Balloon catheter

Abstract

Provided is a balloon catheter having: an inner balloon disposed at a distal portion of a shaft; and a balloon group composed of a plurality of outer balloons aligned in the circumferential direction of the inner balloon radially outward of the inner balloon, the balloons being less likely to be damaged by a marker.　In the balloon catheter, the proximal end of the proximal tapered portion of the inner balloon is located distal to the proximal end of the proximal tapered portion of the outer balloons and proximal to the distal end of the proximal tapered portion of the outer balloons, the distal end of the distal tapered portion of the inner balloon is located proximal to the distal end of the distal tapered portion of the outer balloons and distal to the proximal end of the distal tapered portion of the outer balloons, a first marker is disposed at a portion of the shaft located in the proximal tapered portion of the inner balloon, and a second marker is disposed at a portion of the shaft located in the distal tapered portion of the inner balloon.

Description

Balloon Catheter

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

[0002] Diseases such as angina pectoris and myocardial infarction are caused by the formation of a stenotic lesion hardened due to calcification or the like on the inner wall of a blood vessel. As one of the treatment methods for these conditions, there is angioplasty in which a stenotic lesion is dilated using a balloon catheter. Angioplasty is sometimes referred to as Percutaneous Transluminal Angioplasty (PTA) or Percutaneous Transluminal Coronary Angioplasty (PTCA). Angioplasty is a minimally invasive therapy that does not require thoracotomy like bypass surgery, and is widely performed.

[0003] A balloon catheter used in angioplasty includes at least a shaft extending longitudinally from a proximal side to a distal side, a balloon disposed at a distal portion of the shaft, and a marker for grasping the position of the balloon. An example of such a balloon catheter is described in Patent Document 1. FIG. 42 of Patent Document 1 describes an expansion device including an inner balloon member and a plurality of outer balloon members.

[0004] US Patent Application Publication No. 2012 / 0209375

[0005] As described in Patent Document 1, a balloon catheter includes an inner balloon disposed at a distal portion of a shaft, and a balloon group composed of a plurality of outer balloons arranged side by side in a circumferential direction of the inner balloon at a radially outer side of the inner balloon. When the balloons are expanded, the diameter of the balloons can be increased, so a stenotic lesion or the like can be greatly expanded. In order to grasp the position of such balloons, a marker is usually disposed on the shaft. The markers are disposed on the shaft corresponding to the distal end and proximal end of the outer balloon in order to grasp the position of the outer balloon. If the marker accidentally comes into contact with the outer balloon when the outer balloon is expanded, the outer balloon may be damaged.

[0006] The problem to be solved by this disclosure is to provide a balloon catheter having an inner balloon located at the distal end of a shaft, and a balloon group consisting of a plurality of outer balloons arranged radially outward of the inner balloon and aligned in the circumferential direction of the inner balloon, wherein the balloon is less likely to be damaged by a marker.

[0007] The present disclosure is as follows: [1] A balloon catheter comprising: a shaft extending longitudinally from proximal to distal; an inner balloon disposed at the distal end of the shaft; a balloon group comprising a plurality of outer balloons arranged radially outward of the inner balloon and aligned circumferentially with respect to the inner balloon; and a first marker and a second marker disposed outside the shaft and inside the inner balloon, wherein the inner balloon and the outer balloon 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 proximal end of the proximal tapered section of the inner balloon being distal to the proximal end of the proximal tapered section of the outer balloon and proximal to the distal end of the proximal tapered section of the outer balloon, A balloon catheter wherein the distal end of the distal tapered portion of the inner balloon is located proximal to the distal end of the distal tapered portion of the outer balloon and distal to the proximal end of the distal tapered portion of the outer balloon, the first marker is located on the portion of the shaft located in the proximal tapered portion of the inner balloon, and the second marker is located on the portion of the shaft located in the distal tapered portion of the inner balloon. [2] The balloon catheter according to [1] wherein the distal end of the first marker is located distal to the proximal end of the straight portion of the outer balloon, and the proximal end of the second marker is located proximal to the distal end of the straight portion of the outer balloon. [3] The balloon catheter according to [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. [4] The balloon catheter according to any one of [1] to [3], wherein the longitudinal length of the straight portion of the inner balloon is shorter than the longitudinal length of the straight portion of the outer balloon.[5] A balloon catheter according to any one of [1] to [4], further comprising a third marker located outside the shaft and inside the inner balloon, wherein the third marker is located on the portion of the shaft that is located in the straight tube portion of the inner balloon. [6] A balloon catheter according to [5], wherein the third marker is located on the portion of the shaft that is located at the midpoint of the length in the longitudinal direction of the straight tube portion of the outer balloon. [7] A 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, at least one of the plurality of outer balloons constituting the balloon group is in contact with the outer circumferential surface of the inner balloon. [9] A balloon catheter according to any one of [1] to [8], 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.

[10] A balloon catheter according to any one of [1] to [8], wherein when the balloon group is expanded, there are two or more outer balloons constituting the balloon group that have different maximum outer diameters.

[11] A balloon catheter according to

[10] , wherein when the inner balloon and the balloon group are expanded, two outer balloons with different maximum outer diameters are arranged in the circumferential direction 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.

[12] A balloon catheter according to any one of [1] to [8], 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.

[13] A balloon catheter according to

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

[0008] According to this disclosure, a balloon catheter can be provided in which the balloon is less likely to be damaged by the marker.

[0009] Figure 1 is a side view (partially a fluoroscopic view) of a balloon catheter. Figure 2 is a magnified 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 partially abbreviated view of the magnified view shown in Figure 2. Figure 5 is a cross-sectional view of a balloon different from the balloons shown in Figures 1 and 2. Figure 6 is a cross-sectional view of a balloon 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, an inner balloon positioned at the distal end of the shaft, a balloon group consisting of a plurality of outer balloons arranged radially outward from the inner balloon and aligned circumferentially with respect to the inner balloon, and a first marker and a second marker positioned outside the shaft and inside the inner balloon, wherein the inner balloon and outer balloon 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 proximal end of the proximal tapered section of the inner balloon being distal to the proximal end of the proximal tapered section of the outer balloon and proximal to the distal end of the proximal tapered section of the outer balloon, and the distal end of the distal tapered section of the inner balloon being proximal to the distal end of the distal tapered section of the outer balloon and distal to the proximal end of the distal tapered section of the outer balloon. The key feature is that the first marker is positioned on the shaft portion located in the proximal tapered section of the inner balloon, and the second marker is positioned on the shaft portion located in the distal tapered section of the inner balloon. Because the first and second markers are positioned inside the inner balloon in this way, the markers are covered by the inner balloon and do not come into contact with the outer balloon even when the outer balloon is expanded. As a result, the outer balloon is less likely to be damaged by the markers.

[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 an enlarged 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 an enlarged 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 extending longitudinally x from proximal to distal, and an inner balloon A and a plurality of outer balloons b1 to b4 etc. arranged at the distal end of the shaft 10. In this specification, the plurality of outer balloons b1 to b4 etc. may be collectively referred to as "balloon group B". In this specification, the inner balloon A and balloon group B may be collectively referred to as "balloon 2". The plurality of outer balloons b1 to b4 etc. are arranged radially outward of the inner balloon A and aligned in the circumferential direction z of the inner balloon A. A first marker 71 and a second marker 72 are arranged radially outward of the shaft 10 and radially inward of the inner balloon A. The position of the distal end of the tapered portion 22 of balloon group B can be determined by the placement of the first marker 71. The position of the proximal end of the tapered portion 24 of balloon group B can be determined by the placement of the second marker 72. The first marker 71 and the second marker 72 may be collectively referred to as "marker 70". A third marker 73 may be further positioned radially outward from the shaft 10 and radially inward from the inner balloon A, as will be described later.

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

[0016] In the balloon catheter 1, the length of the inner balloon A in the longitudinal direction x at the proximal tapered portion 22 is ALp1 and the length in the radial direction y is ALp2, the length of the outer balloon in the longitudinal direction x at the proximal tapered portion 22 is BLp1 and the length in the radial direction y is BLp2, the length of the inner balloon A in the longitudinal direction x at the distal tapered portion 24 is ALd1 and the length in the radial direction y is ALd2, and the length of the outer balloon in the longitudinal direction x at the distal tapered portion 24 is BLd1 and the length in the radial direction y is BLd2.

[0017] As shown in Figures 2 and 4, the proximal end 22p of the proximal tapered portion 22 of the inner balloon A is located distal to the proximal end 22p of the proximal tapered portion 22 of the outer balloon and also proximal to the distal end 23p of the proximal tapered portion 22 of the outer balloon, and the distal end 24d of the distal tapered portion 24 of the inner balloon A is located proximal to the distal end 24d of the distal tapered portion 24 of the outer balloon and also distal to the proximal end 23d of the distal tapered portion 24 of the outer balloon. With the tapered portions of the inner balloon A and the outer balloon arranged in this manner, the first marker 71 is positioned on the portion of the shaft 10 located on the proximal tapered portion 22 of the inner balloon A, and the second marker 72 is positioned on the portion of the shaft 10 located on the distal tapered portion 24 of the inner balloon A. As described above, because the first marker 71 and the second marker 72 are positioned inside the inner balloon A, the marker 70 is covered by the inner balloon, and therefore the marker 70 does not come into contact with the outer balloon even when the outer balloon expands. As a result, the outer balloon is less likely to be damaged by the marker 70.

[0018] As shown in Figure 4, the distal end of the first marker 71 may be located distal to the proximal end 23p of the straight section 23 of the outer balloon and proximal to the proximal end 23p of the straight section 23 of the inner balloon A, and the proximal end of the second marker 72 may be located proximal to the distal end 23d of the straight section 23 of the outer balloon and proximal to the distal end 23d of the straight section 23 of the inner balloon A. This allows the position of the straight section 23 of the outer balloon that contributes to the dilation of stenosis, etc., to be confirmed, so that the procedure can be performed safely.

[0019] As shown in Figure 4, the balloon catheter 1 may further have a third marker 73 positioned outside the shaft 10 and inside the inner balloon A. The third marker 73 may be positioned on the part of the shaft 10 located at the straight section 23 of the inner balloon A. This makes it possible to confirm the position of the straight section 23 of the balloon 2 that contributes to the dilation of stenosis, etc., thereby making the procedure easier to perform safely.

[0020] If the balloon catheter 1 has a third marker 73, the third marker 73 may be positioned on the shaft 10 at the midpoint of the length in the longitudinal direction x of the straight tube portion 23 of the inner balloon A. This makes it possible to confirm the midpoint of the straight tube portion 23 of the inner balloon A, thus facilitating safer procedures.

[0021] The shapes of the marker 70 and the third marker 73 are preferably cylindrical. Examples of cylindrical shapes include cylindrical, polygonal cylindrical, C-shaped cross-section with a cut in the cylinder, and coil shape with a wire wound around it.

[0022] Marker 70 and the third marker 73 may contain an X-ray opaque material. Examples of X-ray opaque materials include lead, barium, iodine, tungsten, gold, platinum, iridium, stainless steel, titanium, and cobalt-chromium alloy. These may be used individually or in combination of two or more.

[0023] The length of the inner balloon A in the longitudinal direction x may be less than or equal to the length of the outer balloon in the longitudinal direction x. As shown in Figure 4, when the length of the inner balloon A in the longitudinal direction x from the proximal end 22p of the proximal tapered portion 22 to the distal end 24d of the distal tapered portion 24 is AL, and the length of the outer balloon in the longitudinal direction x from the proximal end 22p of the proximal tapered portion 22 to the distal end 24d of the distal tapered portion 24 is BL, the length of the inner balloon A in the longitudinal direction x, AL, may be less than or equal to the length of the outer balloon in the longitudinal direction x. This makes it less likely for the positions of the tapered portion of the inner balloon A and the tapered portion of the outer balloon to overlap in the longitudinal direction x when the balloon 2 is deflated, thus reducing the outer diameter when the balloon 2 is deflated. As a result, the extraction load can be reduced.

[0024] The length AL of the inner balloon A in the longitudinal direction x may be 100% or less, preferably 95% or less, and more preferably 90% or less, of the length BL of the outer balloon in the longitudinal direction x. The length AL of the inner balloon A in the longitudinal direction x may be 50% or more, preferably 60% or more, and more preferably 70% or more, of the length BL of the outer balloon in the longitudinal direction x. That is, the length AL of the inner balloon A in the longitudinal direction x may be 50 to 100%, 60 to 95%, or 70 to 90% of the length BL of the outer balloon in the longitudinal direction x.

[0025] As shown in Figure 4, the distal end 23p of the proximal tapered portion 22 of the inner balloon A may be located distal to the distal end 23p of the proximal tapered portion 22 of the outer balloon, and the proximal end 23d of the distal tapered portion 24 of the inner balloon A may be located proximal to the proximal end 23d of the distal tapered portion 24 of the outer balloon. This makes it less likely for the positions of the tapered portions of the inner balloon A and the outer balloon to overlap in the longitudinal direction x when the balloon 2 is deflated, thus reducing the outer diameter when the balloon 2 is deflated. As a result, the extraction load can be reduced.

[0026] As shown in Figure 4, the length ALp1 of the proximal tapered portion 22 of the inner balloon A in the longitudinal direction x may be longer than the length BLp1 of the proximal tapered portion 22 of the outer balloon in the longitudinal direction x, and the length ALd1 of the distal tapered portion 24 of the inner balloon A in the longitudinal direction x may be longer than the length BLd1 of the distal tapered portion 24 of the outer balloon in the longitudinal direction x. This increases the proportion of the tapered portion of the inner balloon A (the sum of the length of the proximal tapered portion 22 in the longitudinal direction x and the length of the distal tapered portion 24 in the longitudinal direction x) to the length AL of the inner balloon A, making it easier to place the marker 70 inside the inner balloon A.

[0027] The length ALp1 of the proximal tapered portion 22 of the inner balloon A in the longitudinal direction x is preferably 110% or more, more preferably 120% or more, and even more preferably 130% or more, of the length BLp1 of the proximal tapered portion 22 of the outer balloon in the longitudinal direction x. By having a length ALp1 of 110% or more of the length BLp1, the marker 70 can be reliably covered by the inner balloon A. The length ALp1 of the proximal tapered portion 22 of the inner balloon A in the longitudinal direction x is preferably 250% or less, more preferably 240% or less, and even more preferably 230% or less, of the length BLp1 of the proximal tapered portion 22 of the outer balloon in the longitudinal direction x. By having a length ALp1 of 250% or less of the length BLp1, the outer diameter when the balloon 2 is deflated can be reduced, and as a result, the extraction load can be reduced. That is, the length ALp1 of the proximal tapered portion 22 of the inner balloon A in the longitudinal direction x may be 110 to 250%, 120 to 240%, or 130 to 230% of the length BLp1 of the proximal tapered portion 22 of the outer balloon in the longitudinal direction x. The length ALd1 of the distal tapered portion 24 of the inner balloon A in the longitudinal direction x is preferably 110% or more, more preferably 120% or more, and even more preferably 130% or more of the length BLd1 of the distal tapered portion 24 of the outer balloon in the longitudinal direction x. By having a length ALd1 of 110% or more of the length BLd1, the marker 70 can be reliably covered by the inner balloon A. The length ALd1 of the distal tapered portion 24 of the inner balloon A in the longitudinal direction x is preferably 250% or less, more preferably 240% or less, and even more preferably 230% or less of the length BLd1 of the distal tapered portion 24 of the outer balloon in the longitudinal direction x. By having a length ALd1 of 250% or less of the length BLd1, the outer diameter when the balloon 2 is deflated can be reduced, and as a result, the extraction load can be reduced.That is, the length ALd1 of the distal tapered portion 24 of the inner balloon A in the longitudinal direction x may be 110 to 250%, 120 to 240%, or 130 to 230% of the length BLd1 of the distal tapered portion 24 of the outer balloon in the longitudinal direction x.

[0028] The balloon catheter 1 may have a ratio (ALp2 / ALp1) of the length ALp1 in the longitudinal direction x to the length ALp2 in the radial direction y at the proximal tapered portion 22 of the inner balloon A that is smaller than the ratio (BLp2 / BLp1) of the length BLp1 in the longitudinal direction x to the length BLp2 in the radial direction y at the proximal tapered portion 22 of the outer balloon, and a ratio (ALd2 / ALd1) of the length ALd1 in the longitudinal direction x to the length ALd2 in the radial direction y at the distal tapered portion 24 of the inner balloon A that is smaller than the ratio (BLd2 / BLd1) of the length BLd1 in the longitudinal direction x to the length BLd2 in the radial direction y at the distal tapered portion 24 of the outer balloon.

[0029] On the proximal side of balloon 2, the ratio value of the inner balloon A (ALp2 / ALp1) is smaller than the ratio value of the outer balloon (BLp2 / BLp1), so the angle of the proximal tapered portion 22 of the inner balloon A is smaller than the angle of the proximal tapered portion 22 of the outer balloon. On the distal side of balloon 2, the ratio value of the inner balloon A (ALd2 / ALd1) is smaller than the ratio value of the outer balloon (BLd2 / BLd1), so the angle of the distal tapered portion 24 of the inner balloon A is smaller than the angle of the distal tapered portion 24 of the outer balloon. Thus, because the angle of the tapered portion of the inner balloon A is smaller than the angle of the tapered portion of the outer balloon at both the proximal and distal ends of the balloon 2, even when the positions of the tapered portions of the inner balloon A and the outer balloon are offset in the longitudinal direction x with respect to the longitudinal direction x of the shaft 10, the marker 70 indicating the position of the outer balloon can be placed on the shaft 10 inside the inner balloon A. Therefore, even if the marker 70 were to detach from the shaft 10 in the body lumen, the detached marker 70 would remain inside the inner balloon A, preventing it from being left behind in the body. Furthermore, by offsetting the positions of the tapered portions of the inner balloon A and the outer balloon in the longitudinal direction x, the bulk of the balloon 2 when it is deflated is reduced, and the outer diameter of the balloon 2 can be reduced, thus reducing the load when removing the balloon 2 from the body lumen.

[0030] The ratio value (ALp2 / ALp1) at the proximal tapered portion 22 of the inner balloon A may be, for example, 0.05 to 1.00. The ratio value (BLp2 / BLp1) at the proximal tapered portion 22 of the outer balloon may be, for example, 0.10 to 2.00. The ratio value (ALd2 / ALd1) at the distal tapered portion 24 of the inner balloon A may be, for example, 0.05 to 1.00. The ratio value (BLd2 / BLd1) at the distal tapered portion 24 of the outer balloon may be, for example, 0.10 to 2.00. The balloon catheter 1 may have a ratio (ALp2 / ALp1) of the length ALp1 in the longitudinal direction x to the length ALp2 in the radial direction y at the proximal tapered portion 22 of the inner balloon A that is 0.01 or more smaller than the ratio (BLp2 / BLp1) of the length BLp1 in the longitudinal direction x to the length BLp2 in the radial direction y at the proximal tapered portion 22 of the outer balloon (BLp2 / BLp1), 0.05 or more smaller than the ratio (BLp2 / BLp1) of the length BLp1 in the longitudinal direction x to the length BLp2 in the radial direction y at the proximal tapered portion 22 of the outer balloon. That is, the ratio value (ALp2 / ALp1) may be smaller than the ratio value (BLp2 / BLp1) by 0.01 to 1.3, by 0.05 to 1, by 0.1 to 0.8, or by 0.1 to 0.5. The balloon catheter 1 may have a ratio (ALd2 / ALd1) of the length ALd1 in the longitudinal direction x to the length ALd2 in the radial direction y at the distal tapered portion 24 of the inner balloon A that is 0.01 or more smaller than the ratio (BLd2 / BLd1) of the length BLd1 in the longitudinal direction x to the length BLd2 in the radial direction y at the distal tapered portion 24 of the outer balloon (BLd2 / BLd1), 0.05 or more smaller than the ratio (BLd2 / BLd1) of the length BLd1 in the longitudinal direction x to the length BLd2 in the radial direction y at the distal tapered portion 24 of the outer balloon.That is, the ratio value (ALd2 / ALd1) may be smaller than the ratio value (BLd2 / BLd1) by a range of 0.01 to 1.3, by a range of 0.05 to 1, by a range of 0.1 to 0.8, or by a range of 0.1 to 0.5.

[0031] As shown in Figure 4, 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 in the longitudinal direction x. This allows the positions of the tapered portion of the inner balloon A and the tapered portion of the outer balloon to be offset in the longitudinal direction x, thereby reducing the outer diameter when the balloon 2 is deflated and reducing the extraction load.

[0032] The length ALe of the straight tube portion 23 of the inner balloon A 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 BLE of the straight tube portion 23 of the outer balloon in the longitudinal direction x. The length ALe of the straight tube portion 23 of the inner balloon A in the longitudinal direction x is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more of the length BLE of the straight tube portion 23 of the outer balloon in the longitudinal direction x. That is, the length ALe of the straight tube portion 23 of the inner balloon A in the longitudinal direction x may be 20 to 95%, 25 to 90%, or 30 to 85% of the length BLE of the straight tube portion 23 of the outer balloon in the longitudinal direction x.

[0033] 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 in the longitudinal direction x may be, for example, 30 to 50 mm, 25 to 45 mm, or 28 to 43 mm.

[0034] As shown in Figures 1 to 3, the balloon catheter 1 has multiple outer balloons, and the multiple outer balloons (balloon group B) are arranged radially outward from the inner balloon A, aligned in the circumferential direction z of the inner balloon A. The arrangement of the inner balloon A and balloon group B will be explained using Figures 3, 5, and 6. Figure 3 is a cross-sectional view of the balloon 2 shown in Figures 1 and 2 at the position of line III-III. Figures 5 and 6 are cross-sectional views of the balloon 2 at the position of line III-III with a different configuration from the balloon 2 shown in Figures 1 and 2.

[0035] The balloon catheter 1 shown in Figure 3 consists of one inner balloon A and six outer balloons, with the six outer balloons forming balloon group B. In Figure 3, for the sake of explanation, four of the six outer balloons are labeled b1 to b4. When inner balloon A and outer balloon b1 are expanded, the maximum outer diameter of inner balloon A is denoted as Da, and the maximum outer diameter of outer balloon b1 is denoted as Db1 (the same applies hereafter).

[0036] The balloon catheter 1 shown in Figure 5 consists of one inner balloon A and eight outer balloons, with the eight outer balloons forming balloon group B. In Figure 5, for the sake of explanation, four of the eight outer balloons are labeled b11 to b14.

[0037] The balloon catheter 1 shown in Figure 6 consists of one inner balloon A and 20 outer balloons, with the 20 outer balloons forming balloon group B. In Figure 6, for the sake of explanation, three of the 20 outer balloons are labeled b21 to b23.

[0038] As shown in Figure 3, the balloon catheter 1 has a balloon group B consisting of multiple outer balloons located radially outward of the inner balloon A and circumferentially z-directly of the inner balloon A. By expanding both the inner balloon A and the balloon group B, the outer diameter of the balloon 2 can be increased. As a result, the stenotic portion can be reliably expanded.

[0039] As shown in Figure 3, when the inner balloon A and balloon group B of the balloon catheter 1 are expanded, it is preferable that adjacent outer balloons b1 and b2 among the multiple outer balloons constituting the balloon group B 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 balloon group B. In addition, when adjacent outer balloons b1 and b2 are in contact with each other, even if balloon group B comes into contact with the stenosis, it is 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.

[0040] When the inner balloon A and balloon group B are expanded, the multiple outer balloons constituting balloon group B only need to have at least one pair of adjacent outer balloons in contact with each other, preferably two or more pairs of adjacent outer balloons in contact with each other, and more preferably all adjacent outer balloons in contact with each other. When all adjacent outer balloons are in contact with each other, the outer balloons can be expanded uniformly.

[0041] When the inner balloon A and balloon group B are expanded, the outer balloons constituting balloon group B do not need to be in contact with the outer surface of the inner balloon A, but it is preferable that at least one of the multiple outer balloons constituting balloon group B is in contact with the outer surface of the inner balloon A. Because at least one of the multiple outer balloons is in contact with the outer surface of the inner balloon A, even if the outer balloon is pressed against the constricted area, the outer balloon remains in contact with the outer surface of the inner balloon A, making it less likely for the outer balloon to shift in the radial direction y of the inner balloon A, and ensuring that the constricted area is reliably expanded. It is even more preferable that all of the multiple outer balloons constituting balloon group B are in contact with the outer surface of the inner balloon A. Because all of the multiple outer balloons are in contact with the outer surface of the inner balloon A, even if the outer balloon is pressed against the constricted area, the inner balloon A and the outer balloons expand against each other, thus enabling balloon group B to withstand high pressure.

[0042] The number of outer balloons constituting balloon group 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 constituting balloon group B within the above range, balloon group B can more easily surround the outer circumference of inner balloon A, and balloon group B can more easily suppress the expansion of inner balloon A. As a result, when fluid is introduced into both inner balloon A and balloon group B, inner balloon A and outer balloons suppress each other's expansion, thereby increasing the pressure resistance of balloon 2, increasing the hardness of balloon 2, and improving its expansion force. Furthermore, because inner balloon A and outer balloons suppress each other's expansion, balloon 2 becomes less likely to inflate, so even if high pressure is applied to balloon 2, over-expansion of balloon 2 is suppressed, preventing balloon 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 constituting balloon group B, but for example, 20 or less is preferred, 12 or less is more preferred, 10 or less is even more preferred, and 8 or less is particularly preferred. By setting the upper limit of the number of outer balloons constituting balloon group B within the above range, the outer balloons constituting balloon group B become less likely to shift radially (y) and circumferentially (z) relative to inner balloon A, making it easier for balloon group B to suppress the expansion of inner balloon A.

[0043] When the inner balloon A and balloon group B are expanded, the maximum outer diameter of the circumscribed circle of balloon 2 is not particularly limited, but is preferably in the range of 5 mm to 60 mm.

[0044] The relationship between the maximum outer diameter of the inner balloon A and the maximum outer diameter of the outer balloons constituting the balloon group B is preferably any one of the following (1) to (3), for example. (1) When the inner balloon A and the balloon group B are expanded, all of the maximum outer diameters of the outer balloons constituting the balloon group B are the same, and the maximum outer diameter of the outer balloons is the same as the maximum outer diameter of the inner balloon A. (2) When the balloon group B is expanded, there are two or more types of outer balloons constituting the balloon group B that have different maximum outer diameters. (3) When the inner balloon A and the balloon group B are expanded, all of the maximum outer diameters of the outer balloons constituting the balloon group B are the same, and the maximum outer diameter of the outer balloons is different from the maximum outer diameter of the inner balloon A.

[0045] The maximum outer diameter of the inner balloon A refers to the maximum equivalent circle diameter of the inner balloon A in a cross section perpendicular to the longitudinal direction x of the inner balloon A. The maximum outer diameter of the outer balloon refers to the maximum equivalent circle diameter of the outer balloon in a cross section perpendicular to the longitudinal direction x of the outer balloon.

[0046] Item (1) will be described with reference to FIG. 3. As shown in FIG. 3, when the inner balloon A and the balloon group B are expanded, all of the maximum outer diameters of the outer balloons constituting the balloon group B are the same, and the maximum outer diameter of the outer balloons is the same as the maximum outer diameter of the inner balloon A. This makes it easy to achieve a balance between the force by which the inner balloon A attempts to expand and the force by which the expansion of the outer balloon attempts to suppress the expansion of the inner balloon A. As a result, the hardness of the inner balloon A and the balloon group B increases, the expansion force of the balloon group B can be easily increased, and the stenotic lesion can be uniformly expanded.

[0047] When the maximum outer diameter of the inner balloon A and all outer balloons is the same, the maximum outer diameter of the inner balloon A and the outer balloons is preferably, for example, 3 mm to 8 mm. The fact that all of the maximum outer diameters of the plurality of outer balloons constituting the balloon group B are the same means that the maximum outer diameters of the plurality of outer balloons constituting the balloon group B are substantially equal. Specifically, with respect to the maximum outer diameter of the outer balloon having the smallest maximum outer diameter among the outer balloons constituting the balloon group B, the maximum outer diameter of the outer balloon having the largest maximum outer diameter among the outer balloons constituting the balloon group B is 100% or more and 110% or less. The fact that the maximum outer diameter of the inner balloon A is the same as the maximum outer diameter of the plurality of outer balloons constituting the balloon group B means that the maximum outer diameter of the inner balloon A and the maximum outer diameter of the plurality of outer balloons constituting the balloon group B are substantially equal. Specifically, it means that the maximum outer diameter of the inner balloon A is 90% or more and 110% or less of the maximum outer diameter (for example, the average value) of the outer balloons.

[0048] Item (2) will be described with reference to FIG. 5. As shown in FIG. 5, when the balloon group B is expanded, since the outer balloons constituting the balloon group B are of two or more types having different maximum outer diameters, a plurality of outer balloons having different maximum outer diameters are arranged in the circumferential direction z around the outer periphery of the inner balloon A. Therefore, among the balloon group B, the outer balloons b11 and b12 having a large maximum outer diameter come into contact with the inner wall of the blood vessel, and the outer balloons b13 and b14 having a small maximum outer diameter do not contact the inner wall of the blood vessel. As a result, a space is easily formed between the inner wall of the blood vessel and the outer balloons b13 and b14 that are not in contact with the inner wall of the blood vessel, allowing blood to perfuse. In addition, since the outer balloons b11 and b12 having a large maximum outer diameter in the balloon group B contact the inner wall of the blood vessel, the number of outer balloons in the balloon group B that contact the inner wall of the blood vessel is limited to a part. This reduces the number of contact points between the outer balloons and the inner wall of the blood vessel, allowing the stress applied from the outer balloons to the inner wall of the blood vessel to be concentrated. As a result, the stenotic lesion can be reliably expanded.

[0049] As shown in Figure 5, when balloon group B consists of at least three outer balloons, and when inner balloon A and balloon group B are expanded, two types of outer balloons with different maximum outer diameters are arranged in the circumferential direction z radially outward from inner balloon A, 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 in the circumferential direction z radially outward from 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 inner balloon A, thereby enabling stable blood perfusion.

[0050] When balloon group B is expanded, the maximum outer diameter of the multiple outer balloons constituting balloon group 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 diameter of the outer balloons constituting balloon group B be two different sizes.

[0051] As shown in Figure 5, when the inner balloon A and balloon group B are expanded, if there are two types of outer balloons constituting balloon group 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.

[0052] As shown in Figure 5, when the inner balloon A and balloon group B are expanded, if there are two types of outer balloons constituting balloon group 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).

[0053] (3) will be explained using Figure 6. As shown in Figure 6, when the inner balloon A and balloon group B are expanded, the maximum outer diameters of the multiple outer balloons constituting balloon group B are all the same, but the maximum outer diameter of the outer balloons is different from the maximum outer diameter of the inner balloon A. This makes it easier to adjust the maximum outer diameter of balloon group B by appropriately combining and adjusting the inner balloon A and the outer balloons which have different maximum outer diameters. The fact that the maximum outer diameters of the multiple outer balloons constituting balloon group B are all the same means that the maximum outer diameters of the multiple outer balloons constituting balloon group B are approximately the same. Specifically, this means that the maximum outer diameter of the outer balloon with the largest maximum outer diameter among the outer balloons constituting balloon group B is between 100% and 110% of the maximum outer diameter of the outer balloon with the smallest maximum outer diameter among the outer balloons constituting balloon group B.

[0054] In case (3), when the inner balloon A and balloon group B are expanded, the maximum outer diameter of the multiple outer balloons constituting balloon group 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 making the maximum outer diameter of the multiple outer balloons constituting balloon group B smaller than the maximum outer diameter of the inner balloon A, the inner balloon A can be expanded at high pressure, thereby ensuring that the constricted area is expanded.

[0055] When the maximum outer diameter of the multiple outer balloons constituting balloon group 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.

[0056] When the maximum outer diameter of the multiple outer balloons constituting balloon group 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).

[0057] When the maximum outer diameter of the multiple outer balloons constituting balloon group B is smaller than the maximum outer diameter of inner balloon A, the ratio of the maximum outer diameter Db21 of the outer balloon 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.

[0058] When the maximum outer diameter of the multiple outer balloons constituting balloon group 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.

[0059] Examples of materials that make up the inner balloon A and the outer balloon 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.

[0060] For the materials constituting the inner balloon A and the outer balloon, 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. 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, 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.

[0061] The materials constituting the inner balloon A and the outer balloon 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 is greater than the pressure resistance value P1 of the inner balloon A. By using a flexible material for the inner balloon A and a high-pressure resistant material for the outer balloon, the balloon shape during expansion can be stabilized, and constricted areas can be expanded under high pressure. The materials constituting multiple outer balloons 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 can be made to be of a similar degree.

[0062] 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 as 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 improves the insertion of the balloon catheter 1 into the blood vessel.

[0063] 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 at 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 2.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] A tip member 60 may be provided at the distal end of the balloon catheter 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 inner balloon A.

[0069] 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.

[0070] This application claims the benefit of priority based on Japanese Patent Application No. 2025-057072, filed on 28 March 2025. The entire contents of the specification of the above Japanese Patent Application No. 2025-057072 are incorporated herein by reference.

[0071] 1 Balloon catheter 2 Balloon 5 Hub 6 Fluid injection section 10 Shaft 15 Distal shaft 16 Proximal shaft 21 Proximal sleeve section 22 Proximal tapered section 22p Proximal end of proximal tapered section 23 Straight section 23d Distal end of straight section (proximal end of distal tapered section) 23p Proximal end of straight section (distal end of proximal tapered section) 24 Distal tapered section 24d Distal end of distal tapered section 25 Distal sleeve section 50 Guidewire port 60 Tip component 70 Marker 71 First marker 72 Second marker 73 Third marker A Inner balloon B Balloon group 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 the outer balloon x Longitudinal direction y Radial direction z Circumferential direction AL Length in the longitudinal direction from the proximal end of the proximal tapered section of the inner balloon to the distal end of the distal tapered section BL Length in the longitudinal direction from the proximal end of the proximal tapered section of the outer balloon to the distal end of the distal tapered section ALe Length in the longitudinal direction of the straight section of the inner balloon BLE Length in the longitudinal direction of the straight section of the outer balloon ALp1 Length in the longitudinal direction of the proximal tapered section of the inner balloon ALp2 Length in the radial direction of the proximal tapered section of the inner balloon BLp1 Length in the longitudinal direction of the proximal tapered section of the outer balloon BLp2 Length in the radial direction of the proximal tapered section of the outer balloon ALd1 Length in the longitudinal direction of the distal tapered section of the inner balloon ALd2: Radial length of the distal tapered portion of the inner balloon. BLd1: Longitudinal length of the distal tapered portion of the outer balloon. BLd2: Radial length of the distal tapered portion of the outer balloon.

Claims

1. A balloon catheter comprising: a shaft extending longitudinally from proximal to distal; an inner balloon disposed at the distal end of the shaft; a balloon group consisting of a plurality of outer balloons arranged radially outward from the inner balloon and aligned circumferentially with the inner balloon; and a first marker and a second marker disposed outside the shaft and inside the inner balloon, wherein the inner balloon and the outer balloon 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 proximal end of the proximal tapered section of the inner balloon being distal to the proximal end of the proximal tapered section of the outer balloon and proximal to the distal end of the proximal tapered section of the outer balloon, A balloon catheter wherein the distal end of the distal tapered portion of the inner balloon is located proximal to the distal end of the distal tapered portion of the outer balloon and distal to the proximal end of the distal tapered portion of the outer balloon, the first marker is located on the portion of the shaft located in the proximal tapered portion of the inner balloon, and the second marker is located on the portion of the shaft located in the distal tapered portion of the inner balloon.

2. The balloon catheter according to claim 1, wherein the distal end of the first marker is located distal to the proximal end of the straight portion of the outer balloon, and the proximal end of the second marker is located proximal to the distal end of the straight portion of the outer balloon.

3. 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.

4. 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.

5. The balloon catheter according to claim 1 or 2, further comprising a third marker disposed outside the shaft and inside the inner balloon, wherein the third marker is disposed on the portion of the shaft located in the straight tubular portion of the inner balloon.

6. The balloon catheter according to claim 5, wherein the third marker is located on the portion of the shaft that is positioned at the midpoint of the length in the longitudinal direction of the straight tube 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, at least one of the plurality of outer balloons constituting the balloon group is in contact with the outer surface of the inner balloon.

9. 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.

10. 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.

11. The balloon catheter according to claim 10, wherein, when the inner balloon and the balloon group are expanded, two types of 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.

12. 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.

13. The balloon catheter according to claim 12, 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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