Catheter

Abstract

This catheter includes an inner tube, a core wire, and an outer tube. The inner tube has a lumen. The core wire is positioned further toward the outside than the inner tube in the radial direction of the inner tube. The outer tube surrounds the inner tube and the core wire. In a cross section of the catheter, the position of the centroid of a region occupied by the core wire is different from the position of the centroid of a region defined by the outer edge of the outer tube. The outer tube has a first layer and a second layer. The second layer is positioned further toward the outside than the first layer in the radial direction of the outer tube. The melting point of the second layer is lower than the melting point of the first layer.

Description

Catheter

[0001] The technology disclosed in this specification relates to a catheter.

[0002] The catheter is used, for example, when treating a lesion in a living body lumen such as a blood vessel or a digestive organ. The catheter has an inner tube and an outer tube surrounding the inner tube.

[0003] For example, in order to improve the breaking strength of the catheter, a long core wire is disposed inside the catheter (see, for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2022-175116

[0005] In a known catheter, a configuration in which the core wire is eccentrically arranged (hereinafter referred to as a "core eccentricity configuration") may be adopted. The core eccentricity configuration is a configuration in which, in the cross section of the catheter, the position of the center of gravity of the region occupied by the core wire is different from the position of the center of gravity of the region defined by the outer edge of the outer tube. When a catheter adopting the core eccentricity configuration is subjected to a thermal load, it bends due to the difference in the coefficient of thermal expansion between the core wire (for example, metal) and the outer tube (for example, resin).

[0006] This specification discloses a technology capable of solving the above-described problems.

[0007] The technology disclosed in this specification can be realized, for example, in the following forms.

[0008] The catheter disclosed in this embodiment includes an inner tube, a core wire, and an outer tube. The inner tube has a lumen. The core wire is located outside the inner tube in the radial direction of the inner tube. The outer tube surrounds the inner tube and the core wire. In the cross section of the catheter, the position of the center of gravity of the region occupied by the core wire is different from the position of the center of gravity of the region defined by the outer edge of the outer tube. The outer tube has a first layer and a second layer. The second layer is located outside the first layer in the radial direction of the outer tube. The melting point of the second layer is lower than the melting point of the first layer.

[0009] Side view of the catheter in this embodiment. Explanatory diagram showing a longitudinal section of the tip of the catheter. Explanatory diagram showing a cross-section of the catheter at position III-III in Figure 2.

[0010] (Embodiment) (Configuration of Catheter 10) Figure 1 is a side view of the catheter 10 in this embodiment. Figure 2 is an explanatory diagram showing a longitudinal section (YZ section) of the tip of the catheter 10 in this embodiment. Figure 3 is an explanatory diagram showing a cross section (XY section) of the catheter 10 in this embodiment at position III-III in Figure 2.

[0011] The positive Z-axis side of the catheter 10 is the distal end (tip) that is inserted into the body. The negative Z-axis side of the catheter 10 is the proximal end (proximal) that is manipulated by a physician or other technician. In the catheter 10 and its components, "tip" means the end on the tip side, "tip portion" means the tip and its vicinity, "proximal end" means the end on the proximal side, and "proximal end portion" means the proximal end and its vicinity. In the catheter 10 and its components, "longitudinal section" means a section parallel to the central axis Ax of the catheter 10, and "transverse section" means a section perpendicular to the central axis Ax of the catheter 10.

[0012] Catheter 10 is a tubular medical device with an open tip and a proximal end. Catheter 10 is used, for example, to treat lesions in biological lumens. Biological lumens include blood vessels, the digestive tract, ureters, organs, and bile ducts.

[0013] The catheter 10 has a shaft portion 20 and a connector 30.

[0014] The connector 30 is a component that constitutes the proximal end of the catheter 10. The connector 30 is connected to the proximal end of the shaft portion 20. The connector 30 is formed of, for example, resin.

[0015] The shaft portion 20 is an elongated member extending in the longitudinal direction of the catheter 10. The shaft portion 20 has a first lumen 11L and a second lumen 12L that extend in the longitudinal direction of the shaft portion 20. For example, other medical devices are inserted into the first lumen 11L and the second lumen 12L. The position of the tip 20d of the shaft portion 20 is the same as the position of the tip 10d of the catheter 10. The base end of the shaft portion 20 is connected to the tip of the connector 30.

[0016] The shaft portion 20 includes a tip 150, a first inner tube 111, a second inner tube 112, an outer tube 140, a core wire 160, and a marker 170. For the sake of explanation, the first inner tube 111 and the second inner tube 112 may be collectively referred to as inner tubes 111 and 112 below.

[0017] The tip 150 is a tubular member having a through hole 156 formed in it that extends in the longitudinal direction of the shaft portion 20. The tip 150 is positioned at the very front of the shaft portion 20. The through hole 156 of the tip 150 forms the tip of the first lumen 11L. The tip 150 is made of, for example, resin or metal.

[0018] The first inner tube 111 is a tubular member having a through hole 119 formed in the longitudinal direction of the shaft portion 20. The shape of the outer edge of the cross-section of the first inner tube 111 is, for example, approximately circular. The shape of the outer edge of the cross-section may differ for each part of the first inner tube 111. The first inner tube 111 extends from the tip of the shaft portion 20 to the middle portion of the shaft portion 20. More specifically, the tip of the first inner tube 111 is inserted into the hollow portion of the base end of the tip 150. The base end of the first inner tube 111 is connected to a notch 19 formed in the middle portion of the catheter 10 (the portion between the tip and base end of the catheter 10). The through hole 119 formed in the first inner tube 111 is connected to a through hole 156 formed in the tip 150. The first lumen 11L is formed by a through hole 119 formed in the first inner tube 111 and a through hole 156 formed in the tip 150. In other words, the first inner tube 111 has a portion of the first lumen 11L. The first lumen 11L extends from the tip of the shaft portion 20 to the middle portion of the shaft portion 20. More specifically, the position of the tip 11Ld of the first lumen 11L is the same as the position of the tip 20d of the shaft portion 20. The proximal end 11Lp of the first lumen 11L is connected to a notch 19 formed in the middle portion of the catheter 10 (the portion between the tip and proximal end of the catheter 10).

[0019] The second inner tube 112 is a tubular member having a through hole 115 formed in it that extends in the direction of the long axis of the shaft portion 20. The shape of the outer edge of the cross-section of the second inner tube 112 is, for example, substantially circular. The shape of the outer edge of the cross-section may differ for each part of the second inner tube 112. The second inner tube 112 extends from the tip of the shaft portion 20 to the base of the shaft portion 20. More specifically, the position of the tip 112d of the second inner tube 112 is equal to at least one of the position on the base side of the base end 150p of the tip tip 150 and the position of the base end 150p of the tip tip 150. The position of the tip 112d of the second inner tube 112 is on the tip side of the middle portion of the catheter 10. The position of the base end 112p of the second inner tube 112 is substantially the same as the position of the base end 20p of the shaft portion 20. The second lumen 12L is formed by the through hole 115. In other words, the second inner tube 112 has the second lumen 12L. The second lumen 12L extends from the tip of the shaft portion 20 to the base of the shaft portion 20. More specifically, the position of the tip 12Ld of the second lumen 12L is equal to at least one of the positions of the base end 150p of the tip tip 150 and the position of the base end 150p of the tip tip 150. The position of the tip 12Ld of the second lumen 12L is on the tip side of the middle portion of the catheter 10. The position of the base end 12Lp of the second lumen 12L is approximately the same as the position of the base end 20p of the shaft portion 20.

[0020] The inner tubes 111 and 112 are formed from, for example, a resin material. Examples of materials for forming the inner tubes 111 and 112 include polyamide resins, polyurethane resins, and polyolefin resins. The inner tubes 111 and 112 may be formed from the same material throughout. The inner tubes 111 and 112 may be formed from different materials in different parts. In this embodiment, the inner tubes 111 and 112 are formed from a polyamide elastomer.

[0021] The outer tube 140 is a tubular member with an open tip and base. The shape of the outer edge of the cross-section of the outer tube 140 is, for example, approximately elliptical. The shape of the outer edge of the cross-section may differ for each part of the outer tube 140. The outer tube 140 surrounds the inner tubes 111 and 112. In other words, the inner tubes 111 and 112 are housed in the hollow portion of the outer tube 140.

[0022] The outer tube 140 extends from the tip of the shaft portion 20 to the base end of the shaft portion 20. More specifically, the position of the tip 140d of the outer tube 140 is approximately the same as the position of the base end 150p of the tip 150. The position of the base end 140p of the outer tube 140 is approximately the same as the position of the base end 20p of the shaft portion 20.

[0023] The outer tube 140 is formed from, for example, a resin material. Examples of materials for forming the outer tube 140 include polyamide resins, polyurethane resins, and polyolefin resins. The outer tube 140 may be formed from the same material throughout. The outer tube 140 may be formed from different materials in different parts. In this embodiment, the outer tube 140 is formed from a polyamide elastomer.

[0024] The core wire 160 is an elongated member extending in the longitudinal direction of the catheter 10. The core wire 160 is located radially outside the inner tubes 111 and 112 and is surrounded by the outer tube 140. In other words, the core wire 160 is housed outside the inner tubes 111 and 112 within the hollow portion of the outer tube 140. The core wire 160 extends from the tip of the catheter 10 to the proximal end of the catheter 10. More specifically, the position of the tip 160d of the core wire 160 is proximal to the tip 20d of the shaft portion 20, proximal to the tip 111d of the first inner tube 111, and proximal to the proximal end 150p of the tip tip 150. The position of the proximal end 160p of the core wire 160 is proximal to the proximal end 20p of the shaft portion 20. The outer edge of the cross-section of the core wire 160 is, for example, approximately circular. The outer edge of the cross-section may differ for each part of the core wire 160.

[0025] As shown in Figure 3, the catheter 10 of this embodiment employs a configuration in which the core wire 160 is eccentrically positioned (core eccentric configuration). In the core eccentric configuration, the position of the center of gravity G1 of the region occupied by the core wire 160 in the cross-section of the catheter 10 is different from the position of the center of gravity G2 of the region defined by the outer edge of the outer tube 140. In the catheter 10 of this embodiment, the catheter 10 has only one core wire 160, and the core wire 160 is positioned eccentrically toward the positive X-axis direction from the central axis Ax of the catheter 10. Therefore, the core eccentric configuration is realized.

[0026] The core wire 160 is formed of, for example, a metal. Examples of materials for forming the core wire 160 include stainless steel (e.g., SUS302, SUS304, SUS316, etc.), Ni-Ti alloy, nickel-chromium alloy, cobalt alloy, tungsten, etc. The core wire 160 may be formed of the same material throughout. The core wire 160 may be formed of different materials in different parts.

[0027] The marker 170 is a cylindrical member positioned at the tip of the catheter 10. The marker 170 is positioned, for example, at the base of the tip 150, surrounding the first inner tube 111 from the outside. The marker 170 is made of a radiopaque material (e.g., an X-ray opaque material). Examples of radiopaque materials include platinum, gold, silver, tin, tungsten, bismuth, rhenium, tantalum, palladium, iridium, barium, and their alloys.

[0028] (Detailed configuration of catheter 10) The outer tube 140 of this embodiment has a first layer 141 and a second layer 142. The first layer 141 surrounds the inner tubes 111, 112 and the core wire 160. In this embodiment, the inner circumferential surface of the first layer 141 is in contact with the outer circumferential surfaces of the inner tubes 111, 112 and the outer circumferential surface of the core wire 160. In this embodiment, a space 60 exists in the region surrounded by the first layer 141. The space 60 of this embodiment includes space 61, space 62, space 63 and space 64. Space 61 is the space surrounded by the first inner tube 111, the core wire 160 and the first layer 141. Space 62 is the space surrounded by the second inner tube 112, the core wire 160 and the first layer 141. Space 63 is the space surrounded by the first inner tube 111, the second inner tube 112, and the core wire 160. Space 64 is the space surrounded by the first inner tube 111, the second inner tube 112, and the first layer 141. Each space 60 extends, for example, from the tip to the proximal end of the catheter 10.

[0029] The second layer 142 of the outer tube 140 is located outside the first layer 141 in the radial direction of the outer tube 140. The second layer 142 surrounds the first layer 141 in the cross-section of the outer tube 140. In this embodiment, the inner circumferential surface of the second layer 142 is in contact with the outer circumferential surface of the first layer 141.

[0030] The melting point of the second layer 142 is lower than that of the first layer 141. The melting point of the second layer 142 is also lower than that of the inner tubes 111 and 112. The difference between the melting points of the first layer 141 and the second layer 142 is, for example, 2°C or more and 200°C or less. The above difference may be 10°C or more and 200°C or less. The smaller the above difference, the more difficult it becomes to achieve a state in which the second layer 142 is melted and the first layer 141 is not melted. The larger the above difference, the higher the hardness of the first layer 141 becomes, making it difficult to give the shaft portion 20 sufficient flexibility. Such a relationship between the melting points of the first layer 141 and the second layer 142 can be achieved by appropriately selecting the forming materials for the first layer 141 and the second layer 142.

[0031] In the cross-section of the catheter 10 of this embodiment, the outer surface of the core wire 160 has a portion that contacts surfaces other than the first layer 141. Specifically, the outer surface of the core wire 160 has a portion that contacts the inner tubes 111, 112 and the space 60. The angle θ of the portion of the core wire 160 that contacts the first layer 141 over the entire outer circumference (360 degrees) is, for example, 10 degrees or more and 350 degrees or less. The above angle θ may also be 40 degrees or more and 320 degrees or less, or 100 degrees or more and 260 degrees or less. The smaller the above angle θ, the larger the space 60 becomes, which increases the effect of suppressing the core wire 160 from adhering to the first layer 141, but the outer diameter of the shaft portion 20 becomes larger. The larger the above angle θ, the smaller the space 60 becomes, which decreases the outer diameter of the shaft portion 20, but the effect of suppressing the core wire 160 from adhering to the first layer 141 becomes smaller.

[0032] (Method for manufacturing catheter 10) The catheter 10 is formed, for example, by the following method. First, the worker prepares inner tubes 111, 112 and core wire 160. Next, the worker covers the inner tubes 111, 112 and core wire 160 with the first layer 141 of the outer tube 140. At this time, the worker ensures a space 60 between the first layer 141 and the inner tubes 111, 112 and core wire 160. Next, the worker covers the first layer 141 with the second layer 142 of the outer tube 140. Next, the worker welds the inner tubes 111, 112 and the outer tube 140 at a welding temperature higher than the melting point of the second layer 142 and lower than the melting points of the first layer 141 and the inner tubes 111, 112. As a result, the first layer 141 and inner tubes 111, 112 do not melt, while the second layer 142 melts. The molten second layer 142 integrates each component of the catheter 10. Since the first layer 141 does not melt, the space 60 that was secured between the first layer 141 and the inner tubes 111, 112 and the core wire 160 before welding remains after welding. As a result, the relative movement of the core wire 160 with respect to the first layer 141 is less restricted by the first layer 141.

[0033] To more reliably form the space 60, the worker may insert a long core between the first layer 141 and the inner tubes 111 and 112 before welding. After welding, the worker removes the core to ensure the space 60 is formed. According to the above configuration and manufacturing method, even if the core wire 160 adheres to the first layer 141 after welding, the worker can easily separate the first layer 141 and the core wire 160 by lightly pulling both ends of the catheter 10. This makes it possible to suppress the bending of the catheter 10 (shaft portion 20) caused by the difference in thermal expansion coefficients between the outer tube 140 and the core wire 160.

[0034] (Effects of this embodiment) As described above, the catheter 10 of this embodiment includes inner tubes 111, 112, a core wire 160, and an outer tube 140. The inner tubes 111, 112 have lumens. The core wire 160 is located outside the inner tubes 111, 112 in the radial direction. The outer tube 140 surrounds the inner tubes 111, 112 and the core wire 160. In the cross-section of the catheter 10, the position of the center of gravity G1 of the region occupied by the core wire 160 is different from the position of the center of gravity G2 of the region defined by the outer edge of the outer tube 140. The outer tube 140 has a first layer 141 and a second layer 142. The second layer 142 is located outside the first layer 141 in the radial direction of the outer tube 140. The melting point of the second layer 142 is lower than the melting point of the first layer 141. In the catheter 10 of this embodiment, welding is performed at a welding temperature higher than the melting point of the second layer 142 and lower than the melting point of the first layer 141, thereby preventing the core wire 160 from being embedded in or adhering to the first layer 141. As a result, the relative movement of the core wire 160 with respect to the first layer 141 is less restricted by the first layer 141. Therefore, even in a catheter 10 that includes a core wire 160 with eccentric characteristics, the bending of the catheter 10 caused by the difference in thermal expansion coefficients between the core wire 160 and the first layer 141 is suppressed.

[0035] In this embodiment, in the cross-section of the catheter 10, the outer surface of the core wire 160 has a portion that is in contact with a surface other than the first layer 141. Therefore, the relative movement of the core wire 160 with respect to the first layer 141 is less restricted by the first layer 141, and the bending of the catheter 10 caused by the difference in thermal expansion coefficients between the core wire 160 and the first layer 141 is effectively suppressed.

[0036] In this embodiment, in the cross-section of the catheter 10, the outer surface of the core wire 160 has a portion that is in contact with the space 60. Therefore, the relative movement of the core wire 160 with respect to the first layer 141 is less restricted by the first layer 141, and the bending of the catheter 10 caused by the difference in thermal expansion coefficients between the core wire 160 and the first layer 141 is suppressed more effectively.

[0037] In this embodiment, the inner tubes 111 and 112 include a first inner tube 111 and a second inner tube 112. The first inner tube 111 has a first lumen 11L. The second inner tube 112 has a second lumen 12L. The outer tube 140 surrounds the first inner tube 111, the second inner tube 112, and the core wire 160. According to this embodiment, curvature of the catheter 10 having two lumens is suppressed.

[0038] In the catheter 10 of this embodiment, the position of the tip 11Ld of the first lumen 11L is equal to the position of the tip 10d of the catheter 10 in the longitudinal direction of the catheter 10. The position of the proximal end 11Lp of the first lumen 11L is in the middle of the catheter 10 in the longitudinal direction of the catheter 10. According to this embodiment, the operator can use the first lumen 11L as a rapid replacement lumen.

[0039] In the catheter 10 of this embodiment, the position of the tip 12Ld of the second lumen 12L is towards the tip of the catheter 10 in the longitudinal direction of the catheter 10, relative to the middle of the catheter 10. The position of the proximal end 12Lp of the second lumen 12L is equal to the position of the proximal end 140p of the outer tube 140 in the longitudinal direction of the catheter 10. According to this embodiment, the operator can use the second lumen 12L as an over-the-wire lumen.

[0040] In the catheter 10 of this embodiment, the tip 160d of the core wire 160 is located further forward than the tip 140d of the outer tube 140. According to the catheter 10 of this embodiment, the strength of the tip of the catheter 10 is improved.

[0041] (Modified Example) The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the gist thereof. For example, the following modifications are also possible.

[0042] In the above embodiments, the inner tubes 111 and 112 may be formed of a single layer made of one material, or may be formed of a plurality of layers made of different materials from each other. In the above embodiments, there may be other layers on the inner and outer sides of the inner tubes 111 and 112, and on the inner and outer sides of the outer tube 140.

[0043] In the above embodiments, in the cross section of the catheter 10, the outer peripheral surface of the core wire 160 does not have to contact the outer peripheral surfaces of the inner tubes 111 and 112. The outer peripheral surface of the core wire 160 does not have to contact the inner peripheral surface of the first layer 141.

[0044] In the above embodiments, the catheter 10 does not have to have the space 60. In the above embodiments, the catheter 10 may have a space 60 that does not contact the outer peripheral surface of the core wire 160, such as the space 64 between the first inner tube 111, the second inner tube 112, and the first layer 141.

[0045] In the cross section of the catheter 10 of the above embodiments, the number of the inner tubes 111 and 112, the core wire 160, and the space 60 included in the outer tube 140 may be one or a plurality. The technology disclosed in this specification is not limited to a catheter having two lumens, and can be similarly applied to a catheter having one lumen or a catheter having three or more lumens.

[0046] In the above embodiments, the position of the proximal end 11Lp of the first lumen 11L does not have to be in the middle part of the catheter 10. In the above embodiments, the position of the distal end 160d of the core wire 160 may be on the proximal side of the proximal end 150p of the tip chip 150.

[0047] In the above-described embodiment, a reinforcing member may be embedded inside the inner tubes 111 and 112. The reinforcing member may be formed, for example, by a braided body in which a plurality of strands are braided so as to cross each other. The reinforcing member may be formed by a coil. The reinforcing member may be continuously arranged from the proximal end to the distal end of the inner tubes 111 and 112.

[0048] In the above-described embodiment, the wall thicknesses of the inner tubes 111 and 112, the wall thickness of the outer tube 140, and the diameter of the core wire 160 may vary over the entire length in the long axis direction of the catheter 10.

[0049] The cross-sectional shapes of the catheter 10, the inner tubes 111 and 112, the outer tube 140, and the core wire 160 of the above-described embodiment can be arbitrarily set, and are, for example, circular, partially circular, elliptical, rectangular, parallelogram, trapezoidal, rhombic, etc. The cross-sectional shapes may be different for each part of the catheter 10, the inner tubes 111 and 112, the outer tube 140, and the core wire 160.

[0050] The materials of the respective members in the catheter 10 of the above-described embodiment are merely examples and can be variously deformed.

Claims

1. A catheter (10) comprising: an inner tube (111, 112) having lumens; a core wire (160) located outside the inner tube (111, 112) in the radial direction of the inner tube (111, 112); and an outer tube (140) surrounding the inner tube (111, 112) and the core wire (160), wherein in a cross-section of the catheter (10), the position of the center of gravity (G1) of the region occupied by the core wire (160) is different from the position of the center of gravity (G2) of the region defined by the outer edge of the outer tube (140); and the outer tube (140) includes a first layer (141) and a second layer (142) located outside the first layer (141) in the radial direction of the outer tube (140) and having a lower melting point than the first layer (141).

2. A catheter (10) according to claim 1, wherein in a cross-section of the catheter (10), the outer surface of the core wire (160) has a portion that is in contact with a surface other than the first layer (141).

3. A catheter (10) according to claim 2, wherein in a cross-section of the catheter (10), the outer surface of the core wire (160) has a portion that is in contact with the space (60).

4. A catheter (10) according to any one of claims 1 to 3, wherein the inner tubes (111, 112) include a first inner tube (111) having a first lumen (11L) and a second inner tube (112) having a second lumen (12L), and the outer tube (140) surrounds the first inner tube (111), the second inner tube (112), and the core wire (160).

5. A catheter (10) according to claim 4, wherein the position of the tip (11Ld) of the first lumen (11L) is equal to the position of the tip (10d) of the catheter (10) in the longitudinal direction of the catheter (10), and the position of the proximal end (11Lp) of the first lumen (11L) is in the middle of the catheter (10) in the longitudinal direction of the catheter (10).

6. A catheter (10) according to claim 5, wherein the position of the tip (12Ld) of the second lumen (12L) is toward the tip of the catheter (10) in the longitudinal direction of the catheter (10), and the position of the proximal end (12Lp) of the second lumen (12L) is equal to the position of the proximal end (140p) of the outer tube (140) in the longitudinal direction of the catheter (10).

7. A catheter (10) according to any one of claims 1 to 6, wherein the position of the tip (160d) of the core wire (160) is more distal to the tip (140d) of the outer tube (140).

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