Balloon catheter

Abstract

The present invention provides a balloon catheter capable of widely changing the outer diameter of a balloon in an expanded state according to the level of pressure applied to the balloon, wherein the balloon catheter can be used for various lesions or the like.　This balloon catheter includes a shaft that extends in the longitudinal direction from the proximal side to the distal side of the shaft, and a balloon group that is disposed at the distal part of the shaft and includes a plurality of balloons. The balloon group has a first expanded state in which the balloon group is pressurized by a first pressure, and a second expanded state in which the balloon group is pressurized by a second pressure higher than the first pressure. The diameter D1 of a first shortest circumscribed circle of the balloon group at a midpoint in the longitudinal direction of the balloon group in the first expanded state satisfies a predetermined requirement 1, and the diameter D2 of a second shortest circumscribed circle of the balloon group at the midpoint in the second expanded state satisfies a predetermined requirement 2.

Description

Balloon catheter

[0001] This disclosure relates to balloon catheters.

[0002] Angina pectoris and myocardial infarction are caused by the formation of narrowed areas in the inner walls of blood vessels due to hardening caused by calcification, etc. One treatment method for these conditions is angioplasty, which uses a balloon catheter to dilate the narrowed area. Angioplasty is sometimes called percutaneous transluminal angioplasty (PTA) or percutaneous transluminal coronary angioplasty (PTCA). Angioplasty is a minimally invasive treatment that does not require open-heart surgery like bypass surgery, and is widely performed.

[0003] A balloon catheter used in angioplasty has a shaft that extends longitudinally from the proximal to the distal end, and a balloon positioned at the distal end of the shaft. An example of such a balloon catheter is described in Patent Document 1. Figure 42 of Patent Document 1 shows an expansion device comprising an inner balloon member and a plurality of outer balloon members.

[0004] U.S. Patent Application Publication No. 2012 / 0209375

[0005] As described in Patent Document 1, a balloon catheter having an inner balloon positioned at the distal end of the shaft and a balloon group consisting of multiple outer balloons arranged radially outward from the inner balloon and aligned circumferentially to the inner balloon allows for a large increase in the outer diameter of the balloon when it is expanded, thus enabling a large expansion of stenotic areas. However, since the outer diameter of the balloon in its expanded state is determined by the balloon itself, if the stenotic area is significantly narrowed, or conversely, if the stenotic area is not as narrowed as expected and needs to be expanded more than expected, it is necessary to replace the balloon catheter and perform the procedure so that the outer diameter of the balloon in its expanded state is appropriate.

[0006] The problem addressed by this disclosure is to provide a balloon catheter that can be used in various lesions and other areas by widely changing the outer diameter of the balloon in its expanded state by varying the pressure applied to the balloon.

[0007] The present disclosure is as follows: [1] A balloon catheter having a shaft extending longitudinally from proximal to distal, and a balloon group disposed at the distal end of the shaft and composed of a plurality of balloons, wherein the plurality of balloons constituting the balloon group have an inner balloon and N (where N is an integer of 2 or more) outer balloons arranged radially outward of the inner balloon and in a circumferential direction of the inner balloon, the inner balloon and the outer balloons each have a straight section, a proximal tapered section located proximal to the straight section and a distal tapered section located distal to the straight section, the balloon group has a first expanded state in which the balloon group is pressurized by a first pressure and a second expanded state in which the balloon group is pressurized by a second pressure higher than the first pressure, and the diameter D of the first shortest circumscribed circle of the balloon group at the midpoint of the balloon group in the longitudinal direction in the first expanded state １ The following requirement 1 is met, and the diameter D of the second shortest circumscribed circle of the balloon group at the midpoint in the second expanded state is... ２ The balloon catheter satisfies requirement 2 below. (Requirement 1) A first inner virtual circle whose diameter is the outer diameter of the inner balloon at the midpoint when the inner balloon is pressed by the first pressure in a state in which it is alone and not in contact with the other balloons constituting the balloon group, and a first outer virtual circle whose diameter is the outer diameter of the outer balloon at the midpoint when the outer balloon is pressed by the first pressure in a state in which it is alone and not in contact with the other balloons constituting the balloon group, wherein the diameter D of the first shortest circumscribed circle １ The diameter D of the first virtual shortest circumscribed circle of the first virtual balloon group, which is formed by arranging N first outer virtual circles in the circumferential direction of the first inner virtual circle radially outward from the first inner virtual circle. Ｖ１Smaller than (Requirement 2) A second inner virtual circle whose diameter is the outer diameter of the inner balloon at the midpoint when the inner balloon is pressurized by the second pressure in a state in which it is alone and not in contact with the other balloons that make up the balloon group, and a second outer virtual circle whose diameter is the outer diameter of the outer balloon at the midpoint when the outer balloon is pressurized by the second pressure in a state in which it is alone and not in contact with the other balloons that make up the balloon group, wherein the diameter D of the second shortest circumscribed circle ２ The diameter D of the second virtual shortest circumscribed circle of the second virtual balloon group, which is formed by arranging N of the second outer virtual circles in the circumferential direction of the second inner virtual circle radially outward from the second inner virtual circle. Ｖ２[1] The balloon catheter according to [1], wherein the outer diameter of the balloon group at the midpoint in the second expanded state is greater than the outer diameter of the balloon group at the portion where the distal end of the proximal tapered portion of the outer balloon is located, and the outer diameter of the balloon group at the portion where the proximal end of the distal tapered portion of the outer balloon is located. [3] The balloon catheter according to [1] or [2], wherein the longitudinal length of the inner balloon is shorter than the longitudinal length of the outer balloon. [4] The balloon catheter according to any one of [1] to [3], wherein the shaft has a proximal shaft portion located proximal to the inner balloon and a distal shaft portion located distal to the inner balloon, and the inner balloon and the outer balloon each have a proximal sleeve portion located proximal to the proximal tapered portion and a distal sleeve portion located distal to the distal tapered portion, and the proximal sleeve portion of the inner balloon and the proximal sleeve portion of the outer balloon are connected to the proximal shaft portion, and the distal sleeve portion of the inner balloon and the distal sleeve portion of the outer balloon are connected to the distal shaft portion, respectively. [5] The balloon catheter according to any one of [1] to [4], wherein the longitudinal length of the straight tube portion of the inner balloon is shorter than the longitudinal length of the straight tube portion of the outer balloon. [6] The balloon catheter according to any one of [1] to [5], wherein the distal end of the proximal tapered portion of the inner balloon is located distal to the distal end of the proximal tapered portion of the outer balloon, and the proximal end of the distal tapered portion of the inner balloon is located proximal to the proximal end of the distal tapered portion of the outer balloon. [7] The balloon catheter according to any one of [1] to [6], wherein, when the inner balloon and the balloon group are expanded, adjacent outer balloons constituting the balloon group are in contact with each other.[8] A balloon catheter according to any one of [1] to [7], wherein, when the inner balloon and the balloon group are expanded, the maximum outer diameters of all the outer balloons constituting the balloon group are the same, and the maximum outer diameter of the outer balloons is the same as the maximum outer diameter of the inner balloon. [9] A balloon catheter according to any one of [1] to [7], wherein, when the balloon group is expanded, there are two or more outer balloons constituting the balloon group that have different maximum outer diameters.

[10] A balloon catheter according to [9], wherein, when the inner balloon and the balloon group are expanded, two outer balloons with different maximum outer diameters are arranged circumferentially around the outer circumference of the inner balloon, and the outer balloon with the smaller maximum outer diameter is sandwiched between the outer balloons with the larger maximum outer diameter.

[11] A balloon catheter according to any one of [1] to [7], wherein, when the inner balloon and the balloon group are expanded, the maximum outer diameters of all the outer balloons constituting the balloon group are the same, and the maximum outer diameter of the outer balloons is different from the maximum outer diameter of the inner balloon.

[12] The balloon catheter according to

[11] , wherein the maximum outer diameter of the outer balloon constituting the balloon group is smaller than the maximum outer diameter of the inner balloon.

[0008] According to this disclosure, the outer diameter of the balloon in its expanded state can be widely changed by varying the pressure applied to the balloon, and a balloon catheter can be provided that can be used for various lesions and other areas.

[0009] Figure 1 is a side view (partially a fluoroscopic view) of a balloon catheter. Figure 2 is a magnified side view of the balloon shown in Figure 1. Figure 3 is a cross-sectional view of the balloon shown in Figure 1 at the III-III line position. Figure 4 is a side view of Figure 2, with the outer balloon located on the near side omitted for ease of explanation. Figure 5 is a cross-sectional view of the inner balloon shown in Figure 3, shown alone. Figure 6 is a cross-sectional view of the outer balloon constituting the outer balloon B shown in Figure 3, shown alone. Figure 7 is a schematic diagram showing a first virtual balloon group (second virtual balloon group) in which six first outer virtual circles Vb1 (second outer virtual circle Vb2) are arranged radially outward from the first inner virtual circle Va1 (second inner virtual circle Va2) in the circumferential direction of the first inner virtual circle Va1 (second inner virtual circle Va2). Figure 8 is a side view of the balloon shown in Figures 1 and 2 in its second expanded state. Figure 9 is a cross-sectional view of a balloon different from the balloons shown in Figures 1 and 2 at the III-III line position. Figure 10 is a cross-sectional view of a balloon at the III-III line position, which is different from the balloons shown in Figures 1 and 2.

[0010] The embodiment of the balloon catheter comprises a shaft extending longitudinally from proximal to distal, and a balloon group disposed at the distal end of the shaft and composed of a plurality of balloons, wherein the plurality of balloons constituting the balloon group have an inner balloon and N (where N is an integer of 2 or more) outer balloons arranged radially outward of the inner balloon and aligned in the circumferential direction of the inner balloon, the inner balloon and the outer balloons each have a straight section, a proximal tapered section located proximal to the straight section and a distal tapered section located distal to the straight section, the balloon group has a first expanded state in which the balloon group is pressurized by a first pressure and a second expanded state in which the balloon group is pressurized by a second pressure higher than the first pressure, and the diameter D of the first shortest circumscribed circle of the balloon group at the midpoint of the balloon group in the longitudinal direction in the first expanded state １ The following requirement 1 is met, and the diameter D of the second shortest circumscribed circle of the balloon group at the midpoint in the second expanded state is...２ is characterized in that it satisfies Requirement 2 below. With this feature, the outer diameter of the balloons in an expanded state can be widely varied depending on the level of pressure applied to the balloons, so the size of the outer diameter of the balloons in the expanded state can be adjusted by controlling the pressure applied to the balloons. As a result, the outer diameter of the balloons in the expanded state can be appropriately adjusted according to the stenosis state of a lesion or the like, which eliminates the need to replace a balloon catheter, allows the procedure to proceed promptly, and can reduce the burden on a patient. (Requirement 1) In a state where the inner balloon is pressurized by the first pressure in a state where it is alone and not in contact with the other balloons constituting the balloon group, a first inner imaginary circle whose diameter is the outer diameter of the inner balloon at a portion located at the midpoint; and in a state where the outer balloon is pressurized by the first pressure in a state where it is alone and not in contact with the other balloons constituting the balloon group, a first outer imaginary circle whose diameter is the outer diameter of the outer balloon at a portion located at the midpoint, the diameter D of the first minimum circumscribed circle １ of a first imaginary balloon group in which N of said first outer imaginary circles are arranged side by side in the circumferential direction of said first inner imaginary circle radially outward of said first inner imaginary circle, the diameter D Ｖ１ is smaller than . (Requirement 2) In a state where the inner balloon is pressurized by the second pressure in a state where it is alone and not in contact with the other balloons constituting the balloon group, a second inner imaginary circle whose diameter is the outer diameter of the inner balloon at a portion located at the midpoint; and in a state where the outer balloon is pressurized by the second pressure in a state where it is alone and not in contact with the other balloons constituting the balloon group, a second outer imaginary circle whose diameter is the outer diameter of the outer balloon at a portion located at the midpoint, the diameter D of the second minimum circumscribed circle ２ of a second imaginary balloon group in which N of said second outer imaginary circles are arranged side by side in the circumferential direction of said second inner imaginary circle radially outward of said second inner imaginary circle, the diameter D Ｖ２ is larger than .

[0011] The balloon catheter will be described in detail below with reference to the drawings, but the contents of this disclosure are not limited to the illustrated examples, and modifications can be made to the extent that they are in line with the spirit described above and below, and all such modifications are included in the technical scope of this disclosure. In each drawing, hatching and reference numerals may be omitted for convenience, in which case refer to the specification or other drawings. Also, the dimensions of various parts in the drawings may differ from the actual dimensions, as priority is given to helping to understand the features of this disclosure.

[0012] Figure 1 is a side view (partially a fluoroscopic view) showing an embodiment of a balloon catheter. Hereafter, the same components will be denoted by the same reference numerals to avoid redundant explanations. Figure 2 is a magnified side view of the balloon shown in Figure 1. Figure 3 is a cross-sectional view of the balloon shown in Figure 1 at the line III-III. Figure 4 is a side view of Figure 2, with the outer balloon located on the near side omitted for ease of explanation. Figure 4 shows the inner balloon A and the outer balloons b1 and b4. In Figures 1, 2, and 4, the left side of the figure is the proximal side (operator side), and the right side is the distal side (affected area side).

[0013] The balloon catheter 1 has a shaft 10 that extends longitudinally x from the proximal to the distal end. A balloon group 2, consisting of multiple balloons, is arranged at the distal end of the shaft 10. The balloons constituting the balloon group 2 consist of an inner balloon A and N outer balloons B (where N is an integer of 2 or more) arranged radially outward from the inner balloon A and aligned in the circumferential direction of the inner balloon A. Figures 1 to 3 show a state in which the outer balloons b1 to b4, etc. are arranged radially outward from the inner balloon A, and the outer balloons b1 to b4, etc. are arranged in the circumferential direction z of the inner balloon A. In this specification, the multiple outer balloons b1 to b4, etc. may be collectively referred to as "outer balloon B".

[0014] The shaft 10 has a longitudinal direction x, a radial direction y connecting the centroid of the outer edge of the shaft 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 shaft 10 in a cross section perpendicular to the longitudinal direction x. In this specification, the direction toward the user's hand in the longitudinal direction x is referred to as the proximal side, and the direction opposite to the proximal side, i.e., toward the person being treated, is referred to as the distal side. Other members and parts 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 shaft 10. However, for ease of understanding, in this specification, all members and parts are described as having the same longitudinal direction x, radial direction y, and circumferential direction z as the shaft 10.

[0015] As shown in Figures 2 and 4, the inner balloon A has a straight tube section 23, a proximal tapered section 22 located proximal to the straight tube section 23, and a distal tapered section 24 located distal to the straight tube section 23. As shown in Figures 2 and 4, the inner balloon A may also have a proximal sleeve section 21 located proximal to the proximal tapered section 22 and a distal sleeve section 25 located distal to the distal tapered section 24. As shown in Figures 2 and 4, the outer balloon B each has a straight tube section 23, a proximal tapered section 22 located proximal to the straight tube section 23, and a distal tapered section 24 located distal to the straight tube section 23. As shown in Figures 2 and 4, the outer balloon B each may also have a proximal sleeve section 21 located proximal to the proximal tapered section 22 and a distal sleeve section 25 located distal to the distal tapered section 24.

[0016] The balloon group 2 of the balloon catheter 1 has a first expansion state in which the balloon group 2 is pressurized by a first pressure, and a second expansion state in which the balloon group 2 is pressurized by a second pressure higher than the first pressure. In the balloon group 2 of the balloon catheter 1, the shortest circumscribed circle of the balloon group 2 at the midpoint G in the longitudinal direction x of the balloon group 2 in the first expansion state is defined as the first shortest circumscribed circle V1, and the diameter of this first shortest circumscribed circle V1 is defined as D. １ In this case, the diameter D of the first shortest circumscribed circle V1 is １The above requirement 1 is satisfied. Furthermore, the shortest circumscribed circle of balloon group 2 at the midpoint G in the longitudinal direction x of balloon group 2 in the second expanded state is defined as the second shortest circumscribed circle V2, and the diameter of this second shortest circumscribed circle V2 is defined as D. ２ In this case, the diameter D of the second shortest circumscribed circle V2 is ２ This satisfies requirement 2 above.

[0017] Requirements 1 and 2 will be explained using Figures 3, 5-7. Note that Requirement 1 specifies the case where the pressure used to expand balloon group 2 is the first pressure, and Requirement 2 specifies the case where the pressure used to expand balloon group 2 is the second pressure. Although the pressures specified for Requirement 1 and Requirement 2 are different, the same diagram will be used for explanation purposes.

[0018] Figure 5 is a cross-sectional view of the inner balloon A shown in Figure 3, showing it alone and indicating that the inner balloon A is not in contact with the other balloons that make up balloon group 2. The dotted line Va1 indicates a virtual circle (first inner virtual circle) in the inner balloon A shown in Figure 5, with its diameter equal to the outer diameter when pressurized by the first pressure. The dotted line Va2 indicates a virtual circle (second inner virtual circle) in the inner balloon A shown in Figure 5, with its diameter equal to the outer diameter when pressurized by the second pressure.

[0019] Figure 6 is a cross-sectional view of outer balloon b1, which constitutes outer balloon B as shown in Figure 3, showing the state in which outer balloon b1 is not in contact with the other balloons that make up balloon group 2. Vb1 is a virtual circle (first outer virtual circle) in outer balloon b1 shown in Figure 6, with the outer diameter as its diameter when pressurized by the first pressure. Vb2 is a virtual circle (second outer virtual circle) in outer balloon b1 shown in Figure 6, with the outer diameter as its diameter when pressurized by the second pressure.

[0020] Figure 7 is a schematic diagram showing a first virtual balloon group (second virtual balloon group) in which six first outer virtual circles Vb1 (second outer virtual circle Vb2) are arranged radially outward from the first inner virtual circle Va1 (second inner virtual circle Va2) in the circumferential direction of the first inner virtual circle Va1 (second inner virtual circle Va2). The shortest circumscribed circle of the first virtual balloon group shown in Figure 7 is the first virtual shortest circumscribed circle V ｖ１ Let the shortest circumscribed circle of the second virtual balloon group be the second virtual shortest circumscribed circle V. ｖ２ Let's define the shortest circumscribed circle as the circle that contains all the other circles and has the smallest radius.

[0021] (Requirement 1) When inner balloon A is pressed by the first pressure in a state where it is alone and not in contact with other balloons constituting balloon group 2, the first inner virtual circle Va1 is defined as a virtual circle whose diameter is the outer diameter of inner balloon A at the point located at the midpoint G. When outer balloon B is pressed by the first pressure in a state where it is alone and not in contact with other balloons constituting balloon group 2, the first outer virtual circle Vb1 is defined as a virtual circle whose diameter is the outer diameter of outer balloon B at the point located at the midpoint G. Diameter D of the first shortest circumscribed circle V1 １ This is the first virtual shortest circumscribed circle V of the first virtual balloon group, which is formed by arranging N first outer virtual circles Vb1 in the circumferential direction of the first inner virtual circle Va1 radially outward from the first inner virtual circle Va1. ｖ１ Diameter D Ｖ１ It is smaller than (Requirement 2) When inner balloon A is pressed by the second pressure in a state where it is alone and not in contact with other balloons constituting balloon group 2, the virtual circle with the outer diameter of inner balloon A at the midpoint G is defined as the second inner virtual circle Va2. When outer balloon B is pressed by the second pressure in a state where it is alone and not in contact with other balloons constituting balloon group 2, the virtual circle with the outer diameter of outer balloon B at the midpoint G is defined as the second outer virtual circle Vb2. The diameter D of the second shortest circumscribed circle V2 ２ This is the second virtual shortest circumscribed circle V of the second virtual balloon group, which is formed by arranging N second outer virtual circles Vb2 in the circumferential direction of the second inner virtual circle Va2 radially outward from the second inner virtual circle Va2. ｖ２ Diameter D Ｖ２is larger than that.

[0022] As described above, the diameter D of the first minimum circumscribed circle V1 １ is smaller than the diameter D of the first virtual minimum circumscribed circle V of the first virtual balloon group ｖ１ Ｖ１ , and the diameter D of the second minimum circumscribed circle V2 ２ is larger than the diameter D of the second virtual minimum circumscribed circle V of the second virtual balloon group ｖ２ Ｖ２ Owing to the above feature, the outer diameter of the balloons in an expanded state can be widely changed depending on the level of pressure applied to the balloons, so that the balloon group can be used for various lesions and the like.

[0023] For example, in the second expanded state, assuming that the outer diameter of the inner balloon A at the midpoint G is 8 mm and all outer diameters of the outer balloons B are 8 mm, when the diameter D of the second minimum circumscribed circle ２ is equal to the diameter D of the second virtual minimum circumscribed circle of the second virtual balloon group in which N second outer virtual circles are arranged side by side in the circumferential direction of the second inner virtual circle on the radially outer side of the second inner virtual circle Ｖ２ , as shown in FIG. 4, in the second expanded state, the diameter of the balloon group 2 at the midpoint G is 24 mm.

[0024] On the other hand, according to the embodiment, in the second expanded state, the diameter D of the second minimum circumscribed circle ２ is larger than the diameter D of the second virtual minimum circumscribed circle of the second virtual balloon group in which N second outer virtual circles are arranged side by side in the circumferential direction of the second inner virtual circle on the radially outer side of the second inner virtual circle Ｖ２ . That is, the diameter D of the second minimum circumscribed circle ２ exceeds 24 mm. This will be described with reference to FIG. 8. FIG. 8 is a side view of the balloon shown in FIGS. 1 and 2 in the second expanded state, and similar to FIG. 4, for convenience of explanation, the outer balloon B arranged on the near side is omitted. As shown in FIG. 8, in the second expanded state, the straight pipe portion 23 of the outer balloon B protrudes radially outward and has an arched curved shape, so the outer diameter of the balloon group 2 at the midpoint G exceeds 24 mm and becomes larger. Further, according to the embodiment, in the first expanded state, the diameter D of the first minimum circumscribed circle １is the diameter D of the first virtual shortest circumscribed circle of the first virtual balloon group in which N first outer virtual circles are arranged side by side in the circumferential direction of the first inner virtual circle on the radially outer side of the first inner virtual circle Ｖ１ which is smaller than the above. This means that in the first expanded state, the straight pipe portion 23 of the outer balloon B is flattened, and the outer diameter of the balloon group 2 at the midpoint G is less than 24 mm.

[0025] The balloon group 2 may have a third expanded state in which the balloon group 2 is inflated by a third pressure that is higher than the first pressure and lower than the second pressure. The diameter D3 of the third shortest circumscribed circle of the balloon group 2 at the midpoint G in the longitudinal direction x of the balloon group 2 in the third expanded state may satisfy the following requirement 3. (Requirement 3) A third inner virtual circle whose diameter is the outer diameter of the inner balloon A at the portion located at the midpoint G when the inner balloon A is inflated by the third pressure in a state where the inner balloon A is alone and not in contact with other balloons constituting the balloon group 2; and a third outer virtual circle whose diameter is the outer diameter of the outer balloon B at the portion located at the midpoint G when the outer balloon B is inflated by the third pressure in a state where the outer balloon B is alone and not in contact with other balloons constituting the balloon group 2, wherein D3 is the diameter of the third shortest circumscribed circle, and D is the diameter of the third virtual shortest circumscribed circle of the third virtual balloon group in which N third outer virtual circles are arranged side by side in the circumferential direction of the third inner virtual circle on the radially outer side of the third inner virtual circle Ｖ３ and D3 are the same.

[0026] The difference between the first pressure and the second pressure may be, for example, 4 to 6 atm. The difference between the first pressure and the third pressure may be, for example, 1 to 4 atm. The difference between the second pressure and the third pressure may be, for example, 1 to 4 atm.

[0027] In the second expansion state, the outer diameter of the balloon group 2 at the midpoint G may be larger than the outer diameter of the balloon group 2 at the point where the distal end 22d of the proximal tapered portion 22 of the outer balloon B is located, and the outer diameter of the balloon group 2 at the point where the proximal end 24p of the distal tapered portion 24 of the outer balloon B is located. This makes it easier for the straight tube portion 23 of the balloon to protrude radially outward and take on an arched shape in the second expansion state, making it easier to expand constricted areas, etc. Note that the outer diameter refers to the diameter of the shortest circumscribed circle.

[0028] The outer diameter of the balloon group 2 at the midpoint G in the second expanded state may be 3% or more, preferably 5% or more, more preferably 10% or more, and may be 20% or less greater than the larger of the outer diameter of the balloon group 2 at the portion where the distal end 22d of the proximal tapered portion 22 of the outer balloon B is located, and the outer diameter of the balloon group 2 at the portion where the proximal end 24p of the distal tapered portion 24 of the outer balloon B is located.

[0029] The outer diameter of the balloon group 2 at the midpoint G in the second expansion state may be 20% or more, and may be 30% or less, greater than the larger of the outer diameter of the balloon group 2 at the point where the distal end 22d of the proximal tapered portion 22 of the outer balloon B is located, and the outer diameter of the balloon group 2 at the point where the proximal end 24p of the distal tapered portion 24 of the outer balloon B is located.

[0030] In the balloon group 2 of the balloon catheter 1, the length La of the inner balloon A in the longitudinal direction x may be shorter than the length Lb of the outer balloon B in the longitudinal direction x. This makes it easier for the outer balloon B to curve significantly in an arc shape in the second expansion state, and makes it easier to create a widening of the outer diameter of the balloon depending on the pressure level. The length La of the inner balloon A refers to the length in the longitudinal direction x from the proximal end 22p of the proximal tapered portion 22 of the inner balloon A to the distal end 24d of the distal tapered portion 24. The length Lb of the outer balloon B refers to the length in the longitudinal direction x from the proximal end 22p of the proximal tapered portion 22 of the outer balloon B to the distal end 24d of the distal tapered portion 24.

[0031] The length La of the inner balloon A in the longitudinal direction x may be 5% or more shorter than the length Lb of the outer balloon B in the longitudinal direction x, preferably 10% or more shorter, and more preferably 15% or more shorter. The length La of the inner balloon A in the longitudinal direction x may be 30% or less than the length Lb of the outer balloon B in the longitudinal direction x.

[0032] The shaft 10 may have a proximal shaft portion 10p located proximal to the proximal end 22p of the proximal tapered portion 22 of the inner balloon A, and a distal shaft portion 10d located distal to the distal end 24d of the distal tapered portion 24 of the inner balloon A. The inner balloon A may also have a proximal sleeve portion 21 located proximal to the proximal end 22p of the proximal tapered portion 22, and a distal sleeve portion 25 located distal to the distal end 24d of the distal tapered portion 24. The outer balloon B may also have a proximal sleeve portion 21 located proximal to the proximal end 22p of the proximal tapered portion 22, and a distal sleeve portion 25 located distal to the distal end 24d of the distal tapered portion 24. It is preferable that the proximal sleeve portion 21 of the inner balloon A and the proximal sleeve portion 21 of the outer balloon B are connected to the proximal shaft portion 10p, respectively. It is also preferable that the distal sleeve portion 25 of the inner balloon A and the distal sleeve portion 25 of the outer balloon B are connected to the distal shaft portion 10d, respectively. This makes it easier for the central part of the straight tube portion 23 of the outer balloon B to curve radially outward in the second expansion state, thus making it easier to control the width of the outer diameter of the balloon group 2 depending on the pressure level when pressurizing the balloon group 2.

[0033] In the balloon catheter 1, the length ALe of the straight tube portion 23 of the inner balloon A in the longitudinal direction x may be shorter than the length BLE of the straight tube portion 23 of the outer balloon B in the longitudinal direction x. This makes it easier for the central part of the straight tube portion 23 of the outer balloon B to curve radially outward in the second expansion state, thus making it easier to control the width of the outer diameter of the balloon group 2 by varying the pressure when pressurizing the balloon group 2.

[0034] The length ALe of the straight tube portion 23 of the inner balloon A in the longitudinal direction x is preferably 5% or more shorter than the length BLE of the straight tube portion 23 of the outer balloon B in the longitudinal direction x, more preferably 10% or more shorter, and even more preferably 15% or more shorter. The length ALe of the straight tube portion 23 of the inner balloon A in the longitudinal direction x is preferably 50% or less shorter than the length BLE of the straight tube portion 23 of the outer balloon B in the longitudinal direction x, more preferably 40% or less, and even more preferably 30% or less.

[0035] The length ALe of the straight tube portion 23 of the inner balloon A in the longitudinal direction x may be, for example, 10 to 30 mm, 15 to 25 mm, or 18 to 23 mm. The length BLE of the straight tube portion 23 of the outer balloon B in the longitudinal direction x may be, for example, 30 to 50 mm, 25 to 45 mm, or 28 to 43 mm.

[0036] In the balloon catheter 1, the distal end 22d of the proximal tapered portion 22 of the inner balloon A may be located distal to the distal end 22d of the proximal tapered portion 22 of the outer balloon B, and the proximal end 24p of the distal tapered portion 24 of the inner balloon A may be located proximal to the proximal end 24p of the distal tapered portion 24 of the outer balloon B. This makes it easier for the central part of the straight tube portion 23 of the outer balloon B to curve radially outward in the second expansion state, thus making it easier to control the width of the outer diameter of the balloon group 2 by varying the pressure when pressurizing the balloon group 2.

[0037] As shown in Figures 1 to 3, the balloon catheter 1 has multiple outer balloons B, which are arranged radially outward from the inner balloon A and aligned in the circumferential direction z of the inner balloon A. The arrangement of the inner balloon A and the multiple outer balloons will be explained using Figures 3, 9, and 10. Figure 3 is a cross-sectional view of the balloon group 2 shown in Figures 1 and 2 at the position of line III-III. Figures 9 and 10 are cross-sectional views of the balloon group 2 at the position of line III-III with a different configuration from the balloon group 2 shown in Figures 1 and 2.

[0038] The balloon catheter 1 shown in Figure 3 consists of one inner balloon A and six outer balloons, which together constitute the balloon group 2. In Figure 3, for the sake of explanation, four of the six outer balloons are labeled b1 to b4. When the inner balloon A and outer balloon b1 are expanded, the maximum outer diameter of the inner balloon A is denoted as Da, and the maximum outer diameter of the outer balloons b1 is denoted as Db1 (the same applies hereafter).

[0039] The balloon catheter 1 shown in Figure 9 consists of one inner balloon A and eight outer balloons, which together constitute the balloon group 2. In Figure 9, for the sake of explanation, four of the eight outer balloons are labeled b11 to b14.

[0040] The balloon catheter 1 shown in Figure 10 consists of one inner balloon A and 20 outer balloons, which together constitute the balloon group 2. In Figure 10, for the sake of explanation, three of the 20 outer balloons are labeled b21 to b23.

[0041] As shown in Figure 3, the balloon catheter 1 has multiple outer balloons B radially outward from the inner balloon A and in the circumferential direction z of the inner balloon A. By expanding both the inner balloon A and the multiple outer balloons B, the outer diameter of the balloon group 2 can be increased. As a result, the stenotic portion can be reliably expanded.

[0042] As shown in Figure 3, when the balloon group 2 of the balloon catheter 1 is expanded, it is preferable that adjacent outer balloons b1 and b2 among the multiple outer balloons B constituting the balloon group 2 are in contact with each other. When adjacent outer balloons b1 and b2 are in contact with each other, the outer balloons suppress each other's expansion, thereby increasing pressure resistance and thus increasing the expansion force of the balloon group 2. In addition, when adjacent outer balloons b1 and b2 are in contact with each other, even if the outer balloons come into contact with the stenosis, they are less likely to shift in the circumferential direction z of the outer circumference of the inner balloon A, so that the stenosis can be reliably expanded.

[0043] When balloon group 2 is expanded, it is sufficient for at least one pair of adjacent outer balloons B to be in contact with each other, preferably two or more pairs of adjacent outer balloons B are in contact with each other, and more preferably all adjacent outer balloons B are in contact with each other. When all adjacent outer balloons B are in contact with each other, the outer balloons B can be expanded uniformly.

[0044] During the expansion of balloon group 2, the outer balloon B does not need to be in contact with the outer surface of the inner balloon A.

[0045] The number of outer balloons B 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 B within the above range, it becomes easier to surround the outer circumference of inner balloon A, and outer balloons B can more easily suppress the expansion of inner balloon A. As a result, when fluid is introduced into both balloons of balloon group 2, inner balloon A and outer balloon B suppress each other's expansion, thereby increasing the pressure resistance of balloon group 2, increasing its hardness, and improving its expansion force. Furthermore, because inner balloon A and outer balloon B suppress each other's expansion, balloon group 2 becomes less likely to inflate, so even if high pressure is applied to balloon group 2, over-expansion of balloon group 2 is suppressed, preventing balloon group 2 from expanding beyond the target outer diameter, thereby reducing damage to in vivo lumens such as aortic valves and improving safety. There is no particular upper limit to the number of outer balloons B, but for example, it 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 B within the above range, the outer balloons B become less likely to shift radially (y) and circumferentially (z) relative to the inner balloon A, making it easier to suppress the expansion of the inner balloon A by the outer balloons B.

[0046] When balloon group 2 is expanded, the maximum outer diameter of the circumscribed circle of balloon group 2 is not particularly limited, but for example, a range of 5 mm to 60 mm is preferred.

[0047] The relationship between the maximum outer diameter of inner balloon A and the maximum outer diameter of outer balloon B is preferably one of the following (1) to (3): (1) When balloon group 2 is expanded, all outer balloons B included in balloon group 2 have the same maximum outer diameter, and the size of the maximum outer diameter of outer balloon B is the same as the size of the maximum outer diameter of inner balloon A included in balloon group 2. (2) When balloon group 2 is expanded, there are two or more types of outer balloons B included in balloon group 2 with different maximum outer diameters. (3) When balloon group 2 is expanded, all outer balloons B included in balloon group 2 have the same maximum outer diameter, and the size of the maximum outer diameter of outer balloon B is different from the size of the maximum outer diameter of inner balloon A included in balloon group 2.

[0048] The maximum outer diameter of inner balloon A refers to the maximum circular diameter of inner balloon A in a cross-section perpendicular to the longitudinal direction x of inner balloon A. The maximum outer diameter of outer balloon B refers to the maximum circular diameter of outer balloon B in a cross-section perpendicular to the longitudinal direction x of outer balloon B.

[0049] (1) will be explained using Figure 3. As shown in Figure 3, when the balloon group 2 is expanded, the maximum outer diameter of all the outer balloons B is the same, and the maximum outer diameter of the outer balloons B is the same as the maximum outer diameter of the inner balloon A. This makes it easier to balance the force that the inner balloon A tries to expand with the force that the outer balloons B exert to suppress the expansion of the inner balloon A. As a result, the hardness of the inner balloon A and the balloon group 2 increases, making it easier to increase the expansion force of the balloon group 2 and allowing the constricted area to be expanded uniformly.

[0050] When the maximum outer diameter of inner balloon A and all outer balloons B are the same, the maximum outer diameter of inner balloon A and outer balloons B is preferably, for example, 3 mm to 8 mm. When the maximum outer diameters of multiple outer balloons B are all the same, it means that the maximum outer diameters of multiple outer balloons B are approximately the same, specifically that the maximum outer diameter of the outer balloon B with the largest maximum outer diameter is 100% to 110% of the maximum outer diameter of the outer balloon B with the smallest maximum outer diameter. When the maximum outer diameter of inner balloon A is the same as the maximum outer diameter of multiple outer balloons B, it means that the maximum outer diameter of inner balloon A and the maximum outer diameters of multiple outer balloons B are approximately the same, specifically that the maximum outer diameter of inner balloon A is 90% to 110% of the maximum outer diameter (for example, the average value) of outer balloons B.

[0051] (2) will be explained using Figure 9. As shown in Figure 9, when the balloon group 2 is expanded, since there are two or more outer balloons B with different maximum outer diameters, multiple outer balloons B with different maximum outer diameters are arranged in the circumferential direction z of the outer circumference of the inner balloon A. As a result, the outer balloons b11 and b12 with the larger maximum outer diameters of the balloon group 2 come into contact with the inner wall of the blood vessel, while the outer balloons b13 and b14 with the smaller maximum outer diameters do not come into contact with the inner wall of the blood vessel. Therefore, a space is easily created between the inner wall of the blood vessel and the outer balloons b13 and b14 that do not come into contact with the inner wall of the blood vessel, allowing blood to perfuse. In addition, because the outer balloons b11 and b12 with the larger maximum outer diameters of the balloon group 2 come into contact with the inner wall of the blood vessel, the number of outer balloons B that come into contact with the inner wall of the balloon group 2 is limited to a portion, so the contact points between the outer balloons and the inner wall of the blood vessel are reduced, and the stress applied from the outer balloons B to the inner wall of the blood vessel can be concentrated. As a result, the stenosis can be reliably expanded.

[0052] As shown in Figure 9, when there are at least three outer balloons B, and two types of outer balloons with different maximum outer diameters are arranged in the circumferential direction z radially outward of the inner balloon A during the expansion of balloon group 2, it is preferable that the outer balloon b13 with the smaller maximum outer diameter is sandwiched between the outer balloons b11 and b12 with the larger maximum outer diameters. By sandwiching the outer balloon b13 with the smaller maximum outer diameter between the outer balloons b11 and b12 with the larger maximum outer diameters radially outward of the inner balloon A, the space formed between the inner wall of the blood vessel and the outer balloon that does not contact the inner wall of the blood vessel is distributed in the circumferential direction z on the outer circumference of the inner balloon A, thereby enabling stable blood perfusion.

[0053] When the balloon group 2 is expanded, the maximum outer diameters of the multiple outer balloons B may be, for example, two different sizes, three different sizes, or four or more different sizes. In particular, it is preferable that the maximum outer diameters of the outer balloons B be two different sizes.

[0054] As shown in Figure 9, when the balloon group 2 is expanded, if there are two types of outer balloons B with different maximum outer diameters, the ratio of the maximum outer diameter Db11 of the outer balloon b11 with a larger maximum outer diameter to the maximum outer diameter Db13 of the outer balloon b13 with a smaller maximum outer diameter (Db11 / Db13) is preferably greater than 1 and 5 or less, more preferably 1.1 or more, even more preferably greater than 1.1, particularly preferably 2 or more, most preferably 2.5 or more, more preferably 4.5 or less, and even more preferably 4 or less. That is, the ratio of the maximum outer diameter Db11 to the maximum outer diameter Db13 (Db11 / Db13) may be greater than 1 and 5 or less, may be between 1.1 and 4.5, may be greater than 1.1 and 4 or less, may be between 2 and 4, or may be between 2.5 and 4.

[0055] As shown in Figure 9, when the balloon group 2 is expanded, if there are two types of outer balloons B with different maximum outer diameters, the maximum outer diameter Db13 of the outer balloon b13 with the smaller maximum outer diameter is preferably, for example, 3 mm to 5 mm, and the maximum outer diameter Db11 of the outer balloon b11 with the larger maximum outer diameter is preferably, for example, 3.1 mm to 25 mm (particularly greater than 3.3 mm and 25 mm or less).

[0056] (3) will be explained using Figure 10. As shown in Figure 10, when the balloon group 2 is expanded, the maximum outer diameters of all the outer balloons B are the same, but because the maximum outer diameter of the outer balloons B is different from the maximum outer diameter of the inner balloon A, the inner balloons A and outer balloons B with different maximum outer diameters can be appropriately combined and adjusted, making it easier to adjust the maximum outer diameter of the balloon group 2. The fact that the maximum outer diameters of all the outer balloons B are the same means that the maximum outer diameters of the multiple outer balloons B are approximately the same, and specifically, it means that the maximum outer diameter of the outer balloon B with the largest maximum outer diameter is between 100% and 110% of the maximum outer diameter of the outer balloon B with the smallest maximum outer diameter among the outer balloons B.

[0057] In case (3), when the balloon group 2 is expanded, the maximum outer diameter of the outer balloon B may be larger than or smaller than the maximum outer diameter of the inner balloon A, but it is preferable that it be smaller. By having the maximum outer diameters of the multiple outer balloons B be smaller than the maximum outer diameters of the inner balloons A, the inner balloons A can be expanded at high pressure, thereby ensuring that the constricted area is expanded.

[0058] When the maximum outer diameter of multiple outer balloons B is greater than the maximum outer diameter of inner balloon A, the ratio of the maximum outer diameter Db21 of outer balloon b21 to the maximum outer diameter Da of inner balloon A (Db21 / Da) is preferably greater than 1 and 4.5 or less, more preferably 1.1 or more, even more preferably greater than 1.1, particularly preferably 1.2 or more, more preferably 4 or less, and even more preferably 3 or less. That is, the ratio of the maximum outer diameter Db21 to the maximum outer diameter Da (Db21 / Da) may be greater than 1 and 4.5 or less, 1.1 to 4, greater than 1.1 and 3 or less, or 1.2 to 3.

[0059] When the maximum outer diameter of multiple outer balloons B is greater than the maximum outer diameter of inner balloon A, the maximum outer diameter Da of inner balloon A is preferably, for example, 3 mm to 5 mm, and the maximum outer diameter Db21 of outer balloon b21 is preferably, for example, 3.1 mm to 13.5 mm (particularly greater than 3.3 mm and 13.5 mm or less).

[0060] When the maximum outer diameter of multiple outer balloons B is smaller than the maximum outer diameter of inner balloon A, the ratio of the maximum outer diameter Db21 of outer balloon B to the maximum outer diameter Da of inner balloon A (Db21 / Da) is preferably, for example, 0.01 or more and less than 1, more preferably 0.03 or more, even more preferably 0.05 or more, more preferably less than 0.9, even more preferably 0.2 or less, and particularly preferably 0.1 or less. That is, the ratio of the maximum outer diameter Db21 to the maximum outer diameter Da (Db21 / Da) may be, for example, 0.01 or more and less than 1, 0.03 or more and less than 0.9, 0.05 to 0.2, or 0.05 to 0.1.

[0061] When the maximum outer diameter of multiple outer balloons B is smaller than the maximum outer diameter of inner balloon A, the maximum outer diameter Da of inner balloon A is preferably, for example, 3 mm to 20 mm, and the maximum outer diameter Db21 of outer balloon b21 is preferably, for example, 1.0 mm to 5 mm.

[0062] Examples of materials that make up the inner balloon A and the outer balloon B include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester resins such as polyethylene terephthalate and polyester elastomer; polyurethane resins such as polyurethane and polyurethane elastomer; polyphenylene sulfide resin; polyamide resins such as polyamide and polyamide elastomer; fluororesin; silicone resin; natural rubber such as latex rubber; and the like. Only one of these may be used, or two or more may be used in combination. In particular, at least one of polyamide resins, polyester resins, and polyurethane resins is preferred for the materials that make up the inner balloon A and the outer balloon B.

[0063] For the materials constituting the inner balloon A and the outer balloon B, it is preferable to use elastomer resins from the viewpoint of thinness and flexibility. For example, among polyamide resins, nylon 12 and nylon 11 are suitable as materials for constituting the inner balloon A and the outer balloon B. Nylon 12 is more preferable because it can be molded relatively easily during blow molding. Furthermore, from the viewpoint of thinness and flexibility of the inner balloon A and the outer balloon B, polyamide elastomers such as polyether ester amide elastomers and polyamide ether elastomers are preferably used. Among these, polyether ester amide elastomers are preferably used because they have high yield strength and provide good dimensional stability for the inner balloon A and the outer balloon B.

[0064] The materials constituting the inner balloon A and the outer balloon B may be the same, but it is preferable that they be different, and it is preferable to select the materials such that the pressure resistance value P2 of the outer balloon B is greater than the pressure resistance value P1 of the inner balloon A. The materials constituting multiple outer balloons B may each be different, but it is preferable that they be the same. By being the same, the degree of expansion and hardness of each outer balloon B can be made to be of a similar degree.

[0065] Examples of materials that make up the shaft 10 include polyamide resin, polyester resin, polyurethane resin, polyolefin resin, fluororesin, vinyl chloride resin, silicone resin, natural rubber, etc. Only one of these may be used, or two or more may be used in combination. In particular, at least one of polyamide resin, polyolefin resin, and fluororesin is preferred for the material that makes up the shaft 10. By using any of polyamide resin, polyolefin resin, or fluororesin, the slipperiness of the surface of the shaft 10 is increased, which can improve the insertion of the balloon catheter 1 into the blood vessel.

[0066] As shown in Figure 1, an example of a balloon catheter 1 is a so-called rapid exchange type balloon catheter 1, which has a guidewire port 50 located midway from the distal to the proximal end of the shaft 10, and a guidewire insertion passage from the guidewire port 50 to the distal end of the shaft 10. As shown in Figure 1, the balloon catheter 1 may also have a hub 5 on the proximal end, and the hub 5 may be provided with a fluid injection section 6 for injecting fluid to expand or deflate the balloon group 2.

[0067] In the case of a rapid exchange type balloon catheter 1, the shaft 10 of the balloon catheter 1 preferably has a distal shaft 15 and a proximal shaft 16 positioned proximal to the distal shaft 15, and the distal shaft 15 and the proximal shaft 16 may be made of separate components. If the distal shaft 15 and the proximal shaft 16 are separate components, the proximal shaft 16 may be made of resin or metal.

[0068] In the case of a rapid exchange type balloon catheter 1, the outer walls of the proximal shaft 16 and / or distal shaft 15 may be coated, or both the proximal shaft 16 and distal shaft 15 may be coated. The coating can be hydrophilic or hydrophobic depending on the purpose, and can be applied by immersing the shaft 10 in a hydrophilic or hydrophobic coating agent, applying a hydrophilic or hydrophobic coating agent to the outer wall of the shaft 10, or covering the outer wall of the shaft 10 with a hydrophilic or hydrophobic coating agent. The coating agent may contain drugs or additives.

[0069] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and methyl vinyl ether maleic anhydride copolymer, or hydrophilic coating agents made from any combination thereof. Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), ethylene fluoride propylene (FEP), perfluoroalkoxyalkanes (PFA), silicone oil, hydrophobic urethane resins, carbon coatings, diamond coatings, diamond-like carbon (DLC) coatings, ceramic coatings, and substances with low surface free energy terminated with alkyl groups or perfluoroalkyl groups.

[0070] Although not shown in the figures, the balloon catheter 1 may be a so-called over-the-wire type balloon catheter 1 having a guidewire insertion passage extending from the distal to the proximal end of the shaft 10. In the case of an over-the-wire type balloon catheter 1, it is preferable that the inflation lumen and guidewire lumen extend to a hub 5 located on the proximal end, and that the proximal opening of each lumen is provided in a bifurcated hub 5. In the case of an over-the-wire type balloon catheter 1, it is preferable that the outer wall of the shaft 10 is coated. For details on the materials and coatings constituting the shaft 10, refer to the description of the rapid-exchange type balloon catheter 1.

[0071] A tip member 60 may be provided at the distal end of the balloon catheter 1, as shown in Figure 1. The tip member 60 may be provided at the distal end of the balloon catheter 1 by being connected to the distal end of the inner balloon A as a separate member from the shaft 10, or the distal end of the shaft 10 may function as the tip member 60 by extending distally beyond the distal end 24d of the distal tapered portion 24 of the inner balloon A.

[0072] The balloon catheter 1 can be used, for example, to dilate blood vessels. The balloon catheter 1 can also be used, for example, to dilate the aortic valve, deform a bioprosthetic valve implanted in the heart, or destroy the bioprosthetic valve. Vascular stenosis can occur, for example, in the aortic valve. When stenosis occurs in the aortic valve, the aortic valve is removed and a new bioprosthetic valve is implanted. However, implanted bioprosthetic valves deteriorate over time and need to be replaced every 5 to 10 years. When a new bioprosthetic valve (artificial valve) is implanted transcatheterally due to deterioration of a surgically implanted bioprosthetic valve (artificial valve), the valve orifice area may become smaller. Therefore, the size of the new bioprosthetic valve must be smaller than the deteriorated bioprosthetic valve, leading to decreased blood flow, a pressure difference before and after the bioprosthetic valve, and a strain on the heart. Therefore, by using the balloon catheter 1 to deform or destroy a bioprosthetic valve implanted in the heart, a larger bioprosthetic valve can be implanted, improving the pressure difference before and after the bioprosthetic valve.

[0073] This application claims the benefit of priority based on Japanese Patent Application No. 2025-057075, filed on 28 March 2025. The entire contents of the specification of the above Japanese Patent Application No. 2025-057075 are incorporated herein by reference.

[0074] 1 Balloon catheter 2 Balloon group 5 Hub 6 Fluid injection section 10 Shaft 10p Proximal shaft section 10d Distal shaft section 15 Distal shaft 16 Proximal shaft 21 Proximal sleeve section 22 Proximal tapered section 22d Distal end of proximal tapered section 22p Proximal end of proximal tapered section 23 Straight section 24 Distal tapered section 24d Distal end of distal tapered section 24p Proximal end of distal tapered section 25 Distal sleeve section 50 Guidewire port 60 Tip member A Inner balloon ALe Length of the straight section of the inner balloon in the longitudinal direction B Outer balloon BLE Length of the straight section of the outer balloon in the longitudinal direction b1, b2, b3, b4, b11-b14, b21-b23 Outer balloon Da Maximum outer diameter of inner balloon Db1, Db2, Db11-Db14, Db21-Db23 Maximum outer diameter of outer balloon G Midpoint La Length of inner balloon in the longitudinal direction Lb Length of outer balloon in the longitudinal direction x Longitudinal direction y Radial direction z Circumferential direction D １ Diameter D of the first shortest circumscribed circle ２ Diameter of the second shortest circumscribed circle: D3 Diameter of the third shortest circumscribed circle: V1 First shortest circumscribed circle: V2 Second shortest circumscribed circle: Va1 First inner virtual circle: Va2 Second inner virtual circle: Vb1 First outer virtual circle: Vb2 Second outer virtual circle: D Ｖ１ Diameter D of the first virtual shortest circumscribed circle Ｖ２ Diameter D of the second virtual shortest circumscribed circle Ｖ３ The diameter V of the third virtual shortest circumscribed circle ｖ１ First virtual shortest circumscribed circle V ｖ２ Second virtual shortest circumscribed circle

Claims

1. A balloon catheter comprising: a shaft extending longitudinally from proximal to distal; and a balloon group disposed at the distal end of the shaft and composed of a plurality of balloons, wherein the plurality of balloons constituting the balloon group have an inner balloon and N (where N is an integer of 2 or more) outer balloons arranged radially outward of the inner balloon and aligned in the circumferential direction of the inner balloon; the inner balloon and the outer balloons each have a straight section, a proximal tapered section located proximal to the straight section, and a distal tapered section located distal to the straight section; the balloon group has a first expanded state in which the balloon group is pressurized by a first pressure and a second expanded state in which the balloon group is pressurized by a second pressure higher than the first pressure; and the diameter D of the first shortest circumscribed circle of the balloon group at the midpoint of the balloon group in the longitudinal direction in the first expanded state. １ The following requirement 1 is met, and the diameter D of the second shortest circumscribed circle of the balloon group at the midpoint in the second expanded state is... ２ The balloon catheter satisfies requirement 2 below. (Requirement 1) A first inner virtual circle whose diameter is the outer diameter of the inner balloon at the midpoint when the inner balloon is pressed by the first pressure in a state in which it is alone and not in contact with the other balloons constituting the balloon group, and a first outer virtual circle whose diameter is the outer diameter of the outer balloon at the midpoint when the outer balloon is pressed by the first pressure in a state in which it is alone and not in contact with the other balloons constituting the balloon group, wherein the diameter D of the first shortest circumscribed circle １ The diameter D of the first virtual shortest circumscribed circle of the first virtual balloon group, which is formed by arranging N first outer virtual circles in the circumferential direction of the first inner virtual circle radially outward from the first inner virtual circle. Ｖ１ Smaller than (Requirement 2) A second inner virtual circle whose diameter is the outer diameter of the inner balloon at the midpoint when the inner balloon is pressurized by the second pressure in a state in which it is alone and not in contact with the other balloons that make up the balloon group, and a second outer virtual circle whose diameter is the outer diameter of the outer balloon at the midpoint when the outer balloon is pressurized by the second pressure in a state in which it is alone and not in contact with the other balloons that make up the balloon group, wherein the diameter D of the second shortest circumscribed circle ２ The diameter D of the second virtual shortest circumscribed circle of the second virtual balloon group, which is formed by arranging N of the second outer virtual circles in the circumferential direction of the second inner virtual circle radially outward from the second inner virtual circle. Ｖ２ It is larger than that.

2. The balloon catheter according to claim 1, wherein the outer diameter of the balloon group at the midpoint in the second expanded state is greater than the outer diameter of the balloon group at the portion where the distal end of the proximal tapered portion of the outer balloon is located, and the outer diameter of the balloon group at the portion where the proximal end of the distal tapered portion of the outer balloon is located.

3. The balloon catheter according to claim 1 or 2, wherein the length of the inner balloon in the longitudinal direction is shorter than the length of the outer balloon in the longitudinal direction.

4. The balloon catheter according to claim 1 or 2, wherein the shaft has a proximal shaft portion located proximal to the inner balloon and a distal shaft portion located distal to the inner balloon, the inner balloon and the outer balloon each have a proximal sleeve portion located proximal to the proximal tapered portion and a distal sleeve portion located distal to the distal tapered portion, the proximal sleeve portion of the inner balloon and the proximal sleeve portion of the outer balloon are connected to the proximal shaft portion, and the distal sleeve portion of the inner balloon and the distal sleeve portion of the outer balloon are connected to the distal shaft portion, respectively.

5. The balloon catheter according to claim 1 or 2, wherein the length in the longitudinal direction of the straight tube portion of the inner balloon is shorter than the length in the longitudinal direction of the straight tube portion of the outer balloon.

6. The balloon catheter according to claim 1 or 2, wherein the distal end of the proximal tapered portion of the inner balloon is located distal to the distal end of the proximal tapered portion of the outer balloon, and the proximal end of the distal tapered portion of the inner balloon is located proximal to the proximal end of the distal tapered portion of the outer balloon.

7. The balloon catheter according to claim 1 or 2, wherein, when the inner balloon and the balloon group are expanded, adjacent outer balloons constituting the balloon group are in contact with each other.

8. The balloon catheter according to claim 1 or 2, wherein, when the inner balloon and the balloon group are expanded, the maximum outer diameters of all the outer balloons constituting the balloon group are the same, and the maximum outer diameter of the outer balloons is the same as the maximum outer diameter of the inner balloon.

9. The balloon catheter according to claim 1 or 2, wherein, when the balloon group is expanded, there are two or more outer balloons constituting the balloon group that have different maximum outer diameters.

10. The balloon catheter according to claim 9, wherein, when the inner balloon and the balloon group are expanded, two outer balloons of different maximum outer diameters are arranged circumferentially around the outer circumference of the inner balloon, and the outer balloon with the smaller maximum outer diameter is sandwiched between the outer balloons with the larger maximum outer diameter.

11. The balloon catheter according to claim 1 or 2, wherein, when the inner balloon and the balloon group are expanded, the maximum outer diameters of all the outer balloons constituting the balloon group are the same, and the maximum outer diameter of the outer balloons is different from the maximum outer diameter of the inner balloon.

12. The balloon catheter according to claim 11, wherein the maximum outer diameter of the outer balloon constituting the balloon group is smaller than the maximum outer diameter of the inner balloon.

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