Balloon catheter

Abstract

A balloon catheter comprising: a catheter shaft 18; a balloon 20 provided to the distal side portion of the catheter shaft 18; and a heating member 22 capable of heating a fluid inside the balloon 20, wherein, in the inside of the balloon 20, a fluid chamber 50 to which the fluid for expanding the balloon 20 is supplied is formed at an outer part of the catheter shaft 18, and the catheter shaft 18 is provided with an outer shaft 54, an inner shaft 56 that is inserted inside the outer shaft 54 and that penetrates at least an expansion part of the balloon 20, and a volume reduction member 58 that reduces the volume of the fluid chamber 50.

Description

Balloon catheter

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

[0002] Patent Document 1 discloses a balloon catheter including a catheter shaft, a balloon provided at a distal portion of the catheter shaft, and a heating member capable of heating fluid inside the balloon.

[0003] Japanese Patent Application Laid-Open No. 2003-116904

[0004] When heating the fluid inside the balloon by the heating member, it is desired to reduce temperature unevenness of the fluid inside the balloon as much as possible.

[0005] Therefore, one object of the present disclosure is to provide a balloon catheter that can be advantageous for reducing temperature unevenness of fluid when the fluid inside the balloon is heated.

[0006] The balloon catheter of the present disclosure includes: a catheter shaft; a balloon provided at a distal portion of the catheter shaft, the balloon having an expansion section expandable by fluid supplied into an interior thereof; and a heating member capable of heating fluid inside the balloon, wherein a fluid chamber to which fluid for expanding the balloon is supplied is formed outside the catheter shaft inside the balloon, and the catheter shaft includes: an outer shaft; an inner shaft inserted through the outer shaft and passing through at least the expansion section of the balloon; and a volume reducing member disposed distal to the outer shaft to reduce the volume of the fluid chamber.

[0007] According to the present disclosure, it can be advantageous for reducing temperature unevenness of fluid when the fluid inside the balloon is heated.

[0008] It is a schematic diagram showing the balloon catheter of the embodiment. It is a cross-sectional view showing a part of the balloon catheter of the embodiment. It is a perspective view showing the balloon of the embodiment. It is a IV-IV cross-sectional view of FIG. 2. It is an explanatory diagram relating to the fluid chamber of the embodiment. It is an enlarged view of FIG. 2. It is a VII-VII cross-sectional view of FIG. 6.

[0009] Embodiments for implementing the balloon catheter of this disclosure are described below. The same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for ease of explanation. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0010] Refer to Figures 1 and 2. The balloon catheter 10 is used for procedures on living organs. In this embodiment, it is used for ablation. In this case, the balloon catheter 10 is used by heating the fluid supplied into the balloon 20 with a heating element 22. By adjusting the temperature of the fluid inside the balloon 20 by heating with the heating element 22, the surface temperature of the balloon 20 is adjusted. Ablation is performed by bringing the balloon 20, whose surface temperature has been adjusted, into contact with living tissue. The specific living organs to be treated are not particularly limited and may include parts of the digestive system such as the bile duct and pancreatic duct, as well as parts of the circulatory system such as the heart and blood vessels.

[0011] The balloon catheter 10 comprises a catheter shaft 18, a balloon 20 provided on the distal portion of the catheter shaft 18, a heating member 22 capable of heating the fluid supplied into the balloon 20, and a handle device 24 provided on the proximal portion of the catheter shaft 18.

[0012] Refer to Figure 1. The handle device 24 may include a handle 30 grasped by the operator and first and second hubs 32A and 32B through which the catheter shaft 18 is inserted. The handle device 24 may also include a connector 38 for electrically connecting a power supply 34 and an information processing device 36. The handle device 24 may be provided with a wire port 40 for inserting a guide wire into the balloon catheter 10, a supply port 44 for supplying fluid from a fluid supply device 42 to inflate the balloon 20, and a discharge port 48 for discharging fluid to a fluid discharge device 46. The fluid supply device 42 and the fluid discharge device 46 are configured using an indeflater, syringe, pump, etc. Specific examples of the fluid for inflating the balloon 20 are not particularly limited and may include various liquids such as contrast agents, saline solution, and sterile water, as well as semi-solid materials such as gels.

[0013] Refer to Figures 2 and 3. Unless otherwise specified, the positional relationships of each component are described based on the case where the balloon 20 is in an expanded state and the catheter shaft 18 is extended in a straight line. Furthermore, the positional relationships of each component are described below with reference to the centerline C10 of the balloon catheter 10. The centerline C10 of the balloon catheter 10 refers to the centerline of the balloon 20 in an expanded state within the axial range where the balloon 20 is present, and to the centerline of the catheter shaft 18 within the axial range where the balloon 20 is not present. The direction along the centerline C10 of the balloon catheter 10 is simply called the axial direction, and the radial and circumferential directions relative to the centerline C10 are called the radial direction and circumferential direction. Also, one side in the axial direction is called the distal side, and the other side is called the proximal side.

[0014] The balloon 20 is expandable by fluid supplied from the proximal side of the catheter shaft 18. Figure 1 shows the balloon 20 in a deflated state, while Figure 2 and other figures show the balloon 20 in an expanded state. The balloon 20 may be made of various resin materials used for balloons, such as polyamide resin or polyurethane. The balloon 20 comprises an expandable portion 20a that can be expanded by fluid supplied inside, and sleeve portions 20b provided on both axial sides of the expandable portion 20a.

[0015] The balloon 20 in this embodiment is a cylindrical balloon. The expansion portion 20a of this balloon 20 comprises a pair of cone portions 20c provided at both axial ends of the expansion portion 20a, and a cylindrical portion 20d provided between the pair of cone portions 20c. The outer diameter of the cone portions 20c gradually increases as it moves toward the cylindrical portion 20d in the axial direction. The specific shape of the cone portions 20c is not particularly limited. The cone portions 20c may be constructed using at least one of a conical surface with a constant rate of change in outer diameter in the axial direction, and a curved surface with a rate of change in outer diameter that changes in the axial direction. In this embodiment, an example is shown in which the cone portions 20c are constructed using a single conical surface, but they may be constructed using a plurality of conical surfaces with different rates of change in outer diameter. The rate of change in outer diameter here refers to the rate at which the outer diameter changes per unit axial length. The cylindrical portion 20d connects the pair of cone portions 20c. The cylindrical portion 20d in this embodiment is cylindrical with a constant outer diameter in the axial direction. In addition, the cylindrical portion 20d may have a constant outer diameter change rate that is smaller than the outer diameter change rate of the cone portion 20c. Here, "constant" does not mean strictly constant, but also includes approximately constant.

[0016] The balloon 20 is not limited to a cylindrical balloon; a spherical balloon or the like may also be used. Each sleeve portion 20b is fixed to a part of the catheter shaft 18 by welding, adhesive, or the like. Here, an example is shown where the proximal sleeve portion 20b is fixed to the distal end of the outer shaft 54 ​​(described later), and the distal sleeve portion 20b is fixed to the distal portion of the volume-reducing member 58 (described later).

[0017] The balloon 20 comprises a main body portion 20e that forms a fluid chamber 50, which will be described later, and an insertion passage forming portion 20f that forms an insertion passage 52 between itself and the main body portion 20e, located radially outward from the main body portion 20e. The main body portion 20e constitutes an expansion portion 20a and a sleeve portion 20b of the balloon 20. In this embodiment, the insertion passage forming portion 20f is provided integrally with the main body portion 20e and is composed of a protruding portion 20g that extends radially outward from the main body portion 20e. The balloon 20 may also have a pair of insertion passages 52 formed in it, as in this embodiment. In this case, the balloon 20 has a pair of protruding portions 20g that form each of the pair of insertion passages 52. An opening 52a is formed at the axial end of the insertion passage 52.

[0018] Refer to Figure 2. The catheter shaft 18 is flexible and can be bent. The catheter shaft 18 is inserted into the body, at least in its distal portion. The catheter shaft 18 supports the balloon 20. To achieve this, at least the sleeve portion 20b on the proximal side of the balloon 20 is fixed to the catheter shaft 18. Alternatively, to achieve this, the sleeve portion 20b on the distal side of the balloon 20 may also be fixed to the catheter shaft 18.

[0019] The catheter shaft 18 comprises an outer shaft 54 ​​and an inner shaft 56 inserted into the first lumen 60 of the outer shaft 54. Each shaft 54, 56 is constructed from various resin materials such as polyolefin resin, fluororesin, polyamide, polyether block amide, and polyurethane.

[0020] The outer shaft 54 ​​extends proximally from a position that radially overlaps with at least a portion of the balloon 20. A handle device 24 is provided on the proximal portion of the outer shaft 54 ​​(see Figure 1).

[0021] The inner shaft 56 extends distally from the first lumen 60 of the outer shaft 54. The inner shaft 56 axially penetrates the proximal sleeve portion 20b of the balloon 20. The inner shaft 56 axially penetrates at least the interior of the expanded portion 20a of the balloon 20. Here, "at least" means that it is not necessary for the inner shaft 56 to axially penetrate the entire balloon 20. More specifically, the inner shaft 56 only needs to be positioned so as to radially overlap the distal sleeve portion 20b in at least a portion of it, and it is not necessary for it to axially penetrate the sleeve portion 20b as in this embodiment. For example, the distal end of the inner shaft 56 may be located proximal to the distal end of the distal sleeve portion 20b. A guide wire lumen 56a is formed in the inner shaft 56 for inserting a guide wire that is inserted from the wire port 40 of the handle device 24. The inner shaft 56 is not directly fixed to the outer shaft 54 ​​by adhesive, welding, etc.

[0022] The catheter shaft 18 is equipped with a volume-reducing member 58 that surrounds the inner shaft 56 from the outer circumference and reduces the volume of the fluid chamber 50 (described later) within the balloon 20. Here, "reducing the volume of the fluid chamber 50" means reducing the volume of the fluid chamber 50 when the volume-reducing member 58 is present compared to the volume of the fluid chamber 50 when the volume-reducing member 58 is not present. To achieve this, the volume-reducing member 58 is provided in at least a portion of a certain axial range of the balloon 20. Furthermore, the volume-reducing member 58 is positioned distal to the outer shaft 54.

[0023] The volume-reducing member 58 in this embodiment is composed of a cylindrical shaft member in which the inner shaft 56 is arranged inside. The material of this shaft member may be, for example, various resin-based materials similar to those used for the other shafts 54 and 56. The specific example of the volume-reducing member 58 is not particularly limited and may be composed of, for example, a tape member wrapped around the inner shaft 56. The volume-reducing member 58 excludes the wiring inserted into the lumen of the outer shaft 54, as well as the wiring connection members to which the wiring is electrically connected. The wiring referred to here is, for example, the sensor wiring 76b and the heating element wiring 94, which will be described later. The wiring connection members refer to the heating element 22, etc., as described above.

[0024] The volume-reducing member 58 has a shaft hole 58a through which the inner shaft 56 is inserted within the balloon 20. The center line C58a of the shaft hole 58a is positioned offset from the center line C60 of the first lumen 60 of the outer shaft 54. The volume-reducing member 58 is fixed to the inner shaft 56 by welding, adhesive, etc. The volume-reducing member 58 is not directly fixed to the outer shaft 54 ​​by adhesive, welding, etc.

[0025] The inner shaft 56 comprises a proximal insertion portion 56b that is inserted into the first lumen 60 of the outer shaft 54, a distal insertion portion 56c that is inserted into the shaft hole 58a of the volume reduction member 58, and a connecting portion 56d that connects the proximal insertion portion 56b and the distal insertion portion 56c. The center line (not shown) of the connecting portion 56d extends diagonally so as it moves distally in the axial direction, it approaches the center line (not shown) of the distal insertion portion 56c from the center line (not shown) of the proximal insertion portion 56b. The connecting portion 56d is provided by bending a part of the inner shaft 56. This connecting portion 56d allows the inner shaft 56 to be inserted inside the center line C60 of the first lumen 60 and the center line C58a of the shaft hole 58a, even if they are misaligned. In this embodiment, where the inner shaft 56 has a connection portion 56d, the condition of extending the catheter shaft 18 in a straight line, as described above, can be satisfied if the catheter shaft 18 extends in a straight line at locations other than the connection portion 56d.

[0026] Refer to Figure 4. At least one lumen 60, 62 is formed in the outer shaft 54. This lumen 60, 62 includes a first lumen 60 that is eccentric with respect to the center line C54 of the outer shaft 54, and a second lumen 62 that is provided on the opposite side of the eccentricity direction D of the first lumen 60. Here, eccentricity means that the center line C60 of the first lumen 60 is eccentric with respect to the center line C54 of the outer shaft 54. Here, the eccentricity direction D is the direction from the center line C54 of the outer shaft 54 ​​toward the center line C60 of the first lumen 60. Here, "center line C60 of the first lumen 60" means the geometric center of the shape formed by the inner circumferential surface that forms the lumen 60 in a cross section perpendicular to the axial direction.

[0027] One of the first lumen 60 and the second lumen 62 becomes a supply lumen 64 that supplies fluid into the balloon 20, and the other becomes a discharge lumen 66 through which the fluid discharged from the balloon 20 flows. In this embodiment, the first lumen 60 becomes the discharge lumen 66, and the second lumen 62 becomes the supply lumen 64. Fluid is supplied into the balloon 20 from the fluid supply device 42 via the supply port 44 of the handle device 24 and the supply lumen 64. From inside the balloon 20, the fluid is discharged to the fluid supply device 42 via the discharge lumen 66 and the discharge port 48 of the handle device 24.

[0028] Refer to Figure 2. The heating element 22 is placed inside the balloon 20. In this embodiment, the heating elements 22 are provided in pairs with space between them inside the balloon 20. The number of heating elements 22 is not particularly limited and may be one, three or more. The heating elements 22 may be cylindrical as in this embodiment, or they may be linear, etc. Here, "cylindrical" refers to a long, slender, hollow shape.

[0029] The heating member 22 may be fixed to the volume reduction member 58 as in this embodiment. This allows the heating member 22 to heat a wider area of ​​fluid outside the volume reduction member 58 within the fluid chamber 50 formed in the balloon 20, compared to the case where the heating member 22 is fixed to the inner shaft 56 within the volume reduction member 58, thereby effectively heating the fluid in the fluid chamber 50. The specific means for fixing the heating member 22 to the volume reduction member 58 are not particularly limited. In this embodiment, the heating member 22 is fixed by being embedded in the outer circumference of the volume reduction member 58. Other methods such as adhesive may also be used. The heating member 22 may also be embedded in the volume reduction member 58 by reducing its diameter through impact such as swaging. By embedding it in the volume reduction member 58, the difference in outer diameter between the outer circumference of the volume reduction member 58 adjacent to the heating member 22 on both axial sides and the heating member 22 can be reduced. This makes it difficult for the balloon 20 to get caught on the axial edge of the outer circumference of the heating member 22. From this perspective, the outer periphery of the heating member 22 may be provided flush with the outer periphery of the volume reduction member 58 that is adjacent to the heating member 22 in the axial direction, as in this embodiment.

[0030] The heating element 22 is electrically connected to the power supply 34 via heating element wiring 94 (see Figure 6), which will be described later, and a connector 38. The heating element 22 heats the fluid inside the balloon 20 with power supplied from the power supply 34 via the heating element wiring 94. In this embodiment, the heating element 22 is heated by a direct resistance heating method, but the heating method is not particularly limited, and an indirect resistance heating method, ultrasonic heating method, laser heating method, etc., may be used.

[0031] Refer to Figure 5. Inside the balloon 20, a fluid chamber 50 is formed outside the catheter shaft 18, to which fluid for expanding the balloon 20 is supplied. In Figure 5, the location of the fluid chamber 50 is indicated by hatching. The fluid chamber 50 is formed outside the catheter shaft 18, in a location surrounded by the catheter shaft 18, the balloon 20, and the heating member 22, where fluid can be supplied. The internal space of the catheter shaft 18 is not treated as part of the fluid chamber 50. This internal space of the catheter shaft 18 refers to, for example, the supply lumen 64 and part of the discharge lumen 66 of the outer shaft 54, which are located radially overlapping with the sleeve portion 20b on the proximal side of the balloon 20, as well as the internal space of the shaft hole 58a of the volume reduction member 58.

[0032] The effects of the balloon catheter 10 in relation to the features described so far will now be explained. The larger the volume of the fluid chamber 50 in the balloon 20, the larger the volume of fluid present in that fluid chamber 50. Consequently, when the fluid inside the balloon 20 is heated by the heating element 22, temperature unevenness of the fluid tends to increase. Here, the catheter shaft 18 of this embodiment is equipped with a volume-reducing member 58 that reduces the volume of the fluid chamber 50 inside the balloon 20. Therefore, compared to the case without the volume-reducing member 58, the volume of the fluid chamber 50 inside the balloon 20 can be reduced by the presence of the volume-reducing member 58. This allows for a moderate reduction in the volume of fluid present in the fluid chamber 50, which is advantageous in reducing temperature unevenness of the fluid inside the fluid chamber 50 heated by the heating element 22. By reducing this temperature unevenness of the fluid, the temperature unevenness of the surface temperature of the balloon 20 heated by the fluid inside the balloon 20 can be reduced. This is advantageous in uniformly ablating the target area of ​​biological tissue with the balloon 20. The larger the outer diameter of the volume-reducing member 58, the more effectively the effects described here can be obtained.

[0033] Other features of the balloon catheter 10 will now be described. The volume-reducing member 58 may be provided continuously in an axial range that includes both the expanded portion 20a and the distal sleeve portion 20b of the balloon 20, as in this embodiment. Alternatively, the volume-reducing member 58 may penetrate the distal sleeve portion 20b of the balloon 20 axially, as in this embodiment. From the viewpoint of reducing the volume of the fluid chamber 50 as much as possible, the volume-reducing member 58 may be provided in an axial range that includes more than half of the axial range that includes the expanded portion 20a of the balloon 20. From this viewpoint, the volume-reducing member 58 may be provided in the entire axial range that includes the expanded portion 20a, as in this embodiment. Also, from a similar viewpoint, the volume-reducing member 58 may be provided continuously in an axial range that includes both the expanded portion 20a and the proximal sleeve portion 20b of the balloon 20. Also, from a similar viewpoint, the volume-reducing member 58 may be provided in the entire axial range that includes the cylindrical portion 20d of the balloon 20. The volume-reducing member 58 surrounds the inner shaft 56 in the axial range mentioned herein. In either case, reducing the volume of the fluid chamber 50 is advantageous in reducing temperature variations in the fluid within the fluid chamber 50.

[0034] The volume of the fluid chamber 50 is examined when the predetermined maximum expansion pressure is applied inside the balloon 20. Here, the maximum expansion pressure (RBP: Rated Burst Pressure) refers to the limit pressure that the manufacturer has predetermined as statistically achievable for the balloon 20. The volume V0 (mm²) of the cylindrical portion 20d of the balloon 20 in this state is examined. ３ ) and the volume V1 (mm³) of the fluid chamber 50 in the axial range where the cylindrical portion 20d is located. ３ ) and the value V2 (mm²) obtained by subtracting volume V1 from volume V0. ３The following is considered. Volume V0 refers to the volume of area A surrounded by the inner circumferential surface of the cylindrical portion 20d that forms the fluid chamber 50, assuming that no other elements such as the catheter shaft 18 exist inside the balloon 20. Volume V1 refers to the volume of area B, outside the catheter shaft 18, surrounded by the cylindrical portion 20d of the balloon 20, the catheter shaft 18, and the heating member 22, within a certain axial range of the cylindrical portion 20d. Value V2 represents the volume of the area obtained by subtracting area B from area A (= V0 - V1).

[0035] The ratio of the value V2 to the volume V0 as a percentage is called the volume reduction rate R (%). The volume reduction rate R can be expressed as 100 × (V2 / V0) (= 100 × (V2 / (V1+V2))). The volume reduction rate R indicates the degree to which the volume of the cylindrical portion 20d of the balloon 20 has decreased due to the catheter shaft 18 and the heating member 22. The larger the volume reduction rate R, the smaller the proportion occupied by the fluid chamber 50 within the cylindrical portion 20d. Consequently, the volume of fluid present in the fluid chamber 50 can be reduced, which is advantageous in reducing temperature unevenness of the fluid inside the balloon 20 when heated by the heating member 22.

[0036] From the viewpoint of reducing temperature unevenness in the fluid, the volume reduction rate R is preferably 10% or more, more preferably 13% or more, and even more preferably 15% or more. When the volume reduction member 58 is absent and the catheter shaft 18 consists only of the outer shaft 54 ​​and the inner shaft 56, the volume reduction rate R is usually 9.9% or less. Here, it is specified as a preferred condition to have a volume reduction rate R greater than the range that can normally be taken when the volume reduction member 58 is not used (≤9.9%). By incorporating the volume reduction member 58 into the catheter shaft 18, the volume reduction rate R can be easily increased to achieve this preferred condition. The larger the outer diameter of the volume reduction member 58, the greater the volume reduction rate R can be. The upper limit of the volume reduction rate R is not particularly limited, but it is preferably 35% or less, and more preferably 30% or less.

[0037] Let's consider the case where the volume reduction rate R is increased by increasing the outer diameter of the inner shaft 56, assuming that the volume reduction member 58 is absent. In this case, it becomes difficult to pass the inner shaft 56 through the first lumen 60 of the outer shaft 54, leading to a decrease in ease of assembly. In particular, if the wiring 76b and 94 are passed through the first lumen 60 of the outer shaft 54, it leads to a further decrease in ease of assembly. Because of this decrease in ease of assembly, if the volume reduction member 58 is absent, it is not usually conceivable to a person skilled in the art to increase the volume reduction rate R beyond the normal range (<9.9%) by increasing the outer diameter of the inner shaft 56. According to this embodiment, by incorporating the volume reduction member 58 into the catheter shaft 18, the volume reduction rate R can be increased beyond the normal range without increasing the outer diameter of the inner shaft 56. Therefore, it becomes easier to pass the inner shaft 56 through the first lumen 60 of the outer shaft 54, and there is also the advantage that good ease of assembly can be obtained while increasing the volume reduction rate R.

[0038] The larger the volume reduction rate R, the easier it becomes to design the balloon catheter 10 without using an agitator to suppress temperature unevenness of the fluid inside the balloon 20. The agitator consists of a pump such as a roller pump, diaphragm pump, or bellows pump. The agitator can agitate the fluid inside the balloon 20 by repeatedly discharging the fluid from inside the balloon 20 via the lumen of the catheter shaft 18 and supplying the discharged fluid back into the balloon 20. By not using an agitator, the configuration of the catheter system equipped with the balloon catheter 10 can be simplified, contributing to a reduction in the overall system cost.

[0039] Table 1 below shows an example of possible volume reduction rates R obtained under conditions where the outer diameter of the cylindrical portion 20d of the balloon 20 is changed, between a case where the volume reducing member 58 is not provided (No. A) and a case where the volume reducing member 58 is provided (No. B, No. C). In each example, the structure is common in all aspects other than the presence or absence of the volume reducing member 58, the outer diameter of the volume reducing member 58, and the outer diameter of the cylindrical portion 20d of the balloon 20. When the volume reducing member 58 is provided, the structure is as shown in Fig. 2. The case where the volume reducing member 58 is not provided means a case where only the inner shaft 56 is present within the cylindrical portion 20d of the balloon 20. Note that the outer diameters of the cylindrical portion 20d of the balloon 20 and the volume reducing member 58 described below are merely examples, and are not limited thereto.

[0040]

[0041] Next, other features of the balloon catheter 10 will be described. Reference is made to Fig. 6. A gap portion 70 is provided between the outer shaft 54 and the volume reducing member 58. The gap portion 70 is provided between the distally-facing end surface 54a of the outer shaft 54 and the proximally-facing end surface of the volume reducing member 58, which are opposed to each other in the axial direction. In the gap portion 70 of the present embodiment, a clearance 72 is formed between the outer shaft 54 and the volume reducing member 58. Alternatively, in the gap portion 70, the outer shaft 54 and the volume reducing member 58 may abut against each other without being fixed to each other.

[0042] Reference is made to Fig. 6 and Fig. 7. The balloon catheter 10 includes a linear member 74 provided in an axial range that straddles the gap portion 70 of the catheter shaft 18. In Fig. 6 and the like, the center line of the linear member 74 is mainly schematically illustrated. The linear member 74 has a linear shape as a whole. At least a part of the linear member 74 is disposed inside the balloon 20. In order to satisfy this condition, the linear member 74 of the present embodiment is inserted into the insertion passage 52 of the balloon 20. Alternatively, in order to satisfy this condition, the linear member 74 may be disposed inside the main body portion 20e of the balloon 20. The balloon catheter 10 of the present embodiment includes a total of two linear members 74, but the number thereof is not particularly limited, and may be one or three or more. The two linear members 74 are inserted into corresponding individual insertion passages 52, respectively.

[0043] The linear member 74 may be composed of a temperature sensor 76 for detecting the temperature of the balloon 20, as in this embodiment. The temperature sensor 76 in this embodiment is a thermocouple, but it may also be composed of a thermistor or the like. The temperature sensor 76 in this embodiment is located on the surface side of the main body 20e and detects the temperature of the surface side of the main body 20e as the temperature of the balloon 20. Alternatively, the temperature sensor 76 may be located inside the main body 20e and detect the temperature of the fluid supplied into the balloon 20 as the temperature of the balloon 20.

[0044] The temperature sensor 76 includes a signal detection unit 76a that detects an electrical signal indicating the temperature of the balloon 20, and a sensor wiring 76b that is electrically connected to the signal detection unit 76a. The signal detection unit 76a is provided at the distal end of the linear member 74, and the sensor wiring 76b constitutes the portion of the linear member 74 that is closer to the signal detection unit 76a. In this embodiment, a pair of sensor wirings 76b are electrically connected to one signal detection unit 76a. The sensor wiring 76b is electrically connected to a connector 38 via the first lumen 60 of the outer shaft 54, and then electrically connected to an information processing device 36 via the connector 38. The signal detection unit 76a outputs the detected electrical signal to the information processing device 36 via the sensor wiring 76b. The information processing device 36 can obtain a value indicating the temperature of the balloon 20 by performing various signal processing on the electrical signal detected by the signal detection unit 76a.

[0045] The outer diameter of the catheter shaft 18 will be discussed. Let R1 be the outer diameter of the outer shaft 54 at a portion continuous proximally with respect to the intermediate portion 70 of the catheter shaft 18, R2 be the outer diameter of the inner shaft 56 located at the intermediate portion 70, and R3 be the outer diameter of the volume reducing member 58 at a portion continuous distally with respect to the intermediate portion 70. These satisfy R1>R2 and R3>R2. In other words, from the proximal side toward the distal side, the outer diameter of the catheter shaft 18 changes in the pattern of large → small → large. In this case, at the intermediate portion 70 of the catheter shaft 18, the catheter shaft 18 becomes easily bendable. Therefore, when the linear member 74 is provided in an axial range straddling the intermediate portion 70 of the catheter shaft 18, there arises a problem that the catheter shaft 18 is likely to break together with the linear member 74 at the intermediate portion 70, that is, the entire balloon catheter 10 is likely to break.

[0046] As a countermeasure against this problem, the balloon catheter 10 may be provided with a reinforcing member 78 provided in an axial range straddling the intermediate portion 70 of the catheter shaft 18. The reinforcing member 78 has a role of reinforcing the bending rigidity of the balloon catheter 10 in the axial range straddling the intermediate portion 70. The reinforcing member 78 is formed of a material excellent in rigidity. As the material, for example, in addition to resin materials such as polyimide, polyamide and chlorinated plastic, metal materials such as stainless steel, NiTi and platinum iridium may be used.

[0047] The reinforcing member 78 may be composed of a linear body that is linear as a whole, as in this embodiment. The reinforcing member 78 may be composed of a tube member 80 in which the linear member 74 is arranged on the inside. This allows the bending of the linear member 74 to be restrained by the tube member 80, which is effective in suppressing such bending. Furthermore, by composing the reinforcing member 78 as a tube member 80, the space inside the tube member 80 can be utilized compared to when the reinforcing member 78 has a solid cross-section, increasing the design freedom when incorporating the reinforcing member 78. For example, it is possible to design a structure in which other members such as the linear member 74 are arranged inside the tube member 80. In addition, the reinforcing member 78 may be composed of a linear body with a solid cross-section. In this embodiment, multiple reinforcing members 78 are provided at positions spaced apart in the circumferential direction. Each reinforcing member 78 is provided individually corresponding to the linear member 74.

[0048] The reinforcing member 78 is inserted into the insertion passage 52 of the balloon 20 together with the linear member 74. The reinforcing member 78 is inserted into the insertion passage 52 of the balloon 20 in an axial range that spans the intercostal portion 70 of the catheter shaft 18, and is in contact with the balloon 20 in that axial range. The reinforcing member 78 may be provided at least in an axial range from the intercostal portion 70 of the catheter shaft 18 to the proximal cone portion 20c of the balloon 20, as in this embodiment. Alternatively, the reinforcing member 78 may be provided at least in an axial range from the intercostal portion 70 of the catheter shaft 18 to the proximal end of the balloon 20, as in this embodiment. In either case, the reinforcing member 78 may be in contact with the balloon 20 in the range in which it is provided in this manner. In this axial range in which the reinforcing member 78 is in contact with the balloon 20, the bending rigidity of the balloon 20 is reinforced.

[0049] Even if the catheter shaft 18 is prone to bending in the intermediate portion 70, the bending rigidity of the balloon catheter 10 can be reinforced by providing a reinforcing member 78 in the axial range spanning this intermediate portion 70. As a result, even in such cases, the entire balloon catheter 10 can be made less likely to break in the axial range spanning the intermediate portion 70, and the bending of the linear member 74 in that axial range can be suppressed. This is particularly effective in reducing the risk of disconnection due to bending of the sensor wiring 76b of the linear member 74.

[0050] Both the linear member 74 and the reinforcing member 78 are inserted through the opening 52a of the insertion passage 52 toward the rear. The distal end 74a of the linear member 74 is positioned within the insertion passage 52 of the balloon 20, beyond the end 78a of the reinforcing member 78, as viewed from the opening 52a of the insertion passage 52.

[0051] The linear member 74 is permitted to move relative to the catheter shaft 18 and the balloon 20 in the longitudinal direction. Furthermore, the linear member 74 is permitted to move relative to the tube member 80 that constitutes the reinforcing member 78 in the longitudinal direction. To achieve this, the linear member 74 is not fixed to the catheter shaft 18, balloon 20 and reinforcing member 78 by adhesive, welding, or the like.

[0052] When the balloon catheter 10 attempts to bend in the middle section 70 of the catheter shaft 18, the linear member 74 also attempts to bend along with the balloon 20. At this time, an axial force is applied to the linear member 74 as it bends, for example, by contacting a part of the insertion passage 52 of the balloon 20 as it bends together with the linear member 74. Let's consider the case where the linear member 74 is fixed to the balloon 20, etc. In this case, when an axial force is applied to the linear member 74 as the balloon catheter 10 bends, the linear member 74 becomes stiff at the point where it is fixed to the balloon 20, etc., making it easy for excessive force to be applied to the linear member 74. In this respect, according to the present embodiment, even if an axial force is applied to the linear member 74 as the balloon catheter 10 bends, the linear member 74 does not become stiff and can move relative to the balloon 20, etc. in the longitudinal direction. Consequently, the risk of breakage due to excessive force applied to the linear member 74 can be reduced.

[0053] The balloon catheter 10 includes a covering tube 86 that covers the catheter shaft 18 and forms an internal tube space 84 between the catheter shaft 18 and the covering tube 86. The covering tube 86 covers an axial range that straddles the boundary 88 between the balloon 20 and the catheter shaft 18. In this embodiment, the covering tube 86 covers an axial range that straddles the boundary 88 proximal to the balloon 20. The covering tube 86 is fixed to the balloon 20 by welding or the like on the balloon 20 side in the axial direction relative to the internal tube space 84. The covering tube 86 is also fixed to the catheter shaft 18 by welding or the like on the opposite side of the balloon 20 in the axial direction relative to the internal tube space 84. As a result, the internal tube space 84 is airtight with respect to the external space outside the balloon catheter 10. To make the internal tube space 84 airtight, the insertion passage 52 of the balloon 20 may be filled with adhesive or the like. This adhesive may, for example, be filled between the inner circumferential surface forming the insertion passage 52 and the tube member 80 at the opening 52a of the insertion passage 52 of the balloon 20.

[0054] The catheter shaft 18 has an insertion lumen 90 through which the linear member 74 is inserted, and an exit hole 92 for drawing the linear member 74 out from the inside of the catheter shaft 18 (insertion lumen 90) into the tube space 84. The insertion lumen 90 and the exit hole 92 are formed in the shaft that constitutes the catheter shaft 18, and in this embodiment they are formed in the outer shaft 54. The insertion lumen 90 may also be formed by the first lumen 60 of the outer shaft 54, as in this embodiment. In this embodiment, two linear members 74 (only one linear member 74 is shown in Figure 6) are drawn out to the outside through a common exit hole 92.

[0055] The reinforcing member 78 may be led out from the insertion passage 52 of the balloon 20 into the internal space 84 of the tube. Similar to the linear member 74, the reinforcing member 78 may be provided so as to be located within the insertion lumen 90 via an exit hole 92, in addition to being located in the insertion passage 52 of the balloon 20. In order to pass through these locations, the linear member 74 needs to be bent significantly while being routed. Consequently, when the linear member 74 moves relative to the balloon 20 in the longitudinal direction, the linear member 74 is prone to breaking at the points where it is sharply bent. Such bending of the linear member 74 can be restrained by the tube member 80 passing through the aforementioned locations, thereby suppressing the bending.

[0056] At least one (both in this embodiment) of the supply lumen 64 and the discharge lumen 66 opens to the distal end face 54a of the outer shaft 54. The gap 72 between the outer shaft 54 ​​and the volume reduction member 58 communicates with and opens to both the supply lumen 64 and the discharge lumen 66. When fluid is supplied to the fluid chamber 50, the fluid supplied from the supply lumen 64 flows through the gap 72 to a point in the fluid chamber 50 distal to the gap 72. When fluid is discharged from the fluid chamber 50, the fluid flows from a point in the fluid chamber 50 distal to the gap 72 through the gap 72 to the discharge lumen 66. The advantages of the above gap 72 will now be explained.

[0057] Prior to using the balloon catheter 10, an air-blowing operation is performed to remove air from the balloon 20 in order to reduce the amount of air bubbles inside the balloon 20 that cause temperature unevenness. The air-blowing operation is performed, for example, by supplying a fluid such as liquid into the fluid chamber 50 via the supply lumen 64 using the fluid supply device 42, while simultaneously discharging the air from the fluid chamber 50 via the discharge lumen 66 using the fluid discharge device 46. Let's consider the case where there is no gap 72 between the outer shaft 54 ​​and the volume reduction member 58. In this case, the lumens 64 and 66 that open to the distal end face 54a of the outer shaft 54 ​​are at least partially blocked by the volume reduction member 58. As a result, when the supply lumen 64 opens to the distal end face 54a, it becomes difficult to smoothly flow fluid from the supply lumen 64 into the fluid chamber 50. Also, when the discharge lumen 66 opens to the distal end face 54a, it becomes difficult to smoothly flow the air from the fluid chamber 50 to the discharge lumen 66.

[0058] In this respect, according to this embodiment, a gap 72 is formed between the outer shaft 54 ​​and the volume reduction member 58. Therefore, the lumens 64 and 66 that open to the distal end face 54a of the outer shaft 54 ​​are not blocked by the volume reduction member 58. As a result, when a supply lumen 64 opens to the distal end face 54a, it becomes easier to smoothly supply fluid from the supply lumen 64 into the fluid chamber 50 via the gap 72. Also, when a discharge lumen 66 opens to the distal end face 54a, it becomes easier to smoothly discharge air from the fluid chamber 50 into the discharge lumen 66 via the gap 72. In either case, during air bleeding, it becomes easier to smoothly supply fluid into the fluid chamber 50 or to smoothly discharge air from the fluid chamber 50, which is advantageous in reducing air bubbles in the fluid chamber 50 as much as possible.

[0059] The axial length of this gap 72 is not particularly limited. From the viewpoint of making the catheter shaft 18 less prone to breakage, the axial length of this gap 72 should be relatively small, for example, 0.05 mm to 1.0 mm, preferably 0.05 mm to 0.5 mm. With such an axial length, it becomes difficult to visually determine the presence of the gap 72. Even in this case, by applying a certain amount of pressure (for example, a pressure of 4 atm or more) to supply fluid from the supply lumen 64 into the fluid chamber 50, and discharging the fluid from the fluid chamber 50 through the discharge lumen 66, the fluid can flow smoothly between each lumen 64, 66 and the fluid chamber 50 via this gap 72.

[0060] To explain the advantages of this additional gap 72, a part of the manufacturing method of the balloon catheter 10 will be described. The manufacturing method of the balloon catheter 10 includes a temporary assembly step of temporarily assembling the catheter shaft 18, a balloon fixing step of fixing the balloon 20 to the volume reduction member 58 and the outer shaft 54 ​​of the temporarily assembled catheter shaft 18, a shaft fixing step of fixing the volume reduction member 58 and the inner shaft 56, and a tube fixing step of fixing the covering tube 86 to the balloon 20 and the catheter shaft 18 after the balloon fixing step.

[0061] The preliminary assembly process is performed by inserting the inner shaft 56 into the first lumen 60 of the outer shaft 54 ​​and also inserting the inner shaft 56 into the shaft hole 58a of the volume reduction member 58. When the catheter shaft 18 is in the preliminary assembly state, relative axial movement of the outer shaft 54, volume reduction member 58, and inner shaft 56 is permitted.

[0062] The balloon fixing process involves fixing the proximal sleeve portion 20b of the balloon 20 to the outer shaft 54 ​​by welding or the like, and fixing the distal sleeve portion 20b of the balloon 20 to the volume reduction member 58 by welding or the like. By fixing the balloon 20 to each outer shaft 54 ​​and 58 in this way, the relative axial position of each outer shaft 54 ​​and 58 is determined.

[0063] The shaft fixing process may be performed during the balloon fixing process by tightening the distal end of the balloon 20 and the volume reduction member 58 using a crimping tube, welding the balloon 20 to the volume reduction member 58, and simultaneously welding the volume reduction member 58 to the inner shaft 56. In other words, the shaft fixing process may be performed during the balloon fixing process. In addition, the shaft fixing process may be performed before or after the balloon fixing process.

[0064] In the manufacturing process of such a balloon catheter 10, if the aforementioned gap 72 exists, the relative axial position of the outer shaft 54 ​​and the volume reduction member 58 can be adjusted prior to the balloon fixing process. This makes it possible to adjust the axial dimension of the gap 72 and the axial position of the heating member 22 fixed to the volume reduction member 58.

[0065] In the manufacturing process of the balloon catheter 10, when it is in the stage prior to the tube fixing process, the catheter shaft 18 is not covered by the covering tube 86. In this embodiment, the reinforcing member 78 is drawn out from the insertion passage 52 of the balloon 20 into the tube space 84 of the covering tube 86. Therefore, when the catheter shaft 18 is not covered by the covering tube 86 as described above, there is an advantage in that the position of the reinforcing member 78 relative to the insertion passage 52 can be adjusted by grasping the point where the reinforcing member 78 is drawn out from the insertion passage 52 of the balloon 20.

[0066] The balloon catheter 10 is equipped with heating element wiring 94 that is electrically connected to the heating element 22. In Figure 6, only the centerline of most of the heating element wiring 94 is schematically shown. The heating element wiring 94 is provided corresponding to a plurality of heating elements 22. The volume reduction member 58 has side holes 58b formed at positions corresponding to the heating elements 22. The side holes 58b are formed to open on the inner circumferential surface of the shaft hole 58a of the volume reduction member 58 and expose the inner circumferential surface of the heating element 22. The distal end of the heating element wiring 94 is placed in the side hole 58b of the volume reduction member 58 and fixed to the inner circumferential surface of the heating element 22. To achieve this, the heating element wiring 94 may be fixed by soldering, adhesive, etc., or it may be fixed by sandwiching it between the heating element 22 and the volume reduction member 58 through swaging of the heating element 22. A portion of the heating element wiring 94 passes sequentially through the side hole 58b of the volume reduction member 58, the shaft hole 58a, and the space 70 between each outer shaft 54, 58, before being inserted into the first lumen 60 of the outer shaft 54. A portion of the heating element wiring 94 is located inside the volume reduction member 58 and is not located outside the volume reduction member 58 in a certain axial range of the volume reduction member 58. As a result, the heating element wiring 94 does not come into contact with the balloon 20 in a certain axial range of the volume reduction member 58 within the fluid chamber 50, and the risk of the heating element wiring 94 getting caught on the balloon 20 can be reduced.

[0067] Next, we will describe the transformation forms of each component described so far.

[0068] The catheter shaft 18 does not necessarily have to include an inner shaft 56. Alternatively, the catheter shaft 18 may have an outer shaft 54 ​​and an inner shaft 56, but may not have to include a volume-reducing member 58.

[0069] The number and arrangement of each lumen of the outer shaft 54 ​​are not particularly limited. For example, a first lumen 60 may be formed on the center line C54 of the outer shaft 54, and multiple lumens, including a second lumen 62, may be formed surrounding the first lumen 60. In addition, the outer shaft 54 ​​may have only one lumen. One of the supply lumen 64 and the discharge lumen 66 of the outer shaft 54 ​​may be opened at the distal end face 54a of the outer shaft 54, while the other of them may be opened at a location other than the distal end face 54a of the outer shaft 54. Furthermore, each lumen 64, 66 may be opened at a location other than the distal end face 54a of the outer shaft 54.

[0070] The balloon 20 may have a multilayer structure comprising an inner layer member and an outer layer member. In this case, the inner layer member may constitute the main body portion 20e, and the outer layer member may constitute the insertion passage forming portion 20f. In other words, the main body portion 20e and the insertion passage forming portion 20f may be separate parts. Alternatively, the balloon 20 may consist only of the main body portion 20e and not have the insertion passage forming portion 20f. In this case, the main body portion 20e of the balloon 20 may be composed of a single layer structure. The insertion passage 52 of the balloon 20 may be directly connected to the insertion lumen 90 of the catheter shaft 18. This assumes, for example, the absence of the covering tube 86. In this case, the reinforcing member 78 may be directly drawn from the insertion passage 52 of the balloon 20 to the insertion lumen 90 of the catheter shaft 18.

[0071] The heating element 22 may be fixed to a location other than the volume-reducing member 58 of the catheter shaft 18, such as the inner shaft 56. The distal end of the heating element wiring 94 may be located outside the volume-reducing member 58 within the fluid chamber 50.

[0072] The linear member 74 may be fixed to at least one of the catheter shaft 18 and the balloon 20 by adhesive or other means. The balloon catheter 10 does not need to be equipped with a reinforcing member 78.

[0073] The contents of each component described in the embodiments above are illustrative. The abstract technical ideas derived from these should not be interpreted restrictively to the contents of this specification. Many design changes, such as modifications, additions, and deletions, are possible for each component described in the embodiments. Such modifications are emphasized with the notation "this form" or "embodiment." However, design changes are also permitted for contents without such notation. Any combination of the above components is also valid. The hatching applied to the cross-sections in the drawings does not limit the material to which the hatching is applied. The structures and numerical values ​​mentioned in the embodiments and variations naturally include those that can be considered identical when considering manufacturing tolerances, etc. Components composed of a single member in the description herein may be composed of multiple members. Similarly, components composed of multiple members may be composed of a single member.

[0074] This disclosure relates to balloon catheters.

[0075] 10...Balloon catheter, 18...Catheter shaft, 20...Balloon, 20e...Main body, 20f...Insertion passage forming part, 22...Heating member, 50...Fluid chamber, 52...Insertion passage, 54...Outer shaft, 54a...Distal end face, 56...Inner shaft, 58...Volume reduction member, 64...Supply lumen, 66...Discharge lumen, 70...Section between shafts, 72...Gap, 74...Linear member, 78...Reinforcement member, 84...Internal space in tube, 86...Coating tube.

Claims

1. A balloon catheter comprising: a catheter shaft; a balloon provided on the distal portion of the catheter shaft, having an expandable portion that can be expanded by a fluid supplied inside; and a heating member capable of heating the fluid inside the balloon, wherein a fluid chamber is formed inside the balloon outside the catheter shaft, and a fluid that expands the balloon is supplied inside the balloon, and the catheter shaft comprises: an outer shaft; an inner shaft inserted into the outer shaft and penetrating at least the expandable portion of the balloon; and a volume-reducing member surrounding the inner shaft and reducing the volume of the fluid chamber.

2. The balloon catheter according to claim 1, wherein the volume-reducing member is provided in an axial range of more than half of the axial range in which the expansion portion is located.

3. The balloon catheter according to claim 1 or 2, wherein the balloon comprises a pair of cone portions provided at both axial ends of the expansion portion and a cylindrical portion provided between the pair of cone portions.

4. The balloon catheter according to claim 3, wherein the volume-reducing member is provided over the entire axial range of the cylindrical portion.

5. When a predetermined maximum expansion pressure is applied inside the balloon, the volume reduction rate is defined as the ratio, as a percentage of the volume of the cylindrical portion, to the volume of the cylindrical portion obtained by subtracting the volume of the fluid chamber in a certain axial range of the cylindrical portion from the volume of the cylindrical portion, and the volume reduction rate is 10% or more, according to claim 3 or 4.

6. The balloon catheter according to any one of claims 1 to 5, wherein the volume-reducing member is disposed distal to the outer shaft and comprises a linear member provided in an axial range spanning the intervening portion between the outer shaft and the volume-reducing member, and a reinforcing member provided in an axial range spanning the intervening portion.

7. The balloon catheter according to claim 6, comprising a main body portion that forms the fluid chamber and an insertion passage forming portion that forms an insertion passage between the main body portion and the balloon through which the linear member is inserted, wherein the linear member is permitted to move relative to the balloon and the catheter shaft in the longitudinal direction.

8. The balloon catheter according to claim 7, comprising a covering tube that covers the catheter shaft and forms an internal space between itself and the catheter shaft, wherein the reinforcing member is drawn out from the insertion passage into the internal space of the tube.

9. The balloon catheter according to any one of claims 1 to 8, wherein the outer shaft is formed with a supply lumen for supplying fluid to the fluid chamber and a discharge lumen through which fluid discharged from the fluid chamber flows, at least one of the supply lumen and the discharge lumen opens to the distal end face of the outer shaft, the volume reduction member is positioned distal to the outer shaft, and a gap is formed between the outer shaft and the volume reduction member.

10. The balloon catheter according to any one of claims 1 to 9, wherein the heating member is fixed to the volume reduction member.

11. The balloon catheter according to claim 10, wherein the volume-reducing member is a shaft member on which the inner shaft is arranged internally, and the heating member is embedded in the outer circumference of the volume-reducing member.

12. The balloon catheter according to claim 10 or 11, comprising wiring electrically connected to the heating member, wherein a portion of the wiring is arranged inside the volume-reducing member.

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