Balloon catheter

Abstract

To provide a balloon catheter effectively eliminating a rigidity gap between components.SOLUTION: A balloon catheter 10 according to the present invention comprises a metal proximal tube 1, a coil member 2 attached to a tip side of the proximal tube 1 and formed by spirally winding at least one metal wire, a resin outer tube 3 connected to the tip side of the proximal tube 1 so as to cover the coil member 2, and a balloon 5 connected to the tip side of the outer tube 3. The coil member 2 includes a plurality of joint portions 22 formed by joining adjacent metal wires 21 continuously in the circumferential direction. An interval of two adjacent joint portions 22 is gradually enlarged toward the tip side, so that rigidity of the tip side of the coil member 2 is lower than that of the base side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A balloon catheter, which is used to dilate stenotic areas in a body cavity, such as a blood vessel, is known as a type of catheter used to treat a region within a body cavity. A balloon catheter mainly comprises a balloon as an expandable body, an outer tube to which the balloon is attached at its distal end, and an inner tube disposed within the lumen of the outer tube and having a distal opening at the distal end of the balloon and a rear opening on the outer lateral surface of the outer tube. The outer tube is used to circulate a dilating liquid, such as a contrast agent or saline solution, for expanding the balloon through a lumen provided between the outer tube and the inner tube, and a guide wire is inserted through the inner tube to guide the balloon catheter to the lesion.

[0003] Such balloon catheters are inserted into blood vessels or the like and positioned at the desired location, with a force applied by a physician or other operator to push the catheter from the proximal side toward the distal end. Balloon catheters are required to have high transmission of the force pushing the catheter in the axial direction, or what is known as a pushing force (excellent pushability), as well as excellent operability in the distal portion. Therefore, a structure is generally adopted in which a hollow metal tubular member called a hypotube is connected to the proximal connector tip, and a resin outer tube is connected to the tip of the hypotube, thereby increasing the rigidity of the proximal side.

[0004] However, in balloon catheters equipped with such a hypotube at the proximal end, there is a difference in rigidity between the hypotube and the outer tube, which can lead to breakage around the connection between the hypotube and the outer tube when the balloon catheter is pushed in, reducing pushability. To solve this problem, Patent Documents 1 and 2, for example, disclose balloon catheters that improve pushability by inserting a core wire from the inside of the hypotube into the inside of the outer tube. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-022166 [Patent Document 2] Japanese Patent Application Publication No. 2014-036732 Summary of the Invention [Problem to be solved by the invention]

[0006] However, as in the balloon catheters disclosed in Patent Documents 1 and 2, simply inserting a core wire from the inside of the hypotube to the inside of the outer tube does not sufficiently eliminate the rigidity gap, and a structure is needed that more effectively improves the gap between the rigidity of the hypotube and the rigidity of the outer tube.

[0007] The present invention has been made in view of the above points, and has as its object to provide a balloon catheter that effectively eliminates the rigidity gap between the constituent members and has excellent pushability. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a balloon catheter comprising: a metal base-end tube; a coil member attached to the tip end of the base-end tube and formed by spirally winding at least one metal wire; a resin outer tube connected to the tip end of the base-end tube so as to cover the coil member; and a balloon connected to the tip end of the outer tube, wherein the rigidity of the tip end of the coil member is lower than that of the base end (Invention 1).

[0009] According to this invention (Invention 1), by attaching a coil member whose distal stiffness is lower than that of the proximal side to the distal side of the proximal tube and placing it inside the proximal side of the outer tube, the stiffness of the joint between the high-stiffness metal proximal tube and the low-stiffness resin outer tube decreases from the proximal side to the distal side, effectively eliminating the stiffness gap between the proximal tube and the outer tube, making it possible to provide a balloon catheter with excellent pushability.In addition, compared to conventional configurations in which a core wire is inserted inside the proximal tube, a wider flow path for the balloon inflation medium can be provided, shortening the inflation time.

[0010] The above invention (Invention 1) may comprise an inner tube disposed inside the outer tube and through which a guidewire is inserted, and a guidewire port formed at the portion where the base end of the inner tube is joined to the outer tube, and the coil member may be disposed on the outer tube on the base end side of the guidewire port (Invention 2), or may comprise an inner tube disposed inside the outer tube and through which a guidewire is inserted, and a guidewire port formed on the base end side of the base end tube, and the inner tube may extend from the guidewire port into the base end tube and the coil member (Invention 3).

[0011] In the above inventions (Inventions 1-3), the coil member may have a plurality of joints that join adjacent metal wires continuously in the circumferential direction, and the distance between two adjacent joints may gradually increase toward the tip (Invention 4).

[0012] According to this invention (Invention 4), in the coil member, at locations where joints are formed where adjacent metal wires are joined continuously in the circumferential direction, the movement of the metal wires is restricted and rigidity is increased, so by gradually increasing the spacing between the joints formed in the coil member toward the tip, the rigidity of the coil member can be gradually decreased from the base end side toward the tip end. By providing such a coil member, the rigidity gap between the base end tube and the outer tube can be more effectively eliminated.

[0013] In the above inventions (Inventions 1-4), the cross section of the metal wires constituting the coil member may be substantially rectangular (Invention 5). [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a balloon catheter that effectively eliminates the rigidity gap between the constituent members and has excellent pushability. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an explanatory diagram showing the overall structure of a balloon catheter according to an embodiment of the present invention. [Figure 2] 2 is an explanatory diagram showing an enlarged view of the structure of a portion (portion X in FIG. 1) of the balloon catheter. [Figure 3] FIG. 10 is an explanatory diagram showing a modified example of a hypotube with a metal coil attached thereto. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing the structure of a balloon catheter 10 according to this embodiment, and FIG. 2 is an explanatory diagram showing an enlarged view of the structure of a portion of the balloon catheter 10 (portion X in FIG. 1). Note that the present invention is not limited to the embodiment described below, and the embodiment is merely an example described to explain the technical features of the present invention. Furthermore, the shapes and dimensions shown in the drawings are shown solely to facilitate understanding of the contents of the present invention and do not accurately reflect the actual shapes and dimensions.

[0017] As used herein, the term "distal side" refers to the axial direction of the tubes constituting the balloon catheter, in which the balloon catheter advances toward the treatment site. The term "proximal side" refers to the axial direction of the tubes constituting the balloon catheter, in the opposite direction from the distal side. Furthermore, the term "distal" refers to the distal end of a given component or component, and the term "proximal end" refers to the proximal end of a given component or component. Furthermore, the term "distal portion" refers to the portion of a given component or component that includes the distal end and extends from the distal end toward the proximal end to the midpoint of the component, etc., and the term "proximal end" refers to the portion of a given component or component that includes the proximal end and extends from the proximal end toward the distal end to the midpoint of the component, etc. Note that in Figures 1 and 2, the left side of the figure represents the "distal side" that is inserted into the body, and the right side represents the "proximal side" that is operated by a surgeon, such as a physician.

[0018] The balloon catheter 10 is used to treat, for example, occlusions or narrowings in cardiac blood vessels, and as shown in Figure 1, it comprises a hypotube 1, a metal coil 2, an outer tube 3, an inner tube 4, a balloon 5, a distal tip 6, a connector 7, and a core wire 8.

[0019] The hypotube 1 is a tubular member made of metal. The distal end of the hypotube 1 is inserted into and fixed to the proximal end of the outer tube 3. The hypotube 11 has an inner lumen penetrating therethrough along the axial direction, which, together with the lumen of the outer tube 3 (and the metal coil 2) described below, constitutes an inflation lumen for supplying a fluid for inflating the balloon 5. A connector 7 is attached to the proximal end of the hypotube 1. The distal end of the hypotube 1 may be provided with a hole or a slit to reduce the rigidity of the distal end of the hypotube 1 and thereby reduce the rigidity gap between the hypotube 1 and the metal coil 2.

[0020] In this embodiment, the outer diameter of the hypotube 1 is set in the range of 0.60 to 0.90 mm, and the inner diameter is set in the range of 0.45 to 0.60 mm. The material of the hypotube 1 is not particularly limited, but examples thereof include stainless steel and superelastic alloys such as Ni-Ti alloys.

[0021] The metal coil 2 is a coil member formed by helically winding at least one metal wire 21 and is attached to the distal end of the hypotube 1 using known fastening means such as welding or adhesive. The metal coil 2 may be attached to the hypotube 1 by, for example, abutting the proximal end of the metal coil 2 against the distal end of the hypotube 1, inserting the distal end of the hypotube 1 into the lumen of the metal coil 2 from the proximal end, or conversely, inserting the proximal end of the metal coil 2 into the lumen of the hypotube 1 from the distal end. The metal coil 2 may be a single-filament coil formed by winding a single metal wire 21, or a multi-filament coil formed by winding multiple metal wires 21. The metal wire 21 constituting the metal coil 2 is preferably a flat wire having a substantially rectangular cross section to ensure the rigidity of the metal coil 2. However, it may also be a round wire having a substantially circular cross section or other irregularly shaped wire.

[0022] In this embodiment, the outer diameter of the metal coil 2 is set in the range of 0.55 to 0.90 mm, and the inner diameter is set in the range of 0.40 to 0.60 mm. For example, in the case of a rapid exchange type as shown in FIGS. 1 and 2, it may be approximately 0.55 to 0.66 mm, and in the case of an over-the-wire type, it may be approximately 0.80 to 0.90 mm. The axial length of the metal coil 2 is set in the range of 100 to 300 mm. For example, in the case of a rapid exchange type, it may be approximately 100 to 200 mm, and in the case of an over-the-wire type, it may be approximately 100 to 300 mm. The material of the metal wires 21 constituting the metal coil 2 is not particularly limited, but examples thereof include stainless steel and superelastic alloys such as Ni-Ti alloys. The metal wires 21 and the hypotube 1 may be made of the same metal or different metals. When the metal coil 2 is placed over the outside of the hypotube 1, the inner diameter of the metal coil 2 is set to be larger than the outer diameter of the hypotube 1, and when the metal coil 2 is placed inside the hypotube 1, the outer diameter of the metal coil 2 is set to be smaller than the inner diameter of the hypotube 1.

[0023] The outer tube 3 is a tubular resin member connected to the distal end of the hypotube 1 so as to cover the metal coil 2. The outer tube 3 has an inner cavity that penetrates along the axial direction, and this inner cavity forms an inflation lumen for supplying a fluid for inflating the balloon 5.

[0024] In this embodiment, the inner diameter of the outer tube 3 is set to be larger than the outer diameter of the metal coil 2. Examples of materials that form the outer tube 3 include resin materials such as polyamide, polyamide elastomer, polyolefin, polyester, and polyester elastomer. The outer tube 3 may be formed entirely from the same resin material, or may be formed partially using different resin materials.

[0025] The inner tube 4 is a tubular member made of resin and disposed inside the outer tube 3. The inner tube 4 has a lumen penetrating therethrough along the axial direction, which constitutes a guidewire lumen through which a guidewire (not shown) is inserted. The gap between the inner circumferential surface of the outer tube 3 and the outer circumferential surface of the inner tube 4 forms part of an inflation lumen for circulating a liquid for inflating the balloon 5. The base end of the inner tube 4 is joined (welded) to the side surface of the outer tube 3, and this joined portion forms a guidewire port 41 on the base end side. The distal end side of the inner tube 4 extends from the distal end of the outer tube 3 and is inserted into the balloon 5, with its distal end protruding from the distal end mounting portion 22 of the balloon 5 toward the distal side.

[0026] In this embodiment, the outer diameter of the inner tube 4 is set smaller than the inner diameter of the outer tube 3 to allow the flow of the liquid for inflating the balloon 5, and the inner diameter is set large enough to allow the insertion of a guide wire. Examples of materials that can be used to form the inner tube 4 include resin materials such as polyamide, polyamide elastomer, polyolefin, polyester, and polyester elastomer. The entire inner tube 4 may be made of the same resin material, or portions may be made of different resin materials.

[0027] The balloon 5 is connected to the distal end of the outer tube 3 and has an expansion section 21 at the center in the axial direction for expanding the balloon 5, a distal attachment section 22 attached to the outer peripheral surface of the distal end of the inner tube 4 on the distal end side, and a proximal attachment section 23 attached to the outer peripheral surface of the distal end of the outer tube 3 on the proximal end side. Examples of materials that can be used to form the balloon 5 include resin materials such as polyamide, polyamide elastomer, polyolefin, polyester, and polyester elastomer. The entire balloon 5 may be made of the same resin material, or portions may be made of different resin materials.

[0028] The distal tip 6 is a tubular (hollow) member connected to the distal end of the inner tube 4. The distal tip 6 has an inner cavity that penetrates along the axial direction, and can be formed so as to have a tapered shape with a diameter that gradually decreases toward the distal end. A distal guidewire port (not shown) is provided at the distal end of the distal tip 6, from which a guidewire inserted into the inner tube 4 extends. Examples of materials that can be used to form the distal tip 6 include resin materials such as polyurethane, polyurethane elastomer, polyamide, and polyamide elastomer.

[0029] The connector 7 is a member that allows the operator to grasp the balloon catheter 10, and is connected to the proximal end of the hypotube 1. The connector 7 has a lumen (not shown) that penetrates along the axial direction, and the distal opening of the lumen is in communication with the lumen of the hypotube 1. When a liquid such as a contrast agent or saline solution for inflating the balloon 5 is supplied from an indeflator (not shown) attached to the connector 7, the liquid passes through the lumen (inflation lumen) of the connector 7, hypotube 1, and outer tube 3, thereby inflating the balloon 5.

[0030] The core wire 8 is a rod-like member having an elongated shape as a whole, which is inserted through the hypotube 1, the metal coil 2, and the outer tube 3 and extends in the axial direction. The core wire 8 is a member for increasing the rigidity and strength of the proximal end side of the balloon catheter 10, and is made of, for example, stainless steel or a superelastic alloy such as a Ni-Ti alloy.

[0031] The method for linking, connecting, or attaching each of the components that make up the balloon catheter 10 (hypotube 1, metal coil 2, outer tube 3, inner tube 4, balloon 5, distal tip 6, and connector 7) is not particularly limited as long as it does not impair the effects of the present invention. For example, methods such as welding resin materials together by heating, welding metal materials together by laser irradiation or heating, and bonding using an adhesive can be used.

[0032] 2, the metal coil 2 is disposed on the outer tube 2 closer to the proximal end than the guidewire port 41, and includes a plurality of joints 22 formed by continuously joining adjacent metal wires 21 in the circumferential direction. In this embodiment, a total of six joints 22a, 22b, 22c, 22d, 22e, and 22f are formed around the entire circumference of the metal coil 2 and in a direction substantially perpendicular to the axial direction of the metal coil 2 in a side view.

[0033] Six joints 22a, 22b, 22c, 22d, 22e, and 22f are provided in the metal coil 2 so that the distance between two adjacent joints gradually increases toward the tip. That is, the distance d2 between joint 22b and its adjacent joint 22c is larger than the distance d1 between joint 22a, which is located closest to the base end, and its adjacent joint 22b. Similarly, the distance d3 between joint 22c and joint 22d is larger than the distance d2 between joint 22b and joint 22c. The distance d4 between joint 22d and joint 22e is larger than the distance d3 between joint 22c and joint 22d. The distance d5 between joint 22e and joint 22f is larger than the distance d4 between joint 22d and joint 22e.

[0034] In the metal coil 2, at locations where joints 22 (22a, 22b, 22c, 22d, 22e, 22f) are formed, where adjacent metal wires 21 are continuously joined in the circumferential direction, the movement of the metal wires 21 is restricted and rigidity is increased. Therefore, by gradually widening the spacing between the joints 22 formed in the metal coil 2 toward the tip, the rigidity of the metal coil 2 can be gradually reduced from the base end toward the tip.

[0035] The method for joining adjacent metal wires 21 to form the joint 22 is not particularly limited, but examples include various welding methods such as laser welding, ultrasonic welding, friction welding, resistance welding, arc welding, electron beam welding, high frequency welding, and plasma welding, as well as brazing with a brazing material and bonding with an adhesive.

[0036] When the axial length of the metal coil 2 is set in the range of 100 to 200 mm, the width of the joints 22 is preferably formed in the range of 0.5 to 2.0 mm. Furthermore, the interval between two adjacent joints 22 may be narrower or wider than the width of the joints 22. However, from the viewpoint of achieving a more excellent gradual change in rigidity, it is desirable that at least one of the intervals between the two adjacent joints 22 is narrower than the width of the joints 22. In particular, it is preferable that the interval between two adjacent joints 22 located closest to the base end of the metal coil 2 is narrower than the width of the two adjacent joints 22 that form the interval. Furthermore, it is more preferable that the interval between two adjacent joints 22 located closest to the base end of the metal coil 2 is narrower than the width of the two adjacent joints 22 that form the interval, and that the interval between two adjacent joints 22 located closest to the tip end of the metal coil 2 is wider than the width of the two adjacent joints 22 that form the interval. The distance between two adjacent joints 22 is preferably in the range of 0.2 to 5.0 mm, for example. In this embodiment, the six joints 22a, 22b, 22c, 22d, 22e, and 22f are formed to have approximately the same width, but this is not limited thereto, and each of the multiple joints 22 may have a different width. For example, gradual change in rigidity can be achieved by forming each of the multiple joints 22 so that the width of the joints 22 narrows from the base end side to the tip end side.

[0037] The metal coil 2 of this embodiment is configured to have a lower rigidity at the tip end than at the base end by providing multiple joints 22a, 22b, 22c, 22d, 22e, and 22f so that the distance between two adjacent joints gradually increases toward the tip end. The configuration for making the rigidity of the metal coil 2 lower at the tip end than at the base end is not limited to this, and for example, the diameter of the metal wires 2 that make up the metal coil 2 may be gradually reduced from the base end to the tip end so that the rigidity at the tip end is lower than at the base end, or multiple joints may be provided at equal intervals and the width of the multiple joints may be gradually reduced from the base end to the tip end so that the rigidity at the tip end is lower than at the base end.

[0038] Furthermore, in the metal coil 2 of this embodiment, the joints 22 are formed around the entire circumference of the metal coil 2 in a direction substantially perpendicular to the axial direction of the metal coil 2 in side view, but this is not limited thereto. As long as adjacent metal wires 21 are joined continuously in the circumferential direction, the joints 22 may be formed in a band shape only in a part of the circumference of the metal coil 2, or may be formed in a direction obliquely intersecting the axial direction of the metal coil 2 in side view. For example, the joints 22 may be joined around the entire circumference substantially perpendicular to the twist angle of the metal coil 2 in side view, or may be joined around the entire circumference substantially parallel to the twist angle of the metal coil 2 in side view. Joining the entire circumference substantially parallel to the twist angle can alleviate stress concentration.

[0039] According to the balloon catheter 10 described above, the metal coil 2, whose distal end is less rigid than its proximal end, is connected to the distal end of the hypotube 1 and disposed at the proximal end inside the outer tube 3. This causes the rigidity of the connection between the high-rigidity metal hypotube 1 and the low-rigidity resin outer tube 3 to decrease from the proximal end to the distal end, effectively eliminating the rigidity gap between the hypotube 1 and the outer tube 3, thereby providing a balloon catheter 10 with excellent pushability. In particular, the balloon catheter 10 has multiple joints 22a, 22b, 22c, 22d, 22e, and 22f such that the spacing between adjacent two joints gradually increases toward the distal end. This allows the metal coil 2, whose distal end is less rigid than its proximal end, to more effectively eliminate the rigidity gap between the hypotube 1 and the outer tube 3.

[0040] Although the use of metal coil 2 alone may not be sufficient to achieve a sufficient gradual change in stiffness from hypotube 1 to metal coil 2, the gradual change in stiffness can be reinforced by providing core wire 8 at the connection between hypotube 1 and metal coil 2. Furthermore, when attempting to achieve a gradual change in stiffness using only core wire 8 without using metal coil 2, a thick wire tends to be required. However, when metal coil 2 and core wire 8 are used together to achieve a gradual change in stiffness, the diameter of core wire 8 can be made smaller than when metal coil 2 is not used, which widens the flow path for the expansion medium and shortens the inflation time.

[0041] The balloon catheter according to the present invention has been described above with reference to the drawings. However, the present invention is not limited to the above embodiment and various modifications are possible. For example, the shape, length, diameter, and other characteristics of the components constituting the balloon catheter may be appropriately designed depending on the intended use and location. Furthermore, a core wire may not be provided inside the balloon catheter, and a reinforcing material other than the core wire, a radiopaque marker, or the like may be provided inside the balloon catheter. Furthermore, the core wire may be provided independently of the purpose of reinforcing the gradual change in rigidity at the connection between the hypotube and the metal coil. For example, the core wire may be connected to the distal end of the metal coil. In this case, the rigidity of the distal end where the metal coil is not provided can be reinforced.

[0042] Alternatively, the metal coil may be connected by wrapping it around the outside of the hypotube. In this case, the distal end of the hypotube may be cut at an angle. Specifically, as shown in FIG. 3(a), a hypotube 1A with a diagonally cut distal end may be wrapped around a metal coil 2 (joint 22 not shown) from the outside, resulting in a configuration as shown in FIG. 3(b). This configuration can further reduce the rigidity gap. Cutting the distal end of the hypotube 1A at an angle results in a curved change in the rigidity of the hypotube 1A toward the distal end. However, by wrapping the distal end of the diagonally cut hypotube 1A with the metal coil 2, the rigidity can be made closer to a linear value. Furthermore, the wrapping configuration with the metal coil 2 as described above can further improve kink resistance.

[0043] While the above embodiment has been described assuming that the balloon catheter is a rapid exchange type balloon catheter, the present invention can also be applied to an over-the-wire type balloon catheter in which a guidewire is inserted from the proximal end of the hypotube and extends into the hypotube and metal coil. In such a case, an inner tube through which the guidewire is inserted is disposed inside the outer tube and hypotube, and the proximal end of the inner tube is connected to a guidewire port provided on the proximal end of the hypotube. [Explanation of symbols]

[0044] 10 Balloon catheter 1,1A hypotube (proximal tube) 2 Metal coil (coil material) 21 Metal wire 22a, 22b, 22c, 22d, 22e, 22f joints 3 outer tube 4 inner tubes 41 Guidewire port 5. Balloon 51 Extension 52 Tip mounting part 53 Base end mounting part 6 Tip 7 Connectors 8 Core Wire

Claims

1. a metal proximal tube; a coil member attached to the distal end side of the base end tube and formed by winding at least one metal wire in a spiral shape; an outer tube made of resin connected to the distal end side of the base end tube so as to cover the coil member; a balloon connected to the distal end side of the outer tube, the rigidity of the distal end side of the coil member is lower than that of the proximal end side; the coil member has a plurality of joints in which adjacent metal wires are joined continuously in the circumferential direction, and the interval between two adjacent joints gradually increases toward the tip end, A balloon catheter, wherein the joint is formed around the entire circumference of the coil member.

2. an inner tube disposed inside the outer tube and through which a guide wire is inserted; a guidewire port formed at a portion where a proximal end of the inner tube is joined to the outer tube, The balloon catheter according to claim 1 , wherein the coil member is disposed on the outer tube on the proximal side of the guidewire port.

3. an inner tube disposed inside the outer tube and through which a guide wire is inserted; a guidewire port formed on the proximal side of the proximal tube, The balloon catheter according to claim 1 , wherein the inner tube extends from the guidewire port into the proximal tube and the coil member.

4. 4. The balloon catheter according to claim 1, wherein the cross section of the metal wire constituting the coil member is substantially rectangular.

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