WO2024202775A1 - Balloon catheter - Google Patents

Abstract

[Problem] To provide a balloon catheter having desired pushability and pressure resistance, as well as improved catheterization. [Solution] A balloon catheter 10 has a distal end shaft 110 provided with an inner shaft 120. In at least a part of a portion of the inner shaft 120, the portion axially overlapping with a balloon 300, the cross-sectional space occupancy ratio of the cross-sectional area of a tube wall part of the inner shaft with respect to the total cross-sectional area, which includes an outer peripheral part of the inner shaft, is 30-40% at a cross-section orthogonal to the axis of a shaft part 100. The distal end shaft has a three-point bending load per unit strain of 0.10-0.25 N/mm in a predetermined range closer to the distal end side than a guide wire port 123a.

Description

Balloon catheter

The present invention relates to a balloon catheter.

Balloon catheters are known as medical devices used in procedures to expand lesions (such as narrowed areas) formed in biological lumens such as blood vessels, and for placing stents or other devices in lesions.

The balloon catheter may be configured to have an inner shaft with a guidewire lumen through which a guidewire can be inserted, an outer shaft arranged to define a fluid lumen through which fluid can flow between the inner shaft and the outer shaft, and a balloon connected to the tip of the inner shaft and the tip of the outer shaft (see Patent Document 1).

In addition, in the balloon catheter of Patent Document 1, the tip of the balloon is connected to the tip of the inner shaft, and the base end of the balloon is connected to the tip of the outer shaft. The balloon is arranged so as to overlap the inner shaft in the axial direction within a predetermined range on the tip side of the inner shaft, and defines an internal space between the balloon and the inner shaft into which a fluid can be injected. The inner shaft and the outer shaft together form the tip shaft, which is the tip side portion of the shaft section.

JP 2001-95924 A

In procedures using a balloon catheter, the balloon is delivered in a deflated state to the target site, such as a stenosis. Therefore, in order to improve the passage of the balloon through a stenosis, it is possible to reduce the outer diameter of the inner shaft, which is arranged to define an internal space between the balloon and the inner shaft. In addition, if the outer diameter of the inner shaft is formed small, the passage of the balloon catheter can be improved even when the balloon is expanded once and then deflated again to return to a rewrapped state.

In order to reduce the outer diameter of the inner shaft, for example, there are two possible methods: reducing the outer and inner diameters while maintaining the thickness of the tube wall of the inner shaft, or reducing the outer diameter by reducing the thickness of the tube wall while maintaining the inner diameter of the inner shaft.

Balloon catheters require the inner shaft to have a certain inner diameter due to the product specifications of the guidewire through which the inner shaft is inserted. For this reason, it is difficult to actively adopt the former method.

On the other hand, when the latter method is adopted, if the thickness of the inner shaft's tube wall is made too thin, the inner shaft may be crushed by the injection pressure of the fluid injected when expanding the balloon, and the lumen of the inner shaft may not be able to maintain the specified shape. Also, if the flexibility of the tip shaft increases excessively as a result of the inner shaft being made too thin, it becomes difficult to provide the shaft portion with sufficient pushability.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a balloon catheter that has the desired pushability and pressure resistance, as well as improved passability.

The present invention can be achieved by any of the following means (1) to (6).

(1) A balloon catheter comprising a shaft section and a balloon disposed at the distal end of the shaft section, the shaft section comprising an inner shaft having a guidewire lumen through which a guidewire can be inserted and a guidewire port disposed at the proximal end of the guidewire lumen, and an outer shaft disposed to define a fluid lumen through which a fluid for expanding the balloon can flow between the inner shaft and the inner shaft, the inner shaft has a cross-sectional space occupancy rate of 30% to 40% of the total cross-sectional area including the outer periphery of the inner shaft in at least a portion of a portion that overlaps with the balloon in the axial direction in a cross section perpendicular to the axis of the shaft section, and the distal shaft has a three-point bending load per unit deflection of 0.10 N/mm to 0.25 N/mm in a predetermined range distal to the guidewire port.

(2) The balloon catheter according to (1) above, wherein the inner shaft has a distal region arranged at a position overlapping with the balloon in the axial direction, and a proximal region arranged proximally of the distal region and having a larger outer diameter than the distal region, the distal end and proximal end of the balloon are arranged at positions overlapping with the distal region of the inner shaft in the axial direction, and the distal shaft has a three-point bending load per unit deflection of 0.10 N/mm or more and 0.25 N/mm or less in at least the range proximally of the position where the distal region overlaps with the proximal end of the balloon in the axial direction and in the proximal region.

(3) A balloon catheter as described in (2) above, which has a core wire reinforcing the shaft portion, at least a portion of the core wire is arranged to overlap the base end region in the axial direction, and the distal shaft has a three-point bending load per unit deflection of 0.10 N/mm or more and 0.25 N/mm or less from the position where the distal shaft overlaps the base end of the balloon in the axial direction in the tip region to the position of the tip of the core wire.

(4) A balloon catheter as described in (2) or (3) above, in which the axial length of the tip region of the inner shaft is longer than the axial length of the base region.

(5) A balloon catheter as described in (2) or (3) above, in which the axial length of the base end region of the inner shaft is longer than the axial length of the tip end region.

(6) A balloon catheter according to any one of (2) to (5) above, in which the cross-sectional area of the tube wall portion of the base end region of the inner shaft occupies 22% to 34% of the cross-sectional area of the lumen of the outer shaft in a cross-sectional cross section perpendicular to the axis of the shaft portion.

The present invention provides a balloon catheter that has the desired pushability and pressure resistance, as well as improved passability.

FIG. 1 is a diagram showing a balloon catheter according to an embodiment. FIG. 2 is an enlarged cross-sectional view of the vicinity of the tip of the balloon catheter according to the embodiment. FIG. 2 is a partial cross-sectional view of a shaft portion of a balloon catheter according to an embodiment. FIG. 1 is a plan view of a balloon catheter according to an embodiment. 5A is an orthogonal cross-sectional view of the inner shaft taken along the line 5A-5A shown in FIG. 4. 6A is a cross-sectional view of the distal shaft taken along the line 6A-6A shown in FIG. 4, which is perpendicular to the axis of the distal shaft. FIG. 1 is a diagram for explaining an embodiment of the present invention.

Below, an embodiment of the present invention will be described with reference to the drawings. Note that the dimensional ratios in the drawings have been exaggerated for the convenience of explanation and may differ from the actual ratios.

In the balloon catheter 10 of this embodiment described below, the "tip side" is the side that is introduced into the living body, and is indicated by the arrow X1 in the figure. The "base side" is the opposite side to the tip side, and is indicated by the mark X2 in the figure. In this specification, the direction indicated by the arrows X1-X2 is referred to as the "axial direction," and the cross section perpendicular to the axial direction (the cross sections shown in Figures 5 and 6) is referred to as the cross section perpendicular to the axial direction.

(Balloon catheter 10)
As shown in Figures 1 and 3, the balloon catheter 10 comprises a shaft portion 100, a balloon 300 disposed at the tip of the shaft portion 100, and a reinforcing core wire 200 connected to the shaft portion 100 at a position closer to the base end than the balloon 300.

The balloon catheter 10 is configured as a medical device that treats a narrowed area by inserting the shaft portion 100 into a biological lumen and expanding the balloon 300 located at the tip of the shaft portion 100 at the narrowed area (lesion site) to expand the narrowed area.

The balloon catheter 10 can be configured as a PTCA dilation balloon catheter used, for example, to widen narrowed areas of a coronary artery. However, the balloon catheter 10 can also be configured to be used for the purpose of treating and improving narrowed areas formed in biological organs, such as other blood vessels, bile ducts, tracheas, esophagus, other digestive tracts, urethras, ear and nose cavities, and other organs.

The balloon catheter 10 is configured as a so-called rapid exchange type catheter, in which a guidewire port 123a through which a guidewire GW can enter and exit is formed near the tip of the shaft portion 100.

(Shaft portion 100)
As shown in FIGS. 1, 2 and 3 , the shaft portion 100 can be configured to include three shafts: a distal shaft 110 , an intermediate shaft 140 , and a proximal shaft 150 .

(Tip shaft 110)
The distal shaft 110 may be configured to include an inner shaft 120 and an outer shaft 130 as shown in FIGS.

As shown in FIG. 3, the inner shaft 120 includes a guidewire lumen 125 through which a guidewire GW can be inserted, and a guidewire port 123a disposed at the base end of the guidewire lumen 125. The guidewire port 123a can be configured as a base end opening located at the base end 123 of the inner shaft 120.

As shown in FIG. 2, the tip 301 of the balloon 300 is connected to the tip 121 of the inner shaft 120.

A flexible tip tip 20 can be placed at the tip 121 of the inner shaft 120. The tip tip 20 can be made of, for example, a flexible resin member that has heat shrinkability.

As shown in FIG. 2, the inner shaft 120 can be configured to have a contrast marker portion 30 for indicating a predetermined position of the balloon 300 (e.g., the center position of the straight portion 305 of the balloon 300). The contrast marker portion 30 can be made of, for example, a metal such as platinum, gold, silver, iridium, titanium, or tungsten, or an alloy of these metals.

The inner shaft 120 is positioned so as to pass through the internal space 305a of the balloon 300. The guidewire lumen 125 of the inner shaft 120 extends to the distal side beyond the internal space 305a of the balloon 300. The distal end 121 of the inner shaft 120 is provided with a distal opening 121a through which the guidewire GW can be introduced.

As shown in Figures 2 and 3, the inner shaft 120 has a distal end region 126 that is positioned so as to overlap with the balloon 300 in the axial direction, and a proximal end region 127 that is positioned proximal to the distal end region 126 and has a larger outer diameter than the distal end region 126.

The balloon catheter 10 has a relatively small diameter tip region 126 formed on the inner shaft 120, which allows for small profiling when the balloon 300 is deflated. In addition, the balloon catheter 10 has a relatively large diameter base region 127 formed on the inner shaft 120, which allows for increased rigidity of the tip shaft 110 in the range where the base region 127 of the inner shaft 120 is formed.

As shown in FIG. 4, the inner shaft 120 can be configured so that the axial length of the distal region 126 is longer than the axial length of the proximal region 127 (the ratio of the length to the overall length of the inner shaft 120 is greater). By configuring it in this way, a region that has a large cross-sectional area through which fluid can flow can be formed long along the axial direction within the fluid lumen 135 formed around the distal region 126, making it possible to shorten the deflation time.

In addition, the inner shaft 120 can also be configured so that the axial length of the base end region 127 is longer than the axial length of the tip region 126, which is the opposite to the above. When configured in this way, the axial length of the relatively thin tip region 126 is shortened, and the region along the axial direction of the base end region 127, where the bending load is large, becomes longer, thereby improving the pushability of the tip shaft 110.

As shown in FIG. 3, the distal region 126 can be provided, for example, from the distal end 121 of the inner shaft 120 to a position shifted toward the proximal end by a predetermined length from the position where it axially overlaps with the proximal end 303 of the balloon 300. Also, as shown in FIG. 3, the proximal region 127 can be provided in the range from the proximal end of the distal region 126 to the proximal end 123 where the guidewire port 123a is located.

As shown in FIG. 3, the outer shaft 130 is positioned to define a fluid lumen 135 between the outer shaft 130 and the inner shaft 120 through which fluid can flow to inflate the balloon 300.

The inner shaft 120 is positioned so as to pass through the inside of the outer shaft 130. The fluid lumen 135 is formed as a space partitioned between the outer peripheral surface of the inner shaft 120 and the inner peripheral surface of the outer shaft 130.

As shown in FIG. 2, the tip 131 of the outer shaft 130 is disposed closer to the base end than the tip 121 of the inner shaft 120. The base end 303 of the balloon 300 is connected to the tip 131 of the outer shaft 130.

The tip 131 of the outer shaft 130 is provided with a tip opening 131a that communicates with the internal space 305a of the balloon 300. Fluid supplied via the fluid lumen 135 can be injected into the internal space 305a of the balloon 300 via the tip opening 131a. When discharging fluid from the internal space 305a of the balloon 300, it can be moved to the base end side of the shaft portion 100 via the tip opening 131a and the fluid lumen 135.

The inner shaft 120 and the outer shaft 130 can be made of, for example, polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer; thermoplastic resins such as soft polyvinyl chloride; various elastomers such as polyurethane elastomers, polyamide elastomers, and polyester elastomers; and crystalline plastics such as polyamide, crystalline polyethylene, and crystalline polypropylene.

In the balloon catheter 10 according to this embodiment, the following configurations can be adopted for each part of the distal shaft 110.

The inner shaft 120 can be configured so that, in at least a portion of the portion that overlaps with the balloon 300 in the axial direction (the portion where the internal space 305a is partitioned), in an axial cross-section of the shaft portion 100, the cross-sectional space occupancy rate of the cross-sectional area of the tubular wall portion of the inner shaft 120 to the total cross-sectional area including the outer periphery of the inner shaft 120 (total cross-sectional area of the inner shaft 120 [ ^mm2 ] / cross-sectional area of the tubular wall portion of the inner shaft 120 [ ^mm2 ] x 100 [%]) is 30% or more and 40% or less.

The above "total cross-sectional area" refers to the area of the entire range located inside the outer circumferential surface of the inner shaft 120 on the axial cross-sectional view shown in FIG. 5. In addition, the above "cross-sectional area of the tube wall portion" refers to the area of the region corresponding to the tube wall portion of the inner shaft 120 on the axial cross-sectional view shown in FIG. 5.

The distal shaft 110 can be configured so that the three-point bending load per unit deflection is 0.10 N/mm or more and 0.25 N/mm or less in a specified range distal to the guidewire port 123a. The "bending load per unit deflection" refers to the load value determined by a three-point bending load test described in the examples below.

The balloon catheter 10 has a cross-sectional space occupancy rate of 30% or more and 40% or less as described above, which allows the inner shaft 120 to be made thinner while having an appropriate tube wall thickness that prevents the inner shaft 120 from collapsing when fluid is injected into the internal space 305a of the balloon 300. In addition, the balloon catheter 10 has a three-point bending load per unit deflection at a specified position of the tip shaft 110 of 0.10 N/mm or more and 0.25 N/mm or less, which allows the tip shaft 110 to have the desired pushability while maintaining its ability to follow blood vessels, etc.

When the inner shaft 120 is formed with a distal region 126 and a proximal region 127 as in the balloon catheter 10 of this embodiment, the distal shaft 110 can be configured so that the three-point bending load per unit deflection is 0.10 N/mm or more and 0.25 N/mm or less in at least the range of the distal region 126 on the proximal side of the position where it axially overlaps with the proximal end 303 of the balloon 300 and in the proximal region 127.

Furthermore, when the balloon catheter 10 according to this embodiment includes a core wire 200 that reinforces the shaft portion 100, the distal shaft 110 can be configured so that the three-point bending load per unit deflection is 0.10 N/mm or more and 0.25 N/mm or less from the position where it axially overlaps with the base end portion 303 of the balloon 300 to the position of the tip of the core wire 200 in at least the distal region 126.

In the balloon catheter 10, in the axial cross section of the shaft portion 100 shown in Figure 6, the cross-sectional space occupancy rate of the cross-sectional area of the tube wall portion of the base end region 127 of the inner shaft 120 relative to the cross-sectional area of the inner cavity of the outer shaft 130 (which in this embodiment corresponds to the fluid lumen 135 located distal to the guidewire port 123a) can be set to 22% or more and 34% or less. By configuring it in this way, it is possible to improve the pushability of the distal shaft 110 in the base end region 127 while achieving smooth flow of fluid in the fluid lumen 135.

(Intermediate shaft 140)
3 and 4 , the intermediate shaft 140 is disposed on the proximal end side of the distal shaft 110 (the inner shaft 120 and the outer shaft 130). The intermediate shaft 140 is connected to the inner shaft 120 and the outer shaft 130.

As shown in FIG. 3, the base end 123 of the inner shaft 120 is connected to the base end 133 of the outer shaft 130 with the base end 123 inserted into the outer shaft 130 near the guidewire port 123a. The tip end 141 of the intermediate shaft 140 is connected to the inner shaft 120 and the outer shaft 130 with a circumferential portion (a portion on the upper side of the axial cross section) inserted into the outer shaft 130. In this way, the three shafts, the inner shaft 120, the outer shaft 130, and the intermediate shaft 140, are connected near the guidewire port 123a.

The method for connecting the inner shaft 120, the outer shaft 130, and the intermediate shaft 140 is not particularly limited, but for example, thermal fusion can be used.

The intermediate shaft 140 has a fluid lumen 145 extending in the axial direction. The fluid lumen 145 of the intermediate shaft 140 is arranged to communicate with the fluid lumen 135 of the tip shaft 110 near the guidewire port 123a.

The intermediate shaft 140 may be made of the same materials as those exemplified as the materials for the inner shaft 120 and the outer shaft 130.

(Proximal Shaft 150)
1 , 3 and 4 , the proximal shaft 150 is disposed on the proximal side of the intermediate shaft 140. A tip end 151 of the proximal shaft 150 is connected to the proximal end 143 of the intermediate shaft 140.

The inside of the base shaft 150 is provided with a fluid lumen 155 through which fluid can flow. The fluid lumen 155 of the base shaft 150 is arranged to communicate with the fluid lumen 145 of the intermediate shaft 140.

As shown in FIG. 3, the core wire 200 can be fixed to a predetermined position of the base end shaft 150 (e.g., near the tip 151) via a predetermined fixing part 230. Any method can be used to fix the core wire 200 to the base end shaft 150 depending on the materials of the base end shaft 150 and the core wire 200, but welding, for example, can be used.

As shown in FIG. 1, a hub 40 is disposed on the base end side of the base shaft 150, to which a supply device (e.g., an indeflator) can be connected to control the movement of fluid in and out of the fluid lumen 155. A kink-resistant protector 50, which is known in the field of catheters, can be attached to the tip side of the hub 40.

When the balloon 300 is expanded, fluid can be injected into the internal space 305a of the balloon 300 via the hub 40, the fluid lumen 155 of the base shaft 150, the fluid lumen 145 of the intermediate shaft 140, and the fluid lumen 135 of the distal shaft 110. When the balloon 300 is deflated, fluid can be discharged to the outside of the balloon catheter 10 via the fluid lumen 135 of the distal shaft 110, the fluid lumen 145 of the intermediate shaft 140, the fluid lumen 155 of the base shaft 150, and the hub 40.

As a constituent material of the proximal shaft 150, for example, a metal material having a relatively high rigidity can be selected. Examples of such metal materials include stainless steel, stainless steel ductile alloy, Ni-Ti alloy, brass, and aluminum. In addition, as a material for the proximal shaft 150, it is also possible to use a resin material having a relatively high rigidity, such as polyimide, polyvinyl chloride, and polycarbonate, if necessary.

(Balloon 300)
As shown in Fig. 2, the balloon 300 is connected to the inner shaft 120 and the outer shaft 130. The balloon 300 has a distal end 301 connected to the inner shaft 120, a proximal end 303 connected to the outer shaft 130, and a straight portion 305 extending in a substantially straight line between the distal end 301 and the proximal end 303. Note that Fig. 2 shows the cross-sectional shape of the balloon 300 in an expanded state.

As shown in FIG. 2, the distal end 301 of the balloon 300 and the proximal end 303 of the balloon 300 are positioned so as to overlap with the distal end region 126 of the inner shaft 120 in the axial direction.

The balloon 300 expands in the radial direction of the inner shaft 120 by injecting a fluid into the internal space 305a defined between the balloon 300 and the inner shaft 120. The fluid used to expand the balloon 300 can be, for example, a mixture of a contrast agent and saline.

The balloon 300 can be made of a material such as polyethylene, polypropylene, polyolefins such as ethylene-propylene copolymers, polyesters such as polyethylene terephthalate, thermoplastic resins such as polyvinyl chloride, ethylene-vinyl acetate copolymers, cross-linked ethylene-vinyl acetate copolymers, polyurethane, polyamides, polyamide elastomers, polystyrene elastomers, silicone rubber, latex rubber, etc.

(Core Wire 200)
The core wire 200 can be formed, for example, from a rod-shaped member having a circular cross section perpendicular to the axis.

As shown in FIG. 3, the core wire 200 can be positioned within the fluid lumen 135 of the distal shaft 110 and the fluid lumen 135 of the intermediate shaft 140. The distal end 201 of the core wire 200 can be positioned to axially overlap the proximal region 127 of the inner shaft 120.

The core wire 200 is preferably made of a metal material with good rigidity and workability, such as stainless steel, stainless steel ductile alloy, Ni-Ti alloy, etc.

(Example)
The following describes the operation and effect of the balloon catheter 10 through examples. The scope of the present invention is not limited to the contents of the examples described below.

Figure 7 shows the specifications and performance evaluation results of the balloon catheter 10 used in Examples 1 and 2, and the specifications and performance evaluation results of the balloon catheters used in Comparative Examples 1 and 2.

The basic configuration of the balloon catheters used in Examples 1 and 2 and Comparative Examples 1 and 2 (configuration other than the dimensions shown in FIG. 7) is the same as that of the previously described embodiment.

The balloon catheters of Examples 1 and 2 and Comparative Examples 1 and 2 have the following in common.
The three-point bending load per unit deflection of the distal shaft 110 is 0.10 N/mm or more and 0.25 N/mm or less from the position where the distal shaft 110 axially overlaps with the base end 303 of the balloon 300 in the distal region 126 to the position of the distal end of the core wire 200. This value was measured in a three-point bending test in which the distal shaft 110 was placed on a support stand with a fulcrum distance of 16 mm, and a measuring pusher was pushed 1 mm toward the center position between the support stands at 50 mm/sec.
The "total cross-sectional area" shown in the table is the total cross-sectional area including the outer periphery of the inner shaft 120. The "tube wall cross-sectional area" is the cross-sectional area of the tube wall portion of the inner shaft 120. The "cross-sectional space occupancy rate" is a value calculated by (total cross-sectional area of the inner shaft 120 [ ^mm2 ]/cross-sectional area of the tube wall portion of the inner shaft 120 [ ^mm2 ] × 100 [%]).

The performance evaluation was based on (1) a pressure resistance test of the inner shaft 120 and (2) the outer diameter of the inner shaft 120.

(1) The pressure resistance test of the inner shaft 120 was carried out under the following conditions.
Using an indeflator known in the medical field, the internal space 305a of the balloon 300 was filled with a fluid, and when a pressure of 30 atm was applied, it was confirmed whether or not the portion of the inner shaft 120 where the balloon 300 was placed (the tip region 126) was crushed (whether or not the guidewire lumen 125 was deformed into a non-circular cross-sectional shape). Physiological saline was used as the fluid.

(2) Size of the outer diameter of the inner shaft 120: In a procedure using a typical balloon catheter 10 (a procedure for expanding a narrowed portion of a blood vessel, etc.), we considered whether the outer diameter was large enough to ensure the desired passability when the balloon 300 was deflated.

(Evaluation Results)
As a result of comparing Examples 1 and 2 with Comparative Examples 1 and 2, the following effects can be recognized in Examples 1 and 2.

The cross-sectional space occupancy rates of Examples 1 and 2 are 32% and 40%, respectively (30% to 40%), both of which are larger than the 27% of Comparative Example 1. In addition, Comparative Example 2, which has a cross-sectional space occupancy rate of 51%, can be confirmed to have the desired pressure resistance, similar to Examples 1 and 2. From these results, it is considered that the distal shaft 110 can be configured to have the desired pressure resistance that can prevent the inner shaft 120 from being crushed, as long as the cross-sectional space occupancy rate is 30% to 40%. On the other hand, Comparative Example 2 has no problems in terms of pressure resistance, but the outer diameter of the inner shaft 120 is adjusted to increase the cross-sectional space occupancy rate by increasing the outer diameter, so that the outer diameter is excessively large. Therefore, it is not possible to sufficiently reduce the profile when the balloon is deflated, and it is considered that it is difficult to improve passability.

The above evaluation tests confirmed that, as in the balloon catheters 10 of Examples 1 and 2, if the three-point bending load per unit deflection at a predetermined position of the distal shaft 110 is 0.10 N/mm or more and 0.25 N/mm or less, and the cross-sectional space occupancy rate at a predetermined position of the inner shaft 120 is 30% or more and 40% or less, the desired pushability and pressure resistance are obtained, and passability is improved.

This application is based on Japanese Patent Application No. 2023-051448, filed on March 28, 2023, the disclosure of which is incorporated by reference in its entirety.

10 Balloon catheter 100 Shaft portion 110 Distal shaft 120 Inner shaft 123a Guidewire port 125 Guidewire lumen 126 Distal region 127 Base region 130 Outer shaft 135 Fluid lumen 140 Intermediate shaft 145 Fluid lumen 150 Base shaft 155 Fluid lumen 200 Core wire 300 Balloon 301 Distal portion of balloon 303 Base end portion of balloon 305a Internal space GW of balloon Guidewire

Claims (6)

A balloon catheter comprising a shaft portion and a balloon disposed at a distal end of the shaft portion,
The shaft portion is
a distal end shaft configured to include an inner shaft having a guidewire lumen through which a guidewire can be inserted and a guidewire port disposed at a base end of the guidewire lumen, and an outer shaft disposed to define a fluid lumen through which a fluid for expanding the balloon can flow between the inner shaft and the outer shaft;
in at least a part of a portion of the inner shaft that overlaps with the balloon in the axial direction, in a cross-sectional section orthogonal to an axis of the shaft portion, a cross-sectional space occupancy ratio of a cross-sectional area of a tube wall portion of the inner shaft to a total cross-sectional area including an outer circumferential portion of the inner shaft is 30% or more and 40% or less,
A balloon catheter, wherein the distal shaft has a three-point bending load per unit deflection of 0.10 N/mm or more and 0.25 N/mm or less in a predetermined range distal to the guidewire port. The inner shaft has a distal end region arranged at a position overlapping with the balloon in the axial direction, and a proximal end region arranged on a proximal side of the distal end region and having an outer diameter larger than that of the distal end region,
a distal end of the balloon and a proximal end of the balloon are disposed axially overlapping the distal end region of the inner shaft;
2. The balloon catheter according to claim 1, wherein the distal shaft has a three-point bending load per unit deflection of 0.10 N/mm or more and 0.25 N/mm or less in at least a range on the proximal side of a position where the distal shaft axially overlaps with the proximal end of the balloon in the distal region and in the proximal region. A core wire is provided to reinforce the shaft portion.
At least a portion of the core wire is arranged to overlap the base end region in the axial direction,
3. The balloon catheter according to claim 2, wherein the distal shaft has a three-point bending load per unit deflection of 0.10 N/mm or more and 0.25 N/mm or less from a position where the distal shaft axially overlaps with the base end of the balloon to a position of the tip of the core wire in the distal region. The balloon catheter according to claim 2 or 3, wherein the axial length of the distal end region of the inner shaft is longer than the axial length of the proximal end region. The balloon catheter according to claim 2 or 3, wherein the axial length of the base end region of the inner shaft is longer than the axial length of the tip end region. The balloon catheter according to claim 2, wherein the cross-sectional area of the wall portion of the base end region of the inner shaft occupies a cross-sectional space ratio of 22% to 34% of the cross-sectional area of the lumen of the outer shaft in a cross-sectional cross section perpendicular to the axis of the shaft portion.