Catheter

Abstract

A catheter 1 is provided with: a shaft 2 having a lumen 8; a core wire 12 housed in the lumen 8; and a torque transmission agent 14 filled in a space between the inner peripheral surface of the shaft 2 and the outer peripheral surface of the core wire 12 in the lumen 8, wherein the torque transmission agent 14 has viscosity or viscoelasticity, and transmits, to the core wire 12, torque inputted to the shaft 2.

Description

Catheter

[0009] , , ,

[0010]

[0001] The present disclosure relates to a catheter.

[0002] Conventionally, catheters for electrophysiological detection have been known. This catheter is also called an EP catheter and is used, for example, when diagnosing the cause of arrhythmia. The EP catheter is required to be able to operate the orientation of the tip side with high precision in order to pass through the thin blood vessels of the heart. On the other hand, for example, in Patent Document 1, a guide wire type electrode catheter is disclosed in which a core wire is inserted into a tube, and the torsional rigidity of the tube and the torsional rigidity of the core wire are complemented to improve the rotational transmissibility from the proximal end side to the distal end side of the tube.

[0003] Japanese Patent Application Laid-Open No. 2021-27974

[0004] The present inventor has intensively studied the above-described conventional catheter and has come to recognize that there is room to further improve the torque transmissibility from the proximal end side to the distal end side of the conventional catheter to further improve the operability of the catheter.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a technique for improving the operability of a catheter.

[0006] One aspect of the present disclosure is a catheter. This catheter includes a shaft having a lumen, a core wire accommodated in the lumen, and a torque transmission agent that is filled in a space between the inner peripheral surface of the shaft and the outer peripheral surface of the core wire in the lumen, has viscosity or viscoelasticity, and transmits torque input to the shaft to the core wire.

[0007] Any combination of the above components, and those obtained by converting the expression of the present disclosure among methods, devices, systems, etc. are also effective as aspects of the present disclosure.

[0008] According to the present disclosure, the operability of the catheter can be improved.

[0009] It is a side view of the catheter according to the embodiment. It is a cross-sectional view taken along line A-A in FIG. 1.

[0010] The present disclosure will be described below with reference to the drawings, based on preferred embodiments. The embodiments are illustrative and not limiting, and not all features or combinations thereof described in the embodiments are necessarily essential to the present disclosure. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and redundant descriptions are omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and are not to be interpreted restrictively unless otherwise specified. Furthermore, where terms such as "first," "second," etc. are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are used to distinguish one configuration from another. In addition, some components that are not important for explaining the embodiments are omitted in each drawing.

[0011] Figure 1 is a side view of a catheter 1 according to an embodiment. Catheter 1 is an EP catheter used, for example, to diagnose arrhythmias in the heart. Catheter 1 may be used for other purposes. Catheter 1 comprises a shaft 2, an electrode 4, and a connector 6.

[0012] The shaft 2 is composed of a long, flexible tube, with at least its tip inserted into the body. The shaft 2 can be made of a known flexible material, including resins such as polyolefins, polytetrafluoroethylenes, polyether block amides, and polyamides. The length of the shaft 2 may be, for example, 1000 mm to 3000 mm or 1300 mm to 2000 mm. The diameter of the shaft 2 may be 3 Fr or less, 2 Fr or less, or 1 Fr or less. In this disclosure, "diameter of the shaft 2" means the diameter of the widest part of the shaft 2.

[0013] The electrodes 4 are positioned at the tip of the shaft 2, that is, in the portion of the shaft 2 that is inserted into the body. For example, the shaft 2 may have six electrodes 4. The multiple electrodes 4 are arranged in the longitudinal direction of the shaft 2 with spaces between them. One of the electrodes 4 is fitted into the tip of the shaft 2. The remaining electrodes 4 are fitted into the circumferential surface of the shaft 2.

[0014] Connector 6 is located on the proximal end of shaft 2. The proximal end of shaft 2 is connected to connector 6. Connector 6 is positioned outside the body when catheter 1 is in use and is grasped or manipulated by the user. An external power supply (not shown) is also connected to connector 6.

[0015] Figure 2 is a cross-sectional view along the line A-A in Figure 1. The shaft 2 has a lumen 8 inside. For example, the lumen 8 extends from the tip to the base of the shaft 2. The catheter 1 also comprises a conductor 10, a core wire 12, and a torque transmission agent 14.

[0016] The conductor 10, core wire 12, and torque transmission agent 14 are housed in the lumen 8. The tip end of the conductor 10 is electrically connected to the electrode 4, and the base end is electrically connected to an external power supply via a connector 6. Multiple conductors 10 corresponding to each electrode 4 are inserted into the lumen 8, but only one conductor 10 is shown in Figure 2, and the other conductors 10 are not shown. The circumferential surface of each conductor 10 is covered with an insulating coating 16.

[0017] The core wire 12 can be made of resins such as polyolefin, polytetrafluoroethylene, polyether block amide, polyamide, and polyether ether ketone, or metals such as stainless steel and nitinol. The core wire 12 has higher rigidity than the shaft 2. When the user of the catheter 1 applies a force, i.e., torque, to the shaft 2, the core wire 12 transmits the torque from the input point to the tip of the shaft 2. The core wire 12 also transmits a force, when the user applies a force, in the longitudinal direction of the shaft 2, from the input point to the tip of the shaft 2. The tip end of the core wire 12 is fixed to the inner surface of the shaft 2 with an adhesive or the like. The proximal end of the core wire 12 is fixed to the connector 6 with an adhesive or the like. The adhesive that fixes the proximal end of the core wire 12 to the connector 6 can also fix the proximal end of the core wire 12 to the proximal end of the shaft 2. The core wire 12 is sealed inside the lumen 8.

[0018] The torque transmission agent 14 is filled into the space between the inner circumferential surface of the shaft 2 and the outer circumferential surface of the core wire 12 within the lumen 8. The torque transmission agent 14 is sealed within the lumen 8. In this embodiment, the lumen 8 is sealed from the outside of the shaft 2. This prevents the torque transmission agent 14 from leaking out of the lumen 8. As an example, the lumen 8 is provided independently of a fluid delivery lumen for circulating contrast agents, etc., and a lumen for inserting instruments such as guide wires. The torque transmission agent 14 has viscosity or viscoelasticity and transmits the torque input to the shaft 2 to the core wire 12. The torque transmission agent 14 may be a gel at 25°C, or it may be a liquid with a viscosity greater than 0.89 mPa·S at 25°C. If the torque transmission agent 14 is a gel, it may be a liquid before filling the lumen 8 and gel after filling the lumen 8. If the torque transmission agent 14 is a liquid, it has a higher viscosity than physiological saline at 25°C. Examples of torque transmission agents 14 include acrylic polymers and silicone polymers.

[0019] Furthermore, in both cases where the torque transmission agent 14 is a gel at 25°C and a liquid that satisfies the viscosity conditions described above, the viscosity of the torque transmission agent 14 may be 150,000 mPa·s or less at 25°C. This makes it easier to fill the lumen 8 with the torque transmission agent 14. Also, the viscosity of the torque transmission agent 14 may be 400 mPa·s or more and 5,000 mPa·s or less at 25°C. In addition, the penetration depth of the torque transmission agent 14 calculated in accordance with ISO 2137 may be 13 mm / 10 or more, for example, 90 mm / 10.

[0020] The torque transmission agent 14 may be filled in all or part of the range from the base end of the electrode 4 located at the most proximal end to a position 10 mm from the base end of the shaft 2. Alternatively, the torque transmission agent 14 may be filled in the entire range from the base end of the electrode 4 located at the most proximal end to the base end of the shaft 2, or it may be filled in the entire range from the tip to the base end of the shaft 2. Furthermore, when the total length of the shaft 2 is divided into five equal regions, the amount of torque transmission agent 14 filled in the region including the tip of the shaft 2, i.e., the outermost region, may be greater than the amount of torque transmission agent 14 filled in the region including the base end of the shaft 2, i.e., the most proximal region. The amount of torque transmission agent 14 filled in each region is the average value of the amount of torque transmission agent 14 filled in a cross section perpendicular to the axial direction of the shaft 2, measured at five predetermined points offset in the axial direction of the shaft 2 within each region. The five predetermined points are the points that coincide with the boundaries of adjacent sub-regions when each region is divided into six equal parts in the axial direction of the shaft 2.

[0021] As described above, the proximal end of the core wire 12 is fixed to the connector 6. Therefore, when a user grasps the connector 6 and rotates the catheter 1 to change the orientation of the catheter 1 or the tip of the shaft 2, that is, when torque is applied to the connector 6, the torque can be directly transmitted to the core wire 12. Thus, the applied torque can be transmitted more reliably to the tip of the shaft 2 via the core wire 12. As a result, the orientation of the tip of the shaft 2 can be manipulated with high precision.

[0022] However, because the shaft 2 is long, the connector 6 is not always within the user's reach during catheter 1 use. When the connector 6 is located away from the user, the user may grasp and rotate the shaft 2, that is, directly apply torque to the area of ​​the shaft 2 excluding the tip and proximal ends (hereinafter, this area will be referred to as the intermediate section). In the intermediate section of the shaft 2, the shaft 2 and the core wire 12 are not fixed to each other. Therefore, if the lumen 8 is not filled with torque transmission agent 14, the torque applied to the intermediate section of the shaft 2 may not be sufficiently transmitted to the core wire 12, and the direction of the tip of the shaft 2 may not be able to be controlled with high precision. Furthermore, since the core wire 12 is housed within the lumen 8, the user cannot directly apply torque to the core wire 12.

[0023] In contrast, in the catheter 1 of this embodiment, a torque transmission agent 14 is filled in the lumen 8. The torque transmission agent 14 fills the gap between the inner surface of the shaft 2 and the outer surface of the core wire 12, allowing torque input to the middle part of the shaft 2 to be transmitted to the core wire 12 via the torque transmission agent 14. This makes it easier to transmit the torque to the tip of the shaft 2. Therefore, the operability of the catheter 1 can be improved. In addition, the user can grasp the shaft 2 and manipulate the direction of the tip of the shaft 2. Therefore, the catheter 1 can be given an operating sensation as if it were operating a guide wire.

[0024] In particular, when the shaft 2 is composed of a small-diameter tube of 3Fr or less, the torque transmission performance from the base end to the tip end of the shaft 2 tends to decrease. Therefore, the effect of improving torque transmission performance by filling with torque transmission agent 14 is particularly effective in shafts 2 with a diameter of 3Fr or less.

[0025] Furthermore, increasing the diameter of the core wire 12 is expected to improve torque transmission from the base end to the tip end of the shaft 2. It is also conceivable to omit the shaft 2 and allow the user to directly operate the core wire 12. However, in these cases, drawbacks may arise, such as a reduction in the space available for inserting the conductor 10 within the lumen 8, requiring a larger diameter for the shaft 2, or making it difficult to mount the electrodes 4 and conductor 10.

[0026] Alternatively, to facilitate the transmission of torque applied to the shaft 2 to the core wire 12, it is conceivable to fill the lumen 8 with adhesive and fix the shaft 2 and the core wire 12 along the entire longitudinal direction of the shaft 2. However, in this case, there is a risk that the adhesive between the shaft 2 and the core wire 12 may detach when the shaft 2 bends. Once the adhesive detaches, it cannot be restored, and the effect of improving torque transmission by filling with adhesive is lost.

[0027] In contrast, in the catheter 1 of this embodiment, a torque transmission agent 14 having viscosity or viscoelasticity is filled into the lumen 8. The torque transmission agent 14 maintains wettability within the lumen 8 and can follow the deformation of the shaft 2 even when the shaft 2 is bent. Therefore, a state in which torque can be easily transmitted from the shaft 2 to the core wire 12 can be maintained. Thus, the operability of the catheter 1 can be improved more stably.

[0028] In this embodiment of the catheter 1, the number of electrodes 4 and conductors 10 is not particularly limited. The electrodes 4 and conductors 10 may be omitted. The core wire 12 and the conductors 10 may be inserted into separate lumens. In other words, the conductors 10 do not have to be inserted into the lumen 8 through which the core wire 12 is inserted. The core wire 12 may be solid or hollow.

[0029] The embodiments of this disclosure have been described in detail above. The embodiments described above are merely examples of how to implement this disclosure. The content of the embodiments does not limit the technical scope of this disclosure, and many design changes, such as changes, additions, and deletions of components, are possible as long as they do not deviate from the concept of this disclosure as defined in the claims. A new embodiment with design changes will have the effects of both the combined embodiment and the variation. In the embodiments described above, the content in which such design changes are possible is emphasized with notations such as "of this embodiment" or "in this embodiment," but design changes are also permitted even if there are no such notations. Any combination of components included in each embodiment is also valid as an embodiment of this disclosure. The hatching applied to the cross-section in the drawings does not limit the material of the object to which the hatching is applied.

[0030] The embodiments may be specified by the following items: [Item 1] A catheter (1) comprising: a shaft (2) having a lumen (8); a core wire (12) housed in the lumen (8); and a torque transmission agent (14) filling the space between the inner surface of the shaft (2) and the outer surface of the core wire (12) within the lumen (8), having viscosity or viscoelasticity, and transmitting torque input to the shaft (2) to the core wire (12). [Item 2] The catheter (1) according to Item 1, wherein the torque transmission agent (14) is a gel at 25°C or a liquid having a viscosity greater than 0.89 mPa·S at 25°C. [Item 3] The catheter (1) according to Item 1 or Item 2, wherein the viscosity of the torque transmission agent (14) is 400 mPa·S or more and 5000 mPa·S or less at 25°C. [Item 4] The diameter of the shaft (2) is 3Fr or less, a catheter (1) according to any of Items 1 to 3. [Item 5] When the total length of the shaft (2) is divided into five equal regions, the amount of torque transmission agent (14) filled in the region including the tip of the shaft (2) is greater than the amount of torque transmission agent (14) filled in the region including the proximal end of the shaft (2), a catheter (1) according to any of Items 1 to 4. [Item 6] The lumen (8) is sealed to the outside of the shaft (2), a catheter (1) according to any of Items 1 to 5.

[0031] This disclosure can be used in catheters.

[0032] 1 Catheter, 2 Shaft, 4 Electrode, 6 Connector, 8 Lumen, 10 Conductor, 12 Core Wire, 14 Torque Transmission Agent.

Claims

1. A catheter comprising: a shaft having a lumen; a core wire housed in the lumen; and a torque transmission agent filling the space between the inner surface of the shaft and the outer surface of the core wire within the lumen, having viscosity or viscoelastic properties, and transmitting torque applied to the shaft to the core wire.

2. The catheter according to claim 1, wherein the torque transmission agent is a gel at 25°C or a liquid having a viscosity greater than 0.89 mPa·S at 25°C.

3. The catheter according to claim 1 or 2, wherein the viscosity of the torque transmission agent is 400 mPa·s or more and 5000 mPa·s or less at 25°C.

4. The catheter according to claim 1 or 2, wherein the diameter of the shaft is 3 Fr or less.

5. The catheter according to claim 1 or 2, wherein when the total length of the shaft is divided into five equal regions, the amount of torque transmission agent filled in the region including the tip of the shaft is greater than the amount of torque transmission agent filled in the region including the base of the shaft.

6. The catheter according to claim 1 or 2, wherein the lumen is sealed from the outside of the shaft.

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