becomes large, resulting in high invasiveness.

[0008] In view of the above circumstances, an object of the present invention is to provide a balloon catheter that can reduce the outer diameter of the portion where multiple balloons are arranged in a deflated state, thereby reducing invasiveness.

[0009] The following balloon catheters according to embodiments of the present invention have solved the above-mentioned problems. [1] A balloon catheter including a balloon group including a plurality of balloons arranged parallel to one another in the circumferential direction, wherein, when the balloon group is in a deflated state, the balloons have two circumferential folds, a first fold and a second fold, and a non-fold portion excluding the first fold, the first fold being located at one circumferential end of the balloon, and the second fold being located at the other circumferential end of the balloon. [2] The balloon catheter described in [1], wherein the balloon group includes an inner balloon and a plurality of outer balloons arranged radially outward of the inner balloon, the outer balloons having the first fold, the second fold, and the non-fold portion. [3] The balloon catheter described in [2], wherein, when the balloon group is in a deflated state, the inner balloon has the fold, and the number of folds in the inner balloon is greater than the number of folds in the outer balloon. [4] The balloon catheter according to [2] or [3], wherein the inner balloon has a wing-shaped portion when the inner balloon is in a deflated state. [5] The balloon catheter according to any of [2] to [4], wherein the balloon group includes a first outer balloon and a second outer balloon adjacent to the first outer balloon on one circumferential side of the inner balloon, the first outer balloon and the second outer balloon each have the first fold portion, the second fold portion, and the non-fold portion, and when the balloon group is in a deflated state, the second fold portion of the first outer balloon is located radially inward of the inner balloon with respect to the first fold portion of the second outer balloon and on one circumferential side of the inner balloon with respect to the first fold portion of the second outer balloon.[6] The balloon catheter according to any one of [2] to [5], further comprising a shaft having a longitudinal direction, wherein in a cross section of the balloon group perpendicular to the longitudinal direction when the balloon group is in a deflated state, the shortest distance between the centroid of the shaft and the first fold portion of the outer balloon is greater than the shortest distance between the centroid of the shaft and the second fold portion of the outer balloon. [7] The balloon catheter according to any one of [1] to [6], further comprising a shaft having a longitudinal direction, wherein in a cross section of the balloon group perpendicular to the longitudinal direction when the balloon group is in a deflated state, the non-fold portion has a curved portion.

[0010] According to the balloon catheter, when the balloon group is deflated, the balloon has two circumferential folds, a first fold located at one circumferential end of the balloon and a second fold located at the other circumferential end of the balloon, as well as a non-folded portion excluding the first folds. This reduces the bulkiness of the deflated balloon and allows the outer diameter of the portion where the multiple balloons are located to be reduced, thereby making the balloon catheter even less invasive.

[0011] Fig. 1 shows an overall view of a balloon catheter according to one embodiment of the present invention. Fig. 2 shows an enlarged view of a portion of the balloon catheter shown in Fig. 1 where a balloon is disposed. Fig. 3 shows a cross-sectional view of the balloon catheter shown in Fig. 1 taken along III-III. Fig. 4 shows a cross-sectional view of the balloon catheter shown in Fig. 3 in a deflated state. Fig. 5 shows a cross-sectional view of a balloon catheter according to another embodiment of the present invention in a deflated state. Fig. 6 shows a cross-sectional view of a balloon catheter according to a different embodiment of the present invention in a deflated state.

[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, please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority 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 balloon group including a plurality of balloons arranged in parallel with one another in the circumferential direction, and when the balloon group is in a deflated state, the balloon has two circumferential folds, a first fold and a second fold, and a non-folded portion excluding the folds, with the first fold located at one circumferential end of the balloon and the second fold located at the other circumferential end of the balloon.

[0014] Balloon catheters according to embodiments of the present invention will now be described with reference to Figures 1 to 7. Figure 1 is an overall view of a balloon catheter according to one 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 of the balloon catheter shown in Figure 1 taken along line III-III, showing a cross-sectional view perpendicular to the longitudinal direction at the portion where the balloon group is present when the balloon group is in an expanded state. Figure 4 is a cross-sectional view of the balloon catheter shown in Figure 3 in a deflated state, showing a cross-sectional view perpendicular to the longitudinal direction at the portion where the balloon group is present when the balloon group is in a deflated state. Figure 5 is a cross-sectional view of a balloon catheter according to another embodiment of the present invention in a deflated state. Figure 6 is a cross-sectional view of a balloon catheter according to another embodiment of the present invention in a deflated state. Figure 7 is a cross-sectional view of a balloon catheter according to a different embodiment of the present invention in a deflated state, showing a cross-sectional view perpendicular to the longitudinal direction at the portion where the balloon group is present when the balloon group is in a deflated state.

[0015] As shown in FIGS. 1 to 7, the balloon catheter 1 has a balloon group 11 including a plurality of balloons 10 arranged in parallel with one another in the circumferential direction z.

[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 portion 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 as 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] A balloon group 11 having a plurality of balloons 10 is located at the distal portion of the balloon catheter 1. The balloons 10 can be expanded by introducing a fluid into the lumen of the balloons 10, and can be deflated by discharging the fluid from the lumen of the balloons 10. To control the expansion and contraction of the balloons 10, an indeflator (a balloon pressurizer) can be used to introduce or discharge the fluid. The fluid may 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] 4 and 5 , in the deflated state of the balloon group 11, the balloon 10 has two folds 20 in the circumferential direction z, a first fold 21 and a second fold 22, and a non-fold portion 30 excluding the folds 20. The first fold 21 is located at one end of the balloon 10 in the circumferential direction z, and the second fold 22 is located at the other end of the balloon 10 in the circumferential direction z. In other words, at least one balloon 10 constituting the balloon group 11, in the deflated state, has the first fold 21 constituting one end of the balloon 10 in the circumferential direction z, the second fold 22 constituting the other end of the balloon 10 in the circumferential direction z, and the non-fold portion 30 located between the first fold 21 and the second fold 22 in the circumferential direction z of the balloon 10.

[0021] The first fold 21 and the second fold 22 are overlapping portions of the balloon membrane that constitutes the balloon 10 when the balloon 10 is folded with the inner surface facing inward when the balloon 10 is deflated, and are lines that appear on the balloon membrane when the balloon 10 is in a folded state. In other words, when the balloon 10 is deflated, the balloon 10 is folded in two so as to extend in the circumferential direction z of the balloon 10, and the fold 20 on one side of the balloon 10 in the circumferential direction z is the first fold 21, and the fold 20 on the other side of the balloon 10 in the circumferential direction z is the second fold 22.

[0022] When the balloon group 11 is in a deflated state, the balloon 10 has two folds 20 in the circumferential direction z, a first fold 21 and a second fold 22, and a non-folded portion 30 excluding the folds 20, with the first fold 21 located at one end of the balloon 10 in the circumferential direction z and the second fold 22 located at the other end of the balloon 10 in the circumferential direction z. This configuration reduces the bulkiness of the deflated balloon 10, allowing the outer diameter of the portion of the balloon catheter 1 where the balloon group 11 is located to be reduced in the deflated state. As a result, the outer diameter can be made smaller than that of conventional balloon catheters having multiple balloons, making the balloon catheter 1 even less invasive.

[0023] 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. Since the straight tube portion has the largest diameter, 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 can sufficiently contact the lesion, facilitating treatment such as dilation of the lesion. Furthermore, since 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.

[0024] When the balloon 10 has a straight tube section, a proximal tapered section, and a distal tapered section, in at least the straight tube section of the balloon 10, the first fold section 21 is located at one end of the balloon 10 in the circumferential direction z, and the second fold section 22 is located at the other end of the balloon 10 in the circumferential direction z.

[0025] The balloon 10 preferably 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 preventing the proximal sleeve portion and distal sleeve portion from expanding, 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.

[0026] As shown in Figures 4 and 5, the balloon group 11 preferably includes an inner balloon 40 and multiple outer balloons 50 arranged radially outward of the inner balloon 40. That is, the balloon group 11 preferably includes the inner balloon 40 and multiple outer balloons 50 arranged along the outer periphery of the inner balloon 40. By including the inner balloon 40 and multiple outer balloons 50 arranged radially outward of the inner balloon 40, the multiple outer balloons 50 suppress the outward expansion of the inner balloon 40, and the inner balloon 40 suppresses the inward expansion of the multiple outer balloons 50. As a result, the inner balloon 40 and the multiple outer balloons 50 mutually suppress the expansion of each other, thereby increasing the pressure resistance of the balloon group 11 and increasing the hardness of the multiple balloons 10 constituting the balloon group 11, thereby improving the expansion force. Furthermore, the inner balloon 40 and the multiple outer balloons 50 mutually suppress the expansion of each other, making it difficult for the multiple balloons 10 constituting the balloon group 11 to inflate. Therefore, even if high pressure is applied to each of the balloons 10 that make up the balloon group 11, over-expansion of the balloons 10 is suppressed, preventing the balloon group 11 from expanding beyond the targeted outer diameter, reducing damage to the body's internal lumens such as the aortic valve and increasing safety.

[0027] The number of inner balloons 40 may be multiple, but is preferably one. That is, the balloon group 11 preferably includes one inner balloon 40 and multiple outer balloons 50. Having only one inner balloon 40 makes it difficult for the inner balloon 40 to move inside the multiple outer balloons 50 when the balloon group 11 is inflated. As a result, the inner balloon 40 is more likely to suppress the inflation of the multiple outer balloons 50, which increases the hardness of the multiple balloons 10 that make up the balloon group 11 and makes it easier to increase the inflation force. Note that the inflation of the balloon group 11 can be rephrased as the inflated state of the balloon group 11, and refers to a state in which a fluid is introduced into the lumen of each of the multiple balloons 10 that make up the balloon group 11, and all of the balloons 10 that make up the balloon group 11 are inflated.

[0028] The number of outer balloons 50 included in the balloon group 11 is preferably three or more, more preferably four or more, and even more preferably five or more. By setting the lower limit of the number of outer balloons 50 included in the balloon group 11 within the above range, it becomes easier to surround the outer periphery of the inner balloon 40 with the multiple outer balloons 50, and the outer balloons 50 are more likely 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 multiple outer balloons 50 to expand the balloon group 11, the inner balloon 40 becomes less likely to expand, and the hardness of the inner balloon 40 increases, making it easier to increase the expansion force of the balloon group 11. Furthermore, the number of outer balloons 50 included in the balloon group 11 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 contained in the balloon group 11 to the above range, the outer balloons 50 are less likely to move in the circumferential direction z when the balloon group 11 is expanded, making it easier to suppress the expansion of the inner balloon 40 by the multiple outer balloons 50.

[0029] The materials constituting the inner balloon 40 and the outer balloon 50 can be the same as those listed as materials constituting the balloon 10. The material constituting the outer balloon 50 may be the same as the material constituting the inner balloon 40 or may be different.

[0030] The materials constituting each of the multiple outer balloons 50 included in the balloon group 11 may be different, but are preferably the same. That is, 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 in the circumferential direction z can be made to be approximately the same.

[0031] When the balloon group 11 is in an expanded state, the maximum outer diameters of the multiple outer balloons 50 included in the balloon group 11 may be different, but are preferably the same. The multiple outer balloons 50 included in the balloon group 11 having the same maximum outer diameter means that the maximum outer diameters of the multiple outer balloons 50 are approximately the same, specifically, 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 in an expanded state, the multiple outer balloons 50 included in the balloon group 11 have the same maximum outer diameter, making it easier to synchronize the timing of expansion of all of the outer balloons 50 included in the balloon group 11 and to control the expansion of the balloon group 11.

[0032] When the balloon group 11 is in an expanded state, the maximum outer diameter of the inner balloon 40 may be the same as or different from the maximum outer diameter of each of the multiple outer balloons 50 included in 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 each of the multiple outer balloons 50 included in the balloon group 11 means that the maximum outer diameter of the inner balloon 40 and the maximum outer diameter of each of the multiple outer balloons 50 included in the balloon group 11 are approximately the same. Specifically, this means that the maximum outer diameter of the inner balloon 40 is 90% to 110% of the average value of the maximum outer diameters of each of the multiple outer balloons 50. When the balloon group 11 is in an expanded state, the maximum outer diameter of the inner balloon 40 is the same as the maximum outer diameter of each of the multiple outer balloons 50 included in the balloon group 11, which makes it easier to balance the force that attempts to expand the inner balloon 40 with the force that attempts to suppress the expansion of the inner balloon 40 due to the expansion of the multiple outer balloons 50. As a result, the hardness of the balloon group 11 is increased, making it easier to increase the expansion force of the balloon group 11.

[0033] When the balloon group 11 is in an expanded state, the maximum outer diameter of the inner balloon 40 is preferably larger than the maximum outer diameter of each of the multiple outer balloons 50 included in the balloon group 11. When the balloon group 11 is in an expanded state, the maximum outer diameter of the inner balloon 40 is larger than the maximum outer diameter of each of the multiple outer balloons 50 included in the balloon group 11, which makes it easier to evenly arrange the multiple outer balloons 50 along the outer periphery of the expanded inner balloon 40. Therefore, 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 at the portion where the balloon group 11 is located.

[0034] When the balloon group 11 is 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 each of the outer balloons 50 included in the balloon group 11. By setting the lower limit of the ratio of the maximum outer diameter of the inner balloon 40 to the maximum outer diameter of each of the outer balloons 50 when the balloon group 11 is inflated within the above range, the outer balloons 50 are more likely to be evenly arranged along the outer periphery 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 each of the outer balloons 50 included in the balloon group 11. By setting the upper limit of the ratio between the maximum outer diameter of the inner balloon 40 and the maximum outer diameter of each of the outer balloons 50 when the balloon group 11 is in the expanded state 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 the contracted state, making the balloon catheter 1 less invasive.

[0035] When the balloon group 11 is in an expanded state, 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 of each of the multiple outer balloons 50 included in the balloon group 11 may be different, but is preferably the same. 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 of each of the multiple outer balloons 50 included in the balloon group 11 being the same means that the lengths L50 in the longitudinal direction x of each of the multiple outer balloons 50 included in the balloon group 11 are approximately the same, and specifically means that the length L50 in the longitudinal direction x of one outer balloon 50 is 90% to 110% of the lengths L50 in the longitudinal direction x of all the other outer balloons 50. Since the length L50 in the longitudinal direction x of the multiple outer balloons 50 included in the balloon group 11 when the balloon group 11 is in an expanded state is the same, it becomes easier to align the timing at which all of the outer balloons 50 expand, making it easier to control the expansion of the balloon group 11.

[0036] When the balloon group 11 is in an inflated state, the length L40 from the distal end 40d of the inner balloon 40 to the proximal end 40p of the inner balloon 40 in the longitudinal direction x 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 in the longitudinal direction x. By making the length L40 of the inner balloon 40 shorter than the length L50 of the outer balloon 50, the inner balloon 40 is restrained by the outer balloon 50, making it less likely for the inner balloon 40 to shift position when the balloon group 11 is in an inflated state. This makes it easier for the balloon group 11 to expand more in the area where the inner balloon 40 is present than in the area where the inner balloon 40 is not present, making it easier to apply pressure to the area where the inner balloon 40 is present, and enabling accurate application of pressure to the target location. Furthermore, the balloon group 11 is less likely to expand more in the area where the inner balloon 40 is not present, making it harder to apply pressure, making it less likely for stress to be applied to areas other than the target location, thereby improving the minimally invasive nature of the balloon catheter 1.

[0037] When the balloon group 11 is in an expanded state, the length L40 from the distal end 40d of the inner balloon 40 to the proximal end 40p of the inner balloon 40 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 L40 of the inner balloon 40 to the length L50 of the outer balloon 50 within the above range, the balloon catheter 1 can be made to easily apply high pressure accurately to the target location. Furthermore, when the balloon group 11 is in an expanded state, the length L40 from the distal end 40d of the inner balloon 40 to the proximal end 40p of the inner balloon 40 in the longitudinal direction x is preferably at least 20%, more preferably at least 25%, and even more preferably at least 30% 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 L40 of the inner balloon 40 to the length L50 of the outer balloon 50 within the above range, it becomes easier to apply pressure over a sufficient area with the balloon catheter 1, making it easier to efficiently dilate a stenotic site and deform or destroy a biological valve.

[0038] 2 , it is preferable that the distal end 40d of the inner balloon 40 is located proximal to the distal end 50d of the outer balloon 50, and that the proximal end 40p of the inner balloon 40 is located distal to the proximal end 50p of the outer balloon 50. By configuring the distal end 40d of the inner balloon 40 to be proximal to the distal end 50d of the outer balloon 50 and the proximal end 40p of the inner balloon 40 to be distal to the proximal end 50p of the outer balloon 50, the distal end of the inner balloon 40 and the proximal end of the outer balloon 50 are less likely to overlap. Also, the proximal end of the inner balloon 40 and the proximal end of the outer balloon 50 are less likely to overlap. As a result, when the balloon group 11 is in a deflated state, the outer diameter of the portion of the balloon catheter 1 where the balloon group 11 is located can be easily reduced.

[0039] When the balloon group 11 is in an expanded state, it is preferable that the distal end of the distal tapered portion of the inner balloon 40 is proximal to the proximal end of the distal tapered portion of the outer balloon 50, and that the proximal end of the proximal tapered portion of the inner balloon 40 is distal to the distal end of the proximal tapered portion of the outer balloon 50. Since the distal end of the distal tapered portion of the inner balloon 40 is proximal to the proximal end of the distal tapered portion of the outer balloon 50 and the proximal end of the proximal tapered portion of the inner balloon 40 is distal to the distal end of the proximal tapered portion of the outer balloon 50, the distal tapered portion of the inner balloon 40 does not overlap with the distal tapered portion of the outer balloon 50, and the proximal tapered portion of the inner balloon 40 does not overlap with the proximal tapered portion of the outer balloon 50. Therefore, the outer diameter of the balloon group 11 is less likely to increase when the balloon group 11 is in an expanded state, which makes it easier to improve minimal invasiveness.

[0040] The distance from the distal end 40d of the inner balloon 40 to the distal end 50d of the outer balloon 50 in the longitudinal direction x is preferably approximately the same as the distance from the proximal end 40p of the inner balloon 40 to the proximal end 50p of the outer balloon 50 in the longitudinal direction x. In other words, the distance from the distal end 40d of the inner balloon 40 to the distal end 50d of the outer balloon 50 in the longitudinal direction x is preferably 90% or more and 110% or less of the distance from the proximal end 40p of the inner balloon 40 to the proximal end 50p of the outer balloon 50 in the longitudinal direction x. By making the distance from the distal end 40d of the inner balloon 40 to the distal end 50d of the outer balloon 50 approximately the same as the distance from the proximal end 40p of the inner balloon 40 to the proximal end 50p of the outer balloon 50, the inner balloon 40 is more likely to be positioned in the central portion of the balloon group 11 in the longitudinal direction x. As a result, the portion to which the load is applied by the expansion of the balloon group 11 is more likely to be the center of the balloon group 11, and it becomes easier to adjust the location to which pressure is applied by the balloon group 11.

[0041] The position of the midpoint of the length L40 in the longitudinal direction x from the distal end 40d of the inner balloon 40 to the proximal end 40p of the inner balloon 40 preferably coincides with the position of the midpoint of the length L50 in the longitudinal direction x from the distal end 50d of the outer balloon 50 constituting the balloon group 11 to the proximal end 50p of the outer balloon 50. By having the position of the midpoint of the length L40 of the inner balloon 40 coincide with the position of the midpoint of the length L50 of the outer balloon 50 constituting the balloon group 11 in the longitudinal direction x, the balloon 10 is likely to expand most greatly at the midpoint of the length of the balloon group 11 in the longitudinal direction x, making it easier for the balloon group 11 to apply high pressure to the target site.

[0042] 4 and 5 , the outer balloon 50 preferably has a first fold portion 21, a second fold portion 22, and a non-fold portion 30. That is, when the balloon group 11 is deflated, the outer balloon 50 is preferably folded in two so as to extend in the circumferential direction z. By having the outer balloon 50 have the first fold portion 21, the second fold portion 22, and the non-fold portion 30, when the balloons 10 constituting the balloon group 11 are deflated, the outer balloon 50 constituting the outer peripheral portion of the balloon group 11 is more likely to be folded small, making it possible to reduce the outer diameter of the portion where the balloon group 11 is present.

[0043] It is preferable that the outer balloon 50 has only the first fold 21 and the second fold 22 as the fold portions 20, and does not have any other fold portions 20 different from the first fold portion 21 and the second fold portion 22. In other words, it is preferable that the outer balloon 50 has the first fold portion 21, the second fold portion 22, and the non-fold portion 30, and that no other fold portions 20 exist between the first fold portion 21 and the second fold portion 22 in the circumferential direction z. Because the outer balloon 50 does not have any other fold portions 20 different from the first fold portion 21 and the second fold portion 22, when the balloon group 11 is in a deflated state, the outer balloon 50 is easily folded in two along the circumferential direction z, which makes it easier to reduce the outer diameter of the balloon catheter 1 at the portion where the balloon group 11 is located.

[0044] When the balloon group 11 is in a deflated state, the inner balloon 40 has folds 20, and the number of folds 20 that the inner balloon 40 has is preferably greater than the number of folds 20 that the outer balloon 50 has. In other words, when the balloon group 11 is in a deflated state, the inner balloon 40 and the outer balloon 50 have different folded shapes, and it is preferable that the number of folds 20 in the folded shape of the inner balloon 40 is greater than the number of folds 20 in the folded shape of the outer balloon 50. Specifically, for example, in the embodiment shown in Fig. 4, the folded shape of the inner balloon 40 is S-shaped and has four folds 20, and the outer balloon 50 has two folds 20, a first fold 21 and a second fold 22. In the embodiment shown in FIG. 5 , the folded shape of the inner balloon 40 has three wing-shaped portions 60 and three folds 20, while the outer balloon 50 has two folds 20, a first fold 21 and a second fold 22. Details of the wing-shaped portions 60 will be described later. When the balloon group 11 is in a deflated state, the number of folds 20 in the inner balloon 40 is greater than the number of folds 20 in the outer balloon 50. This makes it easier to fold the inner balloon 40 so that its outer diameter is reduced when the balloon group 11 is deflated, and also makes it easier to fold the outer balloon 50 so that it fits the outer periphery of the folded inner balloon 40. As a result, the outer diameter of the portion where the balloon group 11 is located can be easily reduced, thereby further reducing the invasiveness of the balloon catheter 1.

[0045] As shown in FIG. 5 , when the inner balloon 40 is in a deflated state, the inner balloon 40 preferably has a wing-shaped portion 60. The wing-shaped portion 60 refers to the portion of the balloon 10 that is folded over and overlapped with the inner surface facing inward to form a wing shape when the balloon 10 is in a deflated state. The apex 61 of the wing-shaped portion 60 is the fold portion 20. By having the wing-shaped portion 60 when the inner balloon 40 is in a deflated state, the inner balloon 40 can be easily folded to reduce its outer diameter when the balloon group 11 is in a deflated state, and the deflated outer balloon 50 can be easily positioned along the outer periphery of the deflated inner balloon 40. Therefore, when the balloon group 11 is in a deflated state, the outer diameter of the portion of the balloon catheter 1 where the balloon group 11 is located can be reduced, thereby reducing invasiveness.

[0046] In the deflated state of the inner balloon 40, the inner balloon 40 preferably has a plurality of wing-shaped portions 60. Since the inner balloon 40 has a plurality of wing-shaped portions 60 in the deflated state, when the deflated inner balloon 40 is folded, the wing-shaped portions 60 are each wound in the same direction in the circumferential direction z, making it easier to fold the deflated inner balloon 40 so that the outer diameter becomes smaller.

[0047] As shown in Figures 4 and 5, the balloon group 11 includes a first outer balloon 51 and a second outer balloon 52 adjacent to the first outer balloon 51 on one side of the inner balloon 40 in the circumferential direction z. The first outer balloon 51 and the second outer balloon 52 each have a first fold portion 21, a second fold portion 22, and a non-fold portion 30. When the balloon group 11 is in a contracted state, it is preferable that the second fold portion 22 of the first outer balloon 51 is located radially inward of the inner balloon 40 relative to the first fold portion 21 of the second outer balloon 52, and on one side of the inner balloon 40 in the circumferential direction z relative to the first fold portion 21 of the second outer balloon 52. In other words, when the balloon group 11 is in a contracted state, the portion where the second fold portion 22 of the first outer balloon 51 is located and the portion where the first fold portion 21 of the second outer balloon 52 is located overlap each other, and it is preferable that the second fold portion 22 of the first outer balloon 51 is located radially inward in the y direction relative to the first fold portion 21 of the second outer balloon 52.

[0048] When the balloon group 11 is in a deflated state, the second fold 22 of the first outer balloon 51 is located radially inward of the inner balloon 40 relative to the first fold 21 of the second outer balloon 52 and to one side of the inner balloon 40 in the circumferential direction z relative to the first fold 21 of the second outer balloon 52. This allows the first outer balloon 51 and the second outer balloon 52 to be folded and rolled up so that they overlap each other when the balloon group 11 is deflated. This makes it easier to fold the balloon group 11 so that the outer diameter of the balloon catheter 1 is reduced in the area where the balloon group 11 is located. This also has the effect of making it easier to evenly dispose the first outer balloon 51 and the second outer balloon 52 when the balloon group 11 is inflated.

[0049] As shown in FIG. 6 , the balloon group 11 includes a first outer balloon 51, a second outer balloon 52 adjacent to the first outer balloon 51 on one side of the inner balloon 40 in the circumferential direction z, and a third outer balloon 53 adjacent to the first outer balloon 51 on the other side of the inner balloon 40 opposite to the one side in the circumferential direction z. The first outer balloon 51, the second outer balloon 52, and the third outer balloon 53 each have a first folded portion 21, a second folded portion 22, and a non-folded portion 30. In this state, the second fold portion 22 of the first outer balloon 51 is located radially inward of the inner balloon 40 from the first fold portion 21 of the second outer balloon 52 and on one side of the inner balloon 40 in the circumferential direction z from the first fold portion 21 of the second outer balloon 52, and the first fold portion 21 of the first outer balloon 51 may be located radially inward of the inner balloon 40 from the second fold portion 22 of the third outer balloon 53 and on the other side of the inner balloon 40 in the circumferential direction z from the second fold portion 22 of the third outer balloon 53. In other words, when the balloon group 11 is in a contracted state, the portion of the first outer balloon 51 where the second fold portion 22 is located and the portion of the second outer balloon 52 where the first fold portion 21 is located overlap each other, and the portion of the first outer balloon 51 where the first fold portion 21 is located and the portion of the third outer balloon 53 where the second fold portion 22 is located overlap each other, and the first outer balloon 51 may be positioned radially inward of the inner balloon 40 in the y direction relative to the second outer balloon 52 and the third outer balloon 53.

[0050] Furthermore, as shown in Figure 7, when the balloon group 11 is in a contracted state, each outer balloon 50 has a first fold portion 21, a second fold portion 22, and a non-fold portion 30, and the first fold portion 21 and the second fold portion 22 of each outer balloon 50 adjacent in the circumferential direction z may be randomly arranged with no regularity in the positional relationship in the radial direction y.

[0051] 3 , when the balloon group 11 is inflated, the first outer balloon 51 and the second outer balloon 52 are preferably in contact with each other. That is, when the balloon group 11 is inflated, the outer surfaces of at least one pair of adjacent outer balloons 50 are preferably in contact with each other. Because the first outer balloon 51 and the second outer balloon 52 are in contact with each other when the balloon group 11 is inflated, when a fluid is introduced into the balloons 10 constituting the balloon group 11 to inflate the balloons 10, the adjacent first outer balloon 51 and second outer balloon 52 mutually suppress the expansion of each other. As a result, the pressure of the fluid introduced into the lumen of the first outer balloon 51 and the second outer balloon 52 increases, and the hardness of both the first outer balloon 51 and the second outer balloon 52 increases, thereby increasing the expansion force of the balloon group 11.

[0052] When the balloon group 11 is in an expanded state, all of the outer balloons 50 constituting the balloon group 11 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. When the balloon group 11 is in an expanded state, all of the outer balloons 50 constituting the balloon group 11 are in contact with adjacent outer balloons 50. As a result, when the balloon group 11 is expanded, all of the outer balloons 50 constituting the balloon group 11 suppress each other's expansion, and the internal pressure of all of the outer balloons 50 increases. This increases the hardness of the balloon group 11 as a whole, further increasing the expansion force of the balloon group 11.

[0053] As shown in FIG. 3 , when the balloon group 11 is in an expanded state, the outer balloon 50 of the balloon group 11 preferably contacts the outer peripheral surface of the inner balloon 40. That is, when the balloon group 11 is in an expanded state, at least one of the outer balloons 50 of the balloon group 11 preferably contacts the outer surface of the inner balloon 40. When the balloon group 11 is in an expanded state, the outer balloon 50 of the balloon group 11 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 when the balloon group 11 is in an expanded state. 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 expansion force of the balloon group 11. 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 place the balloon group 11 in a high-pressure state.

[0054] It is more preferable that, when the balloon group 11 is in an expanded state, all of the outer balloons 50 constituting the balloon group 11 are in contact with the outer peripheral surface of the inner balloon 40. When the balloon group 11 is in an expanded state, all of the outer balloons 50 constituting the balloon group 11 are in contact with the outer peripheral surface of the inner balloon 40, which tends to enhance 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 group 11.

[0055] 1, 2, and 4 to 7, the balloon catheter 1 preferably further includes a shaft 70 having a longitudinal direction. The distal portion of the shaft 70 is connected to the balloon 10, and a fluid for inflating and deflating the balloon 10 is preferably introduced and discharged through the lumen of the shaft 70.

[0056] The shaft 70 is preferably made of resin, metal, or a combination of resin and metal. Using a resin as the material for the shaft 70 facilitates imparting flexibility and elasticity to the shaft 70. Furthermore, using a metal as the material for the shaft 70 can improve the deliverability of the balloon catheter 1. Examples of resins that can be used to form 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 to form 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.

[0057] 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 further composed of multiple tubular members.

[0058] 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.

[0059] It is preferable that the shaft 70 has a fluid flow path and a guidewire insertion path therein. To configure the shaft 70 to have a fluid flow path and a guidewire insertion path therein, for example, a guidewire tube 192 disposed inside the shaft 70 can function as the guidewire insertion path, and the space between the shaft 70 and the guidewire tube 192 can 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.

[0060] 4 and 5 , in a cross section of the balloon group 11 perpendicular to the longitudinal direction x when the balloon group 11 is in a deflated state, the shortest distance L1 between the centroid P1 of the shaft 70 and the first fold 21 of the outer balloon 50 is preferably greater than the shortest distance L2 between the centroid P1 of the shaft 70 and the second fold 22 of the outer balloon 50. In the deflated state of the balloon group 11, the shortest distance L1 between the centroid P1 of the shaft 70 and the first fold 21 of the outer balloon 50 is greater than the shortest distance L2 between the centroid P1 of the shaft 70 and the second fold 22 of the outer balloon 50. As a result, the first fold 21, which is one end of the outer balloon 50 in the circumferential direction z, is located inward in the radial direction y of the outer balloon 50 adjacent to it, and the second fold 22, which is the other end of the outer balloon 50 in the circumferential direction z, is located outward in the radial direction y of the outer balloon 50 adjacent to it. As a result, when the balloon group 11 is deflated, the outer balloons 50 are rolled up so that they overlap each other, making it easier to fold them so that the outer diameter becomes smaller. Furthermore, when the balloon group 11 is expanded, it becomes easier to evenly arrange the outer balloons 50.

[0061] In a cross section of the balloon group 11 perpendicular to the longitudinal direction x when the balloon group 11 is in a deflated state, the shortest distance L1 between the centroid P1 of the shaft 70 and the first fold 21 of the outer balloon 50 is preferably at least 1.02 times, more preferably at least 1.05 times, and even more preferably at least 1.10 times the shortest distance L2 between the centroid P1 of the shaft 70 and the second fold 22 of the outer balloon 50. By setting the lower limit of the ratio of the shortest distance L1 between the centroid P1 of the shaft 70 and the first fold 21 of the outer balloon 50 to the shortest distance L2 between the centroid P1 of the shaft 70 and the second fold 22 of the outer balloon 50 within the above range, when the balloon group 11 is deflated, the multiple outer balloons 50 can be easily folded so as to overlap and roll up into one another and reduce the outer diameter. Furthermore, in a cross section of the balloon group 11 perpendicular to the longitudinal direction x when the balloon group 11 is in a deflated state, the shortest distance L1 between the centroid P1 of the shaft 70 and the first fold 21 of the outer balloon 50 is preferably 2.0 times or less, more preferably 1.9 times or less, and even more preferably 1.8 times or less, the shortest distance L2 between the centroid P1 of the shaft 70 and the second fold 22 of the outer balloon 50. By setting the upper limit of the ratio of the shortest distance L1 between the centroid P1 of the shaft 70 and the first fold 21 of the outer balloon 50 to the shortest distance L2 between the centroid P1 of the shaft 70 and the second fold 22 of the outer balloon 50 within the above range, the outer diameter of the balloon catheter 1 in a deflated state at the portion where the balloon group 11 is located can be easily reduced.

[0062] As shown in FIGS. 4 to 7 , when the balloon group 11 is in a deflated state, the non-folding portion 30 preferably has a curved portion 80. The curved portion 80 may be formed in the non-folding portion 30 of the outer balloon 50 or in the non-folding portion 30 of the inner balloon 40. The curved portion 80 may be formed by the entire non-folding portion 30 being curved, or by a portion of the non-folding portion 30 being curved. When the balloon group 11 is in a deflated state, the non-folding portion 30 having the curved portion 80 allows the balloons 10 constituting the balloon group 11 to be easily folded and wrapped around the outer periphery of the shaft 70 when the balloon group 11 is deflated. This makes it easier to reduce the outer diameter of the balloon catheter 1 in the area where the balloon group 11 is located.

[0063] 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, the guidewire tube 192 preferably being 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 a guidewire into the balloon catheter 1, and the balloon catheter 1 can be transported into the body along the guidewire. Furthermore, inserting the guidewire into the guidewire tube 192 prevents the guidewire from damaging the balloon 10, etc.

[0064] 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), aromatic polyetherketone resins (e.g., PEEK, etc.), polyetherpolyamide resins, polyurethane resins, polyimide resins, fluorine-based 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 can improve the strength of the guidewire tube 192, its lubricity relative to the guidewire, and its kink resistance.

[0065] 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 minimally invasive properties.

[0066] 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 end of the balloon 10 and the shaft 70 and crimping the end. Of these, it is preferable that the balloon 10 and the shaft 70 be 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.

[0067] 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.

[0068] As shown in Figures 1 and 2, a radiopaque marker 194 may be placed on the guidewire tube 192 inside the balloon 10 at the portion where the balloon 10 is located in the longitudinal direction x so that the position of the balloon 10 can be confirmed under X-ray fluoroscopy.

[0069] The position on the guidewire tube 192 where the radiopaque marker 194 is located may be, 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 proximal and distal ends of the straight tube portion of the inner balloon 40, or the proximal and distal ends of the straight tube portion of the outer balloon 50. In particular, the position on the guidewire tube 192 where the radiopaque marker 194 is located is preferably the proximal and distal ends of the straight tube portion of the inner balloon 40. By locating the radiopaque marker 194 on the guidewire tube 192 at the proximal and distal ends of the straight tube portion of the inner balloon 40, it becomes easier to confirm the position where the balloon group 11 is greatly expanded by the inner balloon 40. As a result, the balloon catheter 1 can be configured to easily apply pressure to the target location.

[0070] 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 portion 6 that communicates with a flow path for fluid supplied to the interior of the balloon 10.

[0071] 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.

[0072] When the balloon catheter 1 is of 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 of an over-the-wire type, a coating may be applied to the outer wall of the outer shaft.

[0073] 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 coating agent or a hydrophobic coating agent, applying a hydrophilic coating agent or a hydrophobic coating agent to the outer wall of the shaft 70, covering the outer wall of the shaft 70 with a hydrophilic coating agent or a hydrophobic coating agent, etc. The coating agent may contain drugs, additives, etc.

[0074] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, methyl vinyl ether maleic anhydride copolymer, and hydrophilic coating agents made from any combination thereof.

[0075] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), silicone oil, hydrophobic urethane resin, carbon coat, diamond coat, diamond-like carbon (DLC) coat, ceramic coat, and substances terminated with alkyl groups or perfluoroalkyl groups and having low surface free energy.

[0076] 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 for dilating a hardened aortic valve and deforming or destroying a biological valve, which cannot be sufficiently dilated with conventional balloon catheters, because it is easy to apply high pressure to the portion where the inner balloon 40 is located.

[0077] This application claims the benefit of priority based on Japanese Patent Application No. 2024-043134, filed on March 19, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-043134, filed on March 19, 2024, are incorporated herein by reference.

[0078] 1: Balloon catheter 5: Hub 6: Fluid injection section 10: Balloon 11: Balloon group 20: Folded section 21: First folded section 22: Second folded section 30: Non-folded section 40: Inner balloon 40d: Distal end of inner balloon 40p: Proximal end of inner balloon 50: Outer balloon 50d: Distal end of outer balloon 50p: Proximal end of outer balloon 51: First outer balloon 52: Second outer balloon 53: Third outer balloon 60: Wing-shaped section 61: Apex of wing-shaped section 70: Shaft 75: Distal shaft 76: Proximal shaft 80: Curved section 93: Guidewire lumen 191: Guidewire port 192: Guidewire tube 193: Distal tip member 194: Radiopaque marker P1: Centroid of shaft L1: Shortest distance between the centroid P1 and the first fold of the outer balloon L2: Shortest distance between the centroid P1 and the second fold of the outer balloon L40: Length of the inner balloon L50: Length of the outer balloon

Claims

1. A balloon catheter having a balloon group including a plurality of balloons arranged in parallel with one another in the circumferential direction, wherein, when the balloon group is in a deflated state, the balloons have two circumferential folds, a first fold and a second fold, and a non-folded portion excluding the first fold, the first fold being located at one circumferential end of the balloon, and the second fold being located at the other circumferential end of the balloon.

2. The balloon catheter according to claim 1, wherein the balloon group includes an inner balloon and a plurality of outer balloons arranged radially outward of the inner balloon, and the outer balloons have the first folded portion, the second folded portion, and the non-folded portion.

3. The balloon catheter according to claim 2, wherein when the balloon group is in a deflated state, the inner balloon has the folds, and the number of folds in the inner balloon is greater than the number of folds in the outer balloon.

4. The balloon catheter according to claim 2, wherein the inner balloon has a wing-shaped portion that is wing-shaped when the inner balloon is in a deflated state.

5. A balloon catheter according to claim 2, wherein the balloon group includes a first outer balloon and a second outer balloon adjacent to the first outer balloon on one circumferential side of the inner balloon, the first outer balloon and the second outer balloon each having the first fold portion, the second fold portion, and the non-fold portion, and when the balloon group is in a deflated state, the second fold portion of the first outer balloon is located radially inward of the inner balloon relative to the first fold portion of the second outer balloon and on one circumferential side of the inner balloon relative to the first fold portion of the second outer balloon.

6. A balloon catheter as described in claim 2, further comprising a shaft having a longitudinal direction, wherein in a cross section of the balloon group perpendicular to the longitudinal direction when the balloon group is in a contracted state, the shortest distance between the centroid of the shaft and the first fold of the outer balloon is greater than the shortest distance between the centroid of the shaft and the second fold of the outer balloon.

7. The balloon catheter according to claim 1, wherein the non-folded portion has a curved portion when the balloon group is in a deflated state.

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