Balloon catheter

Abstract

Provided is a balloon catheter having a first balloon, a second balloon, a first inflation tube having a lumen communicating with a lumen of the first balloon, and a second inflation tube having a lumen communicating with a lumen of the second balloon, wherein kink is less likely to occur even when the balloon catheter is inserted into a bent part of a blood vessel.　This balloon catheter comprises a shaft, a first balloon, a second balloon, a first inflation tube, and a second inflation tube. The lumen of the first inflation tube communicates with the lumen of the shaft and the lumen of the first balloon. The lumen of the second inflation tube communicates with the lumen of the shaft and the lumen of the second balloon. The shaft has a first section on the distal side in which the first and second inflation tubes are disposed, and a second section which is closer to the proximal side than the first section and in which the first and second inflation tubes are disposed. In the first section, at least two of the shaft, the first inflation tube, and the second inflation tube are fixed to each other. In the second section, the shaft, the first inflation tube, and the second inflation tube are not fixed to each other.

Description

Balloon catheter

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

[0002] The formation of hardened stenotic areas due to calcification and other factors on the inner walls of blood vessels can lead to diseases such as angina pectoris and myocardial infarction. One of the treatment methods for these conditions is angioplasty, which uses a balloon catheter to dilate the stenotic 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 chest surgery like bypass surgery, and is widely performed.

[0003] A balloon catheter used in angioplasty includes at least a shaft extending longitudinally from the proximal side to the distal side, a balloon disposed at the distal portion of the shaft, and an inflation tube communicating with the balloon and through which a fluid for inflating or deflating the balloon can flow. The balloon is inserted into a blood vessel in a deflated state and delivered through the blood vessel to the stenotic site. After the balloon is delivered to the stenotic site, an indeflator (balloon pressurizer) connected to the inflation tube is used to introduce or expel fluid into or from the inflation tube to control the inflation and deflation of the balloon. An example of such a balloon catheter is described in Patent Document 1. Figure 42 of Patent Document 1 shows a dilation device including an inner balloon member and multiple outer balloon members, and Figure 43A shows the outer balloon members in an expanded state.

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

[0005] The balloon catheter described in Patent Document 1 includes an inner balloon member and multiple outer balloon members, and is provided with inflation lumens corresponding to the inner balloon member and the multiple outer balloon members so that the inner balloon member and the multiple outer balloon members can be inflated at different times. However, the rigidity of the region where the multiple inflation lumens are located is higher than the rigidity of the region where the multiple inflation lumens are not located, resulting in a large difference in rigidity in the longitudinal direction. For example, when the balloon catheter is inserted through a bent portion of a blood vessel, kinking occurs between the section where the multiple inflation lumens are located and the section where the multiple inflation lumens are not located.

[0006] The present invention was made in consideration of the above circumstances, and its purpose is to provide a balloon catheter having a first balloon, a second balloon, a first inflation tube having an inner lumen communicating with the inner lumen of the first balloon, and a second inflation tube having an inner lumen communicating with the inner lumen of the second balloon, which is less likely to kink even when inserted into a bent portion of a blood vessel.

[0007] The present invention is as follows: [1] A balloon catheter comprising: a shaft extending longitudinally from a proximal side to a distal side, a first balloon and a second balloon disposed in a distal portion of the shaft, and a first inflation tube and a second inflation tube disposed in a lumen of the shaft, wherein the lumen of the first inflation tube communicates with the lumen of the shaft and the lumen of the first balloon, and the lumen of the second inflation tube communicates with the lumen of the shaft and the lumen of the second balloon, the shaft having a first section on the distal side in which the first inflation tube and the second inflation tube are disposed, and a second section proximal to the first section in which the first inflation tube and the second inflation tube are disposed, wherein at least two of the shaft, the first inflation tube, and the second inflation tube are fixed to each other in the first section, and the shaft, the first inflation tube, and the second inflation tube are not fixed to each other in the second section. [2] The balloon catheter according to [1], wherein the length W2 of the second section in the longitudinal direction is longer than the length W1 of the first section in the longitudinal direction. [3] The balloon catheter according to [2], wherein the ratio (W2 / W1) of the length W2 of the second section in the longitudinal direction to the length W1 of the first section in the longitudinal direction is 1.1 to 2. [4] The balloon catheter according to any one of [1] to [3], wherein a guidewire tube through which a guidewire is inserted is further disposed in the lumen of the shaft, and a portion of the guidewire tube is disposed in the lumen of the first balloon. [5] The balloon catheter according to any one of [1] to [4], wherein a hole is disposed in the sidewall of the first inflation tube in the second section, allowing the lumen of the first inflation tube to communicate with the lumen of the shaft. [6] The balloon catheter according to any one of [1] to [5], wherein a plurality of second balloons are present, and the plurality of second balloons are arranged circumferentially around the outer periphery of the first balloon.[7] The balloon catheter according to [6], wherein there are a plurality of second inflation tubes, and a hole is provided in the side wall of the first inflation tube in the second section, which connects the lumen of the first inflation tube with the lumen of the shaft, or a hole is provided in the side wall of a plurality of second inflation tubes in the second section, which connects the lumen of the second inflation tube with the lumen of the shaft.

[0008] The balloon catheter of the present invention has a section in the lumen of the shaft where the first inflation tube and the second inflation tube are disposed, and this section includes a section in which at least two of the shaft, the first inflation tube, and the second inflation tube are fixed to one another, and a section in which the shaft, the first inflation tube, and the second inflation tube are not fixed to one another. The existence of these two sections reduces the difference in rigidity along the length of the shaft, making it less likely to kink when the balloon catheter of the present invention is inserted through a bent portion of a blood vessel.

[0009] FIG. 1 is a side view (partially perspective) of a balloon catheter. FIG. 2 is a longitudinal cross-sectional view of a shaft constituting the balloon catheter. FIG. 3 is a longitudinal cross-sectional view of another shaft constituting the balloon catheter. FIG. 4 is a longitudinal cross-sectional view of another shaft constituting the balloon catheter. FIG. 5 is a side view (partially perspective) of a balloon of the balloon catheter. FIG. 6 is a cross-sectional view of line I-I of the balloon shown in FIG. 5. FIG. 7 is a cross-sectional view of a balloon different from the balloon shown in FIG. 5. FIG. 8 is a cross-sectional view of a balloon different from the balloon shown in FIG. 5.

[0010] The balloon catheter of the present invention comprises a shaft extending longitudinally from the proximal side to the distal side, a first balloon and a second balloon disposed in a distal portion of the shaft, and a first inflation tube and a second inflation tube disposed in an inner lumen of the shaft, the inner lumen of the first inflation tube communicating with the inner lumen of the shaft and the inner lumen of the first balloon, and the inner lumen of the second inflation tube communicating with the inner lumen of the shaft and the inner lumen of the second balloon, the shaft having a first section on the distal side in which the first inflation tube and the second inflation tube are disposed, and a second section located proximal to the first section in which the first inflation tube and the second inflation tube are disposed, the gist of the balloon catheter being that at least two of the shaft, the first inflation tube, and the second inflation tube are fixed to each other in the first section, and the shaft, the first inflation tube, and the second inflation tube are not fixed to each other in the second section.

[0011] The following describes in detail balloon catheters according to embodiments of the present invention with reference to the drawings. However, the present invention is not limited to the illustrated examples, and modifications may be made within the scope of the above-mentioned and below-mentioned spirit, and all such modifications are within the technical scope of the present invention. For convenience, hatching and symbols may be omitted in the drawings. In such cases, reference should be made to the specification and other drawings. Furthermore, the dimensions of various components in the drawings may differ from their actual dimensions, as priority is given to aiding understanding of the features of the present invention.

[0012] Fig. 1 is a side view (partially perspective view) of a balloon catheter according to an embodiment of the present invention. Fig. 2 is a longitudinal cross-sectional view of a shaft constituting the balloon catheter according to an embodiment of the present invention. In Figs. 1 and 2, the left side of the figure is the proximal side (operator side), and the right side is the distal side (affected area side). The same applies to Figs. 3 to 5 below.

[0013] 1, a balloon catheter 1 according to an embodiment of the present invention has a shaft 10 extending longitudinally from the proximal side to the distal side, and a first balloon A and a second balloon B disposed in the distal portion of the shaft 10. In this specification, the first balloon A and the second balloon B may be collectively referred to as "balloon 2."

[0014] The number of first balloons A and the number of second balloons B may be one each. In this case, the first balloon A and the second balloon B may be arranged side by side at the same position in the longitudinal direction, or may be arranged side by side on the distal side and the proximal side in the longitudinal direction. When arranged side by side on the distal side and the proximal side, the first balloon A may be arranged on the distal side and the second balloon B on the proximal side, or the first balloon A may be arranged on the proximal side and the second balloon B on the distal side.

[0015] It is preferable that there be a plurality of second balloons B, and more preferably, as shown in Figure 1, a plurality of second balloons B are arranged in a line in the circumferential direction around the outer periphery of the first balloon A. In this specification, a plurality of second balloons B may be referred to as a "balloon group."

[0016] 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 side opposite the proximal side, i.e., the direction toward the treatment subject, is referred to as the distal side.

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

[0018] The first balloon A and the second balloon B are connected to the distal portion of the shaft 10. The first balloon A and the second balloon B can be expanded by introducing a fluid through the lumen of the shaft 10, and can be deflated by discharging the introduced fluid. To control the expansion and contraction of the first balloon A and the second balloon B, an indeflator (balloon pressurizer) can be used to introduce or discharge the fluid. For example, a mixture of a contrast agent and physiological saline is used as the fluid. The fluid may also be a pressurized fluid pressurized by a pump or the like.

[0019] As shown in Figure 2, the balloon catheter 1 has a first inflation tube 31 and a second inflation tube 32 (32b1, 32b2) disposed within the lumen of the shaft 10. The number of first inflation tubes 31 may be the same as the number of first balloons A, and the number of second inflation tubes 32 may be the same as the number of second balloons B. In Figure 2, one first inflation tube 31 and two second inflation tubes 32b1, 32b2 are shown within the lumen of the shaft 10. The first inflation tube 31 has a lumen L31, the second inflation tube 32b1 has a lumen L32b1, and the second inflation tube 32b2 has a lumen L32b2.

[0020] As shown in Figure 2, the shaft 10 of the balloon catheter 1 may further include a guidewire tube 40 extending in the longitudinal direction x and having a guidewire inserted through the lumen L31 of the first inflation tube 31. The guidewire tube 40 has a guidewire lumen L40. It is preferable that a portion of the guidewire tube 40 is disposed in the lumen of the first balloon A. While Figure 2 shows an example of a coaxial structure in which the guidewire tube 40 is disposed in the lumen L31 of the first inflation tube 31, the guidewire tube 40 and the first inflation tube 31 may also be disposed in a biaxial configuration.

[0021] The lumen L31 of the first inflation tube 31 is in communication with the lumen L10 of the shaft 10 and the lumen of the first balloon A (not shown). The lumen L32 (L32b1, L32b2) of the second inflation tube 32 (32b1, 32b2) is in communication with the lumen L10 of the shaft 10 and the lumen of the second balloon B (not shown). It is preferable that the first inflation tube 31 and the first balloon A are directly connected. It is preferable that the second inflation tubes 32 (32b1, 32b2) are each directly connected to the second balloon B (not shown).

[0022] The shaft 10 has a distal first section in which the first inflation tube 31 and the second inflation tube 32 are disposed, and a second section located proximal to the first section in which the first inflation tube 31 and the second inflation tube 32 are disposed. In the first section, at least two of the shaft 10, the first inflation tube 31, and the second inflation tube 32 are fixed to each other, while in the second section, the shaft 10, the first inflation tube 31, and the second inflation tube 32 are not fixed to each other. Because the shaft 10, the first inflation tube 31, and the second inflation tube 32 are not fixed to each other in the second section, the rigidity of the second section is less than that of the first section. Therefore, by disposing the second section proximal to the first section, the difference in rigidity can be reduced, making it less likely for kinking to occur even when the balloon catheter 1 is inserted through a bent portion of a blood vessel. That is, by providing the second section in the shaft 10, the second section acts as a cushion and prevents kinking, regardless of the bending force applied from any direction in the radial direction y of the shaft 10. Furthermore, when a pulling force is applied to the shaft 10 and the first and second sections are pulled, the portion of the first section adjacent to the second section stretches. Even in this case, the shaft 10, the first inflation tube 31, and the second inflation tube 32 are not fixed to each other in the second section, so the first inflation tube 31 and the second inflation tube 32 do not stretch. As a result, the inner lumens of the first inflation tube 31 and the second inflation tube 32 can be prevented from collapsing. Furthermore, if, for example, a guidewire tube 40 is further arranged in the inner cavity L10 of the shaft 10, even if the guidewire inserted through the guidewire tube 40 comes into contact with a narrowed area or the like and the force from the operator is concentrated in one place, and the guidewire is pressed from the inside to the outside of the guidewire tube 40, the existence of the second section acts as a cushion, preventing the guidewire tube 40 from kinking.

[0023] 2, in the first section, the shaft 10 and the second inflation tube 31 are fixed to each other, and the first inflation tube 31 and the second inflation tube 32 are fixed to each other. If there is only one first inflation tube 31 and one second inflation tube 32, it is sufficient that the shaft 10 and the first inflation tube 31, the shaft 10 and the second inflation tube 32, and the first inflation tube 31 and the second inflation tube 32 are fixed to each other.

[0024] The length W1 of the first section in the longitudinal direction x is, for example, preferably 8 to 20 mm, more preferably 9 mm or more, even more preferably 10 mm or more, and more preferably 19 mm or less, and even more preferably 18 mm or less. The length W2 of the second section in the longitudinal direction x is, for example, preferably 15 to 25 mm, more preferably 16 mm or more, even more preferably 17 mm or more, and more preferably 24 mm or less, and even more preferably 23 mm or less.

[0025] The length W2 of the second section in the longitudinal direction x may be shorter than the length W1 of the first section in the longitudinal direction x (W2<W1) or may be the same as the length W1 of the first section in the longitudinal direction x (W2=W1), but is preferably longer than the length W1 of the first section in the longitudinal direction x (W2>W1). When the length W2 of the second section in the longitudinal direction x is longer than the length W1 of the first section, the difference in rigidity between the sections where the first inflation tube 31 and the second inflation tube 32 are arranged is reduced, making it even less likely that kinking will occur when the balloon catheter 1 is inserted into a blood vessel.

[0026] When the length W2 of the second section in the longitudinal direction x is longer than the length W1 of the first section in the longitudinal direction x (W2 > W1), the ratio (W2 / W1) of the length W2 of the second section in the longitudinal direction x to the length W1 of the first section in the longitudinal direction x is preferably, for example, 1.1 to 2. When the ratio (W2 / W1) satisfies this range, the difference in rigidity is reduced, making it even less likely that kinking will occur when the balloon catheter 1 is inserted into a blood vessel. The ratio (W2 / W1) is more preferably 1.2 or greater, even more preferably 1.3 or greater, and more preferably 1.9 or less, even more preferably 1.8 or less.

[0027] As shown in FIG. 3 , the balloon catheter 1 may have holes h1-hn, which communicate between the lumen of the first inflation tube 31 and the lumen L10 of the shaft 10, arranged in the sidewall of the first inflation tube 31 in the second section. n represents a positive integer. Of the holes h1-hn, hole h1 is the hole arranged most proximal in the longitudinal direction x, and hole hn is the hole arranged most distal in the longitudinal direction x. When holes h1-hn, which communicate between the lumen of the first inflation tube 31 and the lumen L10 of the shaft 10, are arranged in the sidewall of the first inflation tube 31 in the second section as shown in FIG. 3 , it is preferable that the first inflation tube 31 be fixed to the shaft 10 proximal to the most proximal position of hole h1, which is the most proximal hole in the longitudinal direction x, among the holes arranged in the sidewall of the first inflation tube 31. The fixed position is referred to as fixed position x1. By introducing fluid into the first inflation tube 31, the fluid is introduced into the lumen of the first balloon A through the lumen L31 of the first inflation tube 31. At this time, a portion of the fluid flows out into the lumen L10 of the shaft 10 through the holes h1-hn arranged in the sidewall of the first inflation tube 31. The outflowing fluid accumulates in the lumen L10 of the shaft 10, and the accumulated fluid is introduced into the second balloon B through the lumen L32 (L32b1, L32b2) of the second inflation tube 32 (32b1, 32b2). By introducing fluid into the first inflation tube 31 in this manner, the order in which the first balloon A and the second balloon B are inflated can be controlled. As a result, when the first balloon A and the second balloon B are positioned at the affected area and inflated, there is a period of time between the inflation of the first balloon A and the inflation of the second balloon B, which allows fine adjustment of the positions of the first balloon A and the second balloon B and facilitates positioning of the balloon 2. Furthermore, by inflating the second balloon B later than the first balloon A, the amount of blood perfusion can be maintained even while the positions of the first balloon A and the second balloon B are being finely adjusted.

[0028] 3 , the first inflation tube 31 may extend to the proximal end so that the shaft 10 covers the outside of the first inflation tube 31, or alternatively, only the first inflation tube 31 may extend to the proximal end, with the inner surface of the proximal end of the shaft 10 fixed to the outer surface of the first inflation tube 31 and the shaft 10 positioned only distal to the fixed position x1 between the first inflation tube 31 and the shaft 10, or alternatively, only the shaft 10 may extend to the proximal end, with the outer surface of the proximal end of the first inflation tube 31 fixed to the inner surface of the shaft 10 and the first inflation tube 31 positioned only distal to the fixed position x1 between the first inflation tube 31 and the shaft 10. By extending only the first inflation tube 31 or the shaft 10 to the proximal end, the outer diameter of the balloon catheter 1 can be reduced, thereby improving minimally invasiveness. The first inflation tube 31 and the shaft 10 are preferably fixed together using an adhesive or by thermal welding, for example.

[0029] When second inflation tubes 32 (32b1, 32b2) are disposed in the lumen L10 of the shaft 10, the number of second inflation tubes 32 (32b1, 32b2) may be set according to the number of second balloons B. That is, although Fig. 3 shows an example of a configuration in which multiple second inflation tubes 32 are present in the lumen L10 of the shaft 10, when there is one second balloon B, only one second inflation tube 32 is required.

[0030] In the balloon catheter 1, when a plurality of second inflation tubes 32 are present in the lumen L10 of the shaft 10, the hole communicating the lumen L31 of the first inflation tube 31 with the lumen L10 of the shaft 10 may be disposed in the side wall of the first inflation tube 31 in the second section as described above, or, as shown in Figure 4, holes communicating the lumen L32 of the second inflation tube 32 with the lumen L10 of the shaft 10 may be disposed in the side walls of a plurality of second inflation tubes 32 in the second section. When a hole communicating the lumen L32 of the second inflation tube 32 with the lumen L10 of the shaft 10 is disposed in the side wall of the second inflation tube 32 in the second section, it is preferable that the second inflation tube 32 be fixed to the shaft 10 proximal to the most proximal position of the hole h1 disposed in the side wall of the second inflation tube 32, the most proximal hole in the longitudinal direction x. The fixed position is referred to as fixed position x1. By introducing fluid into the second inflation tube 32 (32b1, 32b2), the fluid is introduced into the lumen of the second balloon B through the lumen L32 (L32b1, L32b2) of the second inflation tube 32 (32b1, 32b2). At this time, a portion of the fluid flows out into the lumen L10 of the shaft 10 through holes h1-hn arranged in the side wall of the second inflation tube 32 (32b1, 32b2). The outflowing fluid accumulates in the lumen L10 of the shaft 10, and the accumulated fluid is introduced into the first balloon A through the lumen L31 of the first inflation tube 31. By introducing fluid into the second inflation tube 32 in this manner, the order in which the first balloon A and the second balloon B are inflated can be controlled. As a result, the first balloon A expands later than the second balloon B, causing the first balloon A to push out the multiple second balloons B that have expanded earlier in the radial direction y, thereby increasing the adhesion between the second balloon B and the inner wall of the blood vessel.

[0031] 4 , the second inflation tube 32 may extend to the proximal end so that the shaft 10 covers the outside of the second inflation tube 32, or alternatively, only the second inflation tube 32 may extend to the proximal end, the inner surface of the proximal end of the shaft 10 may be fixed to the outer surface of the second inflation tube 32, and the shaft 10 may be positioned only distal to the fixed position x1 between the second inflation tube 32 and the shaft 10, or only the shaft 10 may extend to the proximal end, the outer surface of the proximal end of the second inflation tube 32 may be fixed to the inner surface of the shaft 10, and the second inflation tube 32 may be positioned only distal to the fixed position x1 between the second inflation tube 32 and the shaft 10. By extending only the second inflation tube 32 or the shaft 10 to the proximal end, the outer diameter of the balloon catheter 1 can be reduced, thereby improving minimally invasiveness. The second inflation tube 32 and the shaft 10 are preferably fixed together using an adhesive or by heat welding, for example.

[0032] When holes connecting the inner cavity L32 of the second inflation tube 32 with the inner cavity L10 of the shaft 10 are arranged in the side walls of the plurality of second inflation tubes 32 in the second section, as shown in FIG. 4, the holes may be formed in each of the plurality of second inflation tubes 32 (32b1, 32b2), or the holes may be formed in only one of the plurality of second inflation tubes 32.

[0033] The number of holes arranged in the side wall of the first inflation tube 31 or the second inflation tube 32 may be one or more, and the number of holes may be set appropriately based on, for example, the time difference between the inflation of the first balloon A and the inflation of the second balloon B. The number of holes is, for example, preferably five or more, and more preferably ten or more. The upper limit of the number of holes is, for example, preferably 40 or less, more preferably 35 or less, and even more preferably 30 or less.

[0034] The holes in the sidewall of the first inflation tube 31 or the second inflation tube 32 are preferably positioned so that the fluid introduced into the first inflation tube 31 or the second inflation tube 32 is discharged evenly from the inside to the outside in the radial direction y of the first inflation tube 31 or the second inflation tube 32. Specifically, the holes may be arranged side by side in the longitudinal direction x, or may be arranged spirally relative to the longitudinal direction x, or may be arranged randomly.

[0035] The size of the hole formed in the side wall of the first inflation tube 31 or the second inflation tube 32 may be set appropriately based on, for example, the time difference between when the first balloon A and the second balloon B are inflated.

[0036] As shown in Figures 2 to 4, the shaft 10 of the balloon catheter 1 may further include a guidewire tube 40 extending in the longitudinal direction x and through which a guidewire is inserted. When the guidewire tube 40 is included, as shown in Figure 3, the first inflation tube 31 and the second inflation tube 32 are preferably disposed around the outer periphery of the guidewire tube 40. This allows the first inflation tube 31 and the second inflation tube 32 to support the guidewire tube 40, thereby preventing damage to the guidewire tube 40. As shown in Figures 2 and 4, a portion of the guidewire tube 40 is preferably disposed in the lumen L31 of the first inflation tube 31. Disposing a portion of the guidewire tube 40 in the lumen L31 of the first inflation tube 31 improves the operability of the balloon catheter 1. A portion of the guidewire tube 40 is preferably disposed in the lumen of the first balloon A. This further prevents damage to the guidewire tube 40. The guidewire tube 40 may be arranged in a biaxial structure in the lumen L10 of the shaft 10, running parallel to the first inflation tube 31, as shown in Figure 3, or in a coaxial structure in the lumen L31 of the first inflation tube 31, as shown in Figures 2 and 4.

[0037] Examples of materials that can be used to form the shaft 10 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluorine-based resins, vinyl chloride resins, silicone resins, and natural rubber. These materials can be used alone or in combination. Among these, the material that can form the shaft 10 is preferably at least one selected from polyamide resins, polyolefin resins, and fluorine-based resins. The use of polyamide resins, polyolefin resins, or fluorine-based resins increases the slipperiness of the surface of the shaft 10, thereby improving the ease of insertion of the balloon catheter 1 into a blood vessel.

[0038] Examples of materials constituting the first inflation tube 31, the second inflation tube 32, and the guidewire tube 40 include polyamide-based resins, polyester-based resins, polyurethane-based resins, polyolefin-based resins, fluorine-based resins, vinyl chloride-based resins, silicone-based resins, and natural rubber. These materials may be used alone or in combination. Among these, at least one selected from polyamide-based resins, polyolefin-based resins, and fluorine-based resins is preferred. The materials constituting the first inflation tube 31, the second inflation tube 32, and the guidewire tube 40 may be different, but are preferably the same. Using the same material can ensure uniform rigidity.

[0039] 1, the balloon catheter 1 preferably has a plurality of second balloons B arranged side by side in the circumferential direction z around the outer periphery of the first balloon A. The arrangement of the first balloon A and the second balloon B will be described with reference to FIG.

[0040] FIG. 5 is a side view (partially perspective view) of the balloon of the balloon catheter 1. FIG. 5 shows a state in which a balloon group consisting of a first balloon A and multiple second balloons B is inflated. FIG. 6 is a cross-sectional view of the balloon 2 shown in FIG. 5 taken along line I-I. The balloon catheter 1 shown in FIGS. 5 and 6 is composed of one first balloon A and six second balloons B, and the six second balloons B make up a balloon group. For ease of explanation, in FIGS. 5 and 6, two of the six second balloons B are labeled b1 and b2. When the first balloon A and the second balloon B (b1, b2) are inflated, the maximum outer diameter of the first balloon A is Da, and the maximum outer diameters of the second balloons b1 and b2 are Db1 and Db2, respectively.

[0041] 5 and 6, the balloon catheter 1 has a balloon group consisting of multiple second balloons B arranged around the outer periphery of the first balloon A in the circumferential direction z, and by inflating both the first balloon A and the balloon group, the outer diameter of the balloon 2 can be increased, thereby ensuring reliable dilation of the stenotic area.

[0042] 5 and 6, in the balloon catheter 1, it is preferable that, when the first balloon A and the balloon group are inflated, adjacent second balloons b1 and b2 of the multiple second balloons B constituting the balloon group are in contact with each other. By having adjacent second balloons b1 and b2 in contact with each other, the second balloons suppress each other's expansion, thereby increasing the pressure resistance and enhancing the inflation force of the balloon group. Furthermore, by having adjacent second balloons b1 and b2 in contact with each other, even if the second balloon B comes into contact with the stenosis, it is less likely to shift in the circumferential direction z around the outer periphery of the first balloon A, thereby ensuring reliable inflation of the stenosis.

[0043] During inflation of the first balloon A and the balloon group, it is sufficient that at least one pair of adjacent second balloons B constituting the balloon group are in contact with each other, preferably two or more pairs of adjacent second balloons B are in contact with each other, and more preferably all adjacent second balloons are in contact with each other. By having all adjacent second balloons B in contact with each other, the second balloons B can be inflated uniformly.

[0044] During inflation of the first balloon A and the balloon group, the second balloon B constituting the balloon group may not be in contact with the outer circumferential surface of the first balloon A. However, it is preferable that at least one of the multiple second balloons B constituting the balloon group be in contact with the outer circumferential surface of the first balloon A. By having at least one of the multiple second balloons B in contact with the outer circumferential surface of the first balloon A, even when the second balloon B is pressed against the narrowed portion, the second balloon B is in contact with the outer circumferential surface of the first balloon A, making it less likely for the first balloon A to shift in the radial direction y, thereby ensuring reliable inflation of the narrowed portion. It is more preferable that all of the multiple second balloons B constituting the balloon group be in contact with the outer circumferential surface of the first balloon A. By having all of the multiple second balloons B in contact with the outer circumferential surface of the first balloon A, even when the second balloon B is pressed against the narrowed portion, the first balloon A and the second balloon B will mutually inflate, thereby enabling the balloon group to withstand high pressure.

[0045] The number of second balloons B constituting the balloon group 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 second balloons B constituting the balloon group within the above range, the balloon group can easily surround the outer periphery of the first balloon A, making it easier for the balloon group to suppress the expansion of the first balloon A. As a result, when fluid is introduced into both the first balloon A and the balloon group, the first balloon A and the second balloon B mutually suppress the expansion of each other, making the balloon 2 more pressure-resistant and increasing the hardness of the balloon 2, thereby improving the expansion force. Furthermore, the first balloon A and the second balloon B mutually suppress the expansion of each other, making the balloon 2 less likely to expand. Therefore, even when high pressure is applied to the balloon 2, over-expansion of the balloon 2 is suppressed, preventing the balloon 2 from expanding beyond the intended outer diameter. This reduces damage to the aortic valve and other internal lumens, thereby improving safety. Although there is no particular upper limit to the number of second balloons constituting the balloon group, 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 to the number of second balloons B constituting the balloon group within the above range, the second balloons B constituting the balloon group are less likely to shift in the radial direction y and circumferential direction z of the first balloon A, making it easier for the balloon group to suppress the expansion of the first balloon A.

[0046] When the first balloon A and the balloon group are inflated, the maximum outer diameter of the circumscribed circle of the balloon 2 is not particularly limited, but is preferably in the range of 5 mm to 60 mm, for example.

[0047] The relationship between the maximum outer diameter of the first balloon A and the maximum outer diameter of the second balloon B constituting the balloon group preferably satisfies, for example, any of the following conditions (1) to (3): (1) When the first balloon A and the balloon group are inflated, the second balloons B constituting the balloon group all have the same maximum outer diameter, and the maximum outer diameter of the second balloon B is the same as the maximum outer diameter of the first balloon A. (2) When the balloon group is inflated, the second balloons B constituting the balloon group have two or more different maximum outer diameters. (3) When the first balloon A and the balloon group are inflated, the second balloons B constituting the balloon group all have the same maximum outer diameter, and the maximum outer diameter of the second balloon B is different from the maximum outer diameter of the first balloon A. The maximum outer diameter of the first balloon A refers to the maximum circle-equivalent diameter of the first balloon A in a cross section perpendicular to the longitudinal direction x of the first balloon A. The maximum outer diameter of the second balloon B refers to the maximum circle-equivalent diameter of the second balloon B in a cross section perpendicular to the longitudinal direction x of the second balloon B.

[0048] Item (1) will be explained using Figure 6. As shown in Figure 6, when the first balloon A and the balloon group are inflated, the second balloons B constituting the balloon group all have the same maximum outer diameter, and the maximum outer diameter of the second balloon B is the same as the maximum outer diameter of the first balloon A. This facilitates balancing the force exerted by the first balloon A to expand and the force exerted by the second balloon B to inhibit the expansion of the first balloon A. As a result, the hardness of the first balloon A and the balloon group is increased, making it easier to increase the expansion force of the balloon group and achieve uniform dilation of the stenotic area.

[0049] When the maximum outer diameters of the first balloon A and all of the second balloons B are the same, the maximum outer diameters of the first balloon A and the second balloons B are preferably, for example, 3 mm to 8 mm. The fact that the maximum outer diameters of the second balloons B constituting the balloon group are all the same means that the maximum outer diameters of the second balloons B constituting the balloon group are approximately the same. Specifically, this means that the maximum outer diameter of the second balloon B constituting the balloon group with the largest maximum outer diameter is 100% to 110% of the maximum outer diameter of the second balloon B with the smallest maximum outer diameter. The fact that the maximum outer diameter of the first balloon A is the same as the maximum outer diameters of the second balloons B constituting the balloon group means that the maximum outer diameter of the first balloon A and the maximum outer diameters of the second balloons B constituting the balloon group are approximately the same. Specifically, this means that the maximum outer diameter of the first balloon A is 90% to 110% of the maximum outer diameter (e.g., average value) of the second balloons B.

[0050] (2) will be described with reference to FIG. 7 . FIG. 7 is a cross-sectional view of a balloon different from the balloon shown in FIG. 5 , taken at a position corresponding to FIG. 6 . As shown in FIG. 7 , when the balloon group is inflated, the second balloons B constituting the balloon group are of two or more different maximum outer diameters. Therefore, multiple second balloons with different maximum outer diameters are arranged in the circumferential direction z around the outer periphery of the first balloon A. Therefore, the second balloons B (b11, b12) of the balloon group with the larger maximum outer diameter are in contact with the inner wall of the blood vessel, while the second balloons B (b13, b14) with the smaller maximum outer diameter are not in contact with the inner wall of the blood vessel. This makes it easier for a space to form between the inner wall of the blood vessel and the second balloons B (b13, b14) that are not in contact with the inner wall of the blood vessel, allowing blood to perfuse. Furthermore, the second balloon B (b11, b12) with the largest maximum outer diameter among the balloon group comes into contact with the inner wall of the blood vessel, thereby limiting the number of second balloons B in the balloon group that come into contact with the inner wall of the blood vessel, thereby reducing the number of contact points between the second balloon B and the inner wall of the blood vessel and concentrating the stress applied from the second balloon B to the inner wall of the blood vessel. As a result, the narrowed portion can be dilated reliably.

[0051] When the balloon group includes at least three second balloons, and when the first balloon A and the balloon group are inflated, two types of second balloons B with different maximum outer diameters are arranged in the circumferential direction z around the outer periphery of the first balloon A, it is preferable that the second balloon b13 with the smaller maximum outer diameter be sandwiched between the second balloons b11 and b12 with the larger maximum outer diameter, as shown in Figure 7. By sandwiching the second balloon b13 with the smaller maximum outer diameter between the second balloons b11 and b12 with the larger maximum outer diameters in the circumferential direction z around the outer periphery of the first balloon A, the spaces formed between the inner wall of the blood vessel and the second balloons B that do not contact the inner wall are dispersed in the circumferential direction z around the outer periphery of the first balloon A, thereby enabling stable blood perfusion.

[0052] During inflation of the balloon group, the second balloons B constituting the balloon group may have, for example, two, three, or four or more different maximum outer diameters. Of these, it is preferable that the second balloons B constituting the balloon group have two different maximum outer diameters.

[0053] As shown in FIG. 7 , when the first balloon A and the balloon group are inflated, if the second balloons B constituting the balloon group are of two different types with different maximum outer diameters, the ratio (Db11 / Db13) of the maximum outer diameter Db11 of the second balloon b11 with the larger maximum outer diameter to the maximum outer diameter Db13 of the second balloon b13 with the smaller maximum outer diameter is, for example, preferably greater than 1 and less than or equal to 5, more preferably 1.1 or greater, even more preferably greater than 1.1, particularly preferably 2 or greater, most preferably 2.5 or greater, and more preferably 4.5 or less, even more preferably 4 or less.

[0054] As shown in FIG. 7 , when the first balloon A and the balloon group are inflated, if the second balloons constituting the balloon group have two different maximum outer diameters, the maximum outer diameter Db13 of the second 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 second balloon b11 with the larger maximum outer diameter is preferably, for example, 3.1 mm to 25 mm (particularly, more than 3.3 mm and 25 mm or less).

[0055] (3) will be described with reference to FIG. 8 . FIG. 8 is a cross-sectional view of a balloon different from the balloon shown in FIG. 5 , taken at a position corresponding to FIG. 6 . As shown in FIG. 8 , when the first balloon A and the balloon group are inflated, the maximum outer diameters of the second balloons B constituting the balloon group are all the same. However, the maximum outer diameter of the second balloons B is different from the maximum outer diameter of the first balloon A. This allows for adjustment by appropriately combining first balloons A and second balloons B with different maximum outer diameters, making it easier to adjust the maximum outer diameter of the balloon group. Having the same maximum outer diameters of the second balloons B constituting the balloon group means that the maximum outer diameters of the second balloons B constituting the balloon group are approximately the same. Specifically, this means that the maximum outer diameter of the second balloon B with the largest maximum outer diameter among the second balloons B constituting the balloon group is 100% or more but 110% or less of the maximum outer diameter of the second balloon B with the smallest maximum outer diameter among the second balloons B constituting the balloon group.

[0056] In the case of (3), when the first balloon A and the balloon group are inflated, the maximum outer diameter of the second balloons B constituting the balloon group may be larger or smaller than the maximum outer diameter of the first balloon A, but is preferably smaller. By having the maximum outer diameter of the second balloons B constituting the balloon group smaller than the maximum outer diameter of the first balloon A, the first balloon A can be inflated at a high pressure, thereby reliably dilating the stenotic area.

[0057] When the maximum outer diameter of the multiple second balloons B that make up the balloon group is larger than the maximum outer diameter of the first balloon A, the ratio of the maximum outer diameter Db21 of the second balloon b21 to the maximum outer diameter Da of the first balloon A (Db21 / Da) is, for example, preferably greater than 1 and less than 4.5, more preferably 1.1 or greater, even more preferably greater than 1.1, particularly preferably 1.2 or greater, and more preferably 4 or less, even more preferably 3 or less.

[0058] When the maximum outer diameter of the second balloons B constituting the balloon group is larger than the maximum outer diameter of the first balloon A, it is preferable that the maximum outer diameter Da of the first balloon A is, for example, 3 mm to 5 mm, and the maximum outer diameter Db21 of the second balloon b21 is, for example, 3.1 mm to 13.5 mm (particularly, more than 3.3 mm and 13.5 mm or less).

[0059] When the maximum outer diameter of the second balloons B constituting the balloon group is smaller than the maximum outer diameter of the first balloon A, the ratio of the maximum outer diameter Db21 of the second balloon B to the maximum outer diameter Da of the first balloon A (Db21 / Da) is, for example, preferably 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.

[0060] When the maximum outer diameter of the second balloons B constituting the balloon group is smaller than the maximum outer diameter of the first balloon A, it is preferable that the maximum outer diameter Da of the first balloon A is, for example, 3 mm to 20 mm, and the maximum outer diameter Db21 of the second balloon b21 is, for example, 1.0 mm to 5 mm.

[0061] As shown in FIG. 5 , the first balloon A and the second balloon B of the balloon catheter 1 preferably have 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, and 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.

[0062] During inflation of the first balloon A and the balloon group, the length L1 from the distal end Ad of the first balloon A to the proximal end Ap of the first balloon A in the longitudinal direction x may be the same as the length L2 from the distal end b1d of the second balloon b1 to the proximal end b1p of the second balloon b1 in the longitudinal direction x, but is preferably shorter. By making the length L1 of the first balloon A shorter than the length L2 of the second balloon b1, the portion where the first balloon A is present is more likely to be inflated to a greater extent than the portion where the first balloon A is not present. As a result, it is easier to apply pressure to the portion where the first balloon A is present, allowing for accurate application of pressure to the target location. Furthermore, since the portion where the first balloon A is not present is less likely to be inflated to a greater extent and therefore less likely to apply pressure, stress is less likely to be applied to portions other than the target location, thereby improving the minimally invasive nature of the balloon catheter 1.

[0063] When the first balloon A and the balloon group are inflated, the length L1 from the distal end Ad of the first balloon A to the proximal end Ap of the first 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 L2 from the distal end b1d of the second balloon b1 to the proximal end b1p of the second balloon b1 in the longitudinal direction x. By setting the upper limit of the ratio of the length L1 of the first balloon A to the length L2 of the second balloon b1 within the above range, the balloon catheter 1 can be made to easily apply high pressure accurately to the target location. Furthermore, during inflation of the first balloon A and the balloon group, the length L1 from the distal end Ad of the first balloon A to the proximal end Ap of the first balloon A in the longitudinal direction x is preferably at least 20%, more preferably at least 25%, and even more preferably at least 30% of the length L2 from the distal end b1d of the second balloon b1 to the proximal end b1p of the second balloon b1 in the longitudinal direction x. By setting the lower limit of the ratio of the length L1 of the first balloon A to the length L2 of the second balloon b1 within the above range, it becomes easier to apply pressure to a sufficient area of ​​the target site using the balloon catheter 1, making it easier to dilate a stenotic area or destroy a biological valve, for example.

[0064] 1, the balloon catheter 1 may be a so-called rapid exchange type balloon catheter, which has a guidewire port 50 midway from the distal side to the proximal side of the shaft 10 and a guidewire insertion passage from the guidewire port 50 to the distal side of the shaft 10. As shown in FIG. 1, the balloon catheter 1 has a hub 5 on the proximal side, and the hub 5 is provided with a fluid injection section 6 for injecting a fluid to inflate or deflate the balloon 2.

[0065] 1, the shaft 10 of the balloon catheter 1 preferably has a distal shaft 15 and a proximal shaft 16 disposed proximally of the distal shaft 15, and the distal shaft 15 and the proximal shaft 16 may be separate members. When the distal shaft 15 and the proximal shaft 16 are separate members, the proximal shaft 16 may be made of resin or metal.

[0066] In the case of a rapid exchange balloon catheter such as that shown in FIG. 1 , a coating is preferably applied to the outer wall of the proximal shaft 16 and / or the distal shaft 15, and more preferably to both the proximal shaft 16 and the distal shaft 15. The coating can be a hydrophilic or hydrophobic coating 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 coating the outer wall of the shaft 10 with a hydrophilic or hydrophobic coating agent. The coating agent may contain a drug or additive.

[0067] 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), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), silicone oil, hydrophobic urethane resin, carbon coat, diamond coat, diamond-like carbon (DLC) coat, ceramic coat, and substances terminated with alkyl groups or perfluoroalkyl groups and having low surface free energy.

[0068] Although not shown, the balloon catheter 1 may be a so-called over-the-wire balloon catheter having a guidewire passage extending from the distal to the proximal side of the shaft. In the case of an over-the-wire balloon catheter, the inflation lumen and the guidewire lumen extend to the hub 5 located at the proximal side, and the proximal openings of each lumen are preferably provided in the bifurcated hub 5. In the case of an over-the-wire balloon catheter, it is preferable that the outer wall of the outer shaft is coated. For details about the material and coating constituting the shaft, please refer to the description of the rapid exchange balloon catheter.

[0069] Examples of materials constituting the first balloon A and the second balloon B include polyolefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester-based resins such as polyethylene terephthalate and polyester elastomer; polyurethane-based resins such as polyurethane and polyurethane elastomer; polyphenylene sulfide-based resins; polyamide-based resins such as polyamide and polyamide elastomer; fluorine-based resins; silicone-based resins; and natural rubbers such as latex rubber. These materials may be used alone or in combination of two or more. Among these, the material constituting the first balloon A and the second balloon B is preferably at least one selected from polyamide-based resins, polyester-based resins, and polyurethane-based resins.

[0070] The materials constituting the first balloon A and the second balloon B are preferably elastomer resins in terms of thinness and flexibility. For example, among polyamide resins, nylon 12, nylon 11, etc. are suitable as the materials constituting the first balloon A and the second balloon B. Nylon 12 is more suitable because it can be relatively easily molded during blow molding. Furthermore, polyamide elastomers such as polyether ester amide elastomers and polyamide ether elastomers are preferred in terms of thinness and flexibility of the first balloon A and the second balloon B. Among these, polyether ester amide elastomers are preferred in terms of high yield strength and good dimensional stability of the first balloon A and the second balloon B.

[0071] The material constituting the first balloon A and the material constituting the second balloon B may be the same, but preferably they are different, and it is preferable to select a material such that the pressure resistance value P2 of the second balloon B is greater than the pressure resistance value P1 of the first balloon A. The materials constituting the multiple second balloons B may be different, but preferably they are the same. By using the same material, the degree of expansion and hardness of each second balloon B can be made to be approximately the same.

[0072] The shaft 10 disposed inside the first balloon A may have a radiopaque marker 70 disposed at the portion where the first balloon A is located in the longitudinal direction x so that the position of the first balloon A can be confirmed under X-ray fluoroscopy. The radiopaque marker 70 is preferably disposed at positions corresponding to both ends of the straight tube portion 23 of the first balloon A, or may be disposed at a position corresponding to the center of the straight tube portion 23 of the first balloon A. The shape of the radiopaque marker 70 is preferably tubular, and examples include a cylindrical shape, a polygonal cylindrical shape, a C-shaped cross-section with a notch in the tube, and a coil shape formed by winding a wire. The radiopaque marker 70 can be formed from a radiopaque substance such as lead, barium, iodine, tungsten, gold, platinum, iridium, stainless steel, titanium, or a cobalt-chromium alloy.

[0073] A tip member 60 is preferably 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 as a separate member from the shaft 10 and connected to the distal end of the first balloon A, or the distal end of the shaft 10 may function as the tip member 60 by extending distally beyond the distal end of the first balloon A.

[0074] 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 biological valve placed in the heart, or destroy the biological valve. Vascular stenosis can also occur in the aortic valve. When aortic valve stenosis occurs, the aortic valve is removed and a new biological valve is implanted. However, implanted biological valves deteriorate over time and need to be replaced every 5 to 10 years. When a surgically implanted biological valve (artificial valve) deteriorates and a new biological valve (artificial valve) is placed via a catheter, the valve orifice area may become smaller. Therefore, the size of the new biological valve must be smaller than the deteriorated biological valve, which reduces blood flow, creates a pressure gradient across the biological valve, and places a strain on the heart. Therefore, by using the balloon catheter 1 to deform or destroy a biological valve placed in the heart, a larger biological valve can be implanted, thereby reducing the pressure gradient across the biological valve.

[0075] The method for manufacturing the balloon catheter 1 is not particularly limited, and may involve, for example, inserting the first inflation tube 31, the second inflation tube 32, and, if necessary, the guidewire tube 40 into the lumen L10 of the shaft 10 and securing them with an adhesive or by thermal welding. In this case, a second section in which the shaft 10, the first inflation tube 31, and the second inflation tube 32 are not secured to one another is formed proximal to a first section in which at least two of the shaft 10, the first inflation tube 31, and the second inflation tube 32 are secured to one another.

[0076] This application claims the benefit of priority based on Japanese Patent Application No. 2023-102824, filed on June 22, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-102824 are incorporated herein by reference.

[0077] REFERENCE SIGNS LIST 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 23 straight tube section 24 distal tapered section 25 distal sleeve section 31 first inflation tube 32, 32b1, 32b2 second inflation tube 40 guidewire tube 50 guidewire port 60 distal tip member 70 radiopaque marker 90 boundary line between distal shaft 15 and proximal shaft 16 A first balloon B second balloon b1, b2, b11 to b14, b21 to b23 second balloon Da maximum outer diameter of first balloon Db1, Db2, Db11 to Db14, Db21 to Db23 maximum outer diameter of second balloon h1 to hn Hole L10: Shaft lumen L31: First inflation tube lumen L32, L32b1, L32b2: Second inflation tube lumen L40: Guidewire lumen W1: Length of first section in the longitudinal direction W2: Length of second section in the longitudinal direction x: Longitudinal direction x1: Fixing position y: Radial direction z: Circumferential direction

Claims

1. A balloon catheter having a shaft extending longitudinally from a proximal side to a distal side, a first balloon and a second balloon disposed in a distal portion of the shaft, and a first inflation tube and a second inflation tube disposed in an inner lumen of the shaft, wherein the inner lumen of the first inflation tube is connected to the inner lumen of the shaft and to the inner lumen of the first balloon, and the inner lumen of the second inflation tube is connected to the inner lumen of the shaft and to the inner lumen of the second balloon, the shaft having a first section on the distal side in which the first inflation tube and the second inflation tube are disposed, and a second section proximal to the first section in which the first inflation tube and the second inflation tube are disposed, wherein at least two of the shaft, the first inflation tube, and the second inflation tube are fixed to each other in the first section, and wherein the shaft, the first inflation tube, and the second inflation tube are not fixed to each other in the second section.

2. The balloon catheter according to claim 1, wherein the length W2 of the second section in the longitudinal direction is longer than the length W1 of the first section in the longitudinal direction.

3. The balloon catheter according to claim 2, wherein the ratio (W2 / W1) of the length W2 of said second section in the longitudinal direction to the length W1 of said first section in the longitudinal direction is 1.1 to 2.

4. The balloon catheter according to claim 1, further comprising a guidewire tube through which a guidewire is inserted, the guidewire tube being disposed in the inner cavity of the shaft, and a portion of the guidewire tube being disposed in the inner cavity of the first balloon.

5. A balloon catheter as claimed in claim 1, wherein a hole is provided in the side wall of said first inflation tube in said second section, providing communication between the inner lumen of said first inflation tube and the inner lumen of said shaft.

6. The balloon catheter according to claim 1, wherein there are a plurality of said second balloons, and the plurality of said second balloons are arranged in a line in the circumferential direction around the outer periphery of said first balloon.

7. A balloon catheter as described in claim 6, wherein there are a plurality of second inflation tubes, and a side wall of the first inflation tube in the second section has a hole communicating the inner lumen of the first inflation tube with the inner lumen of the shaft, or a plurality of side walls of the second inflation tubes in the second section have holes communicating the inner lumen of the second inflation tube with the inner lumen of the shaft.

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