Medical device

Abstract

To provide a medical device for preventing deformation of an auger in a medical device for approaching a hardened lesioned part such as calcification.SOLUTION: A disclosed medical device (a catheter 1) includes a first coil body 21 wound in a first direction and a second coil body 22 wound outside the first coil body in a second direction different from the first direction. The second coil body 22 is constituted as an auger 3 in at least its distal end part, and a distal end part 3a of the auger 3 is joined to the first coil boy 21.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to medical devices. [Background technology]

[0002] Conventionally, there is known a technique for a catheter equipped with an auger for entering a lesion in surgery for narrowed or blocked areas of blood vessels, digestive organs, etc. For example, Patent Document 1 proposes an invention of a catheter provided with an auger and a protective layer for the auger at the tip of a rotatable shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2019-146968 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the invention of Patent Document 1, the auger is made of a resin such as nylon or polyester, so there was a problem that the auger was easily crushed when entering a lesion hardened by limestone or the like, reducing the effectiveness of the auger.

[0005] When the auger is made of a material with a high elasticity such as metal, a high propulsive force can be obtained. However, when the tip of the auger is advanced into the lesion, resistance is applied from the tip of the auger, and torque transmission from the base end side of the catheter becomes dominant, and a force opens the auger toward the outer periphery, causing the auger to deform and float. Even if a protective layer is provided on the auger, the deformation cannot be suppressed, and there is also a risk that the auger will become unable to remove the catheter due to deformation, or that the auger will break off and remain in the lesion.

[0006] Therefore, an object of the present disclosure is to provide a medical device that can prevent deformation of the auger. [Means for solving the problem]

[0007] In order to solve the above problems, the medical device disclosed herein comprises a first coil body wound in a first direction and a second coil body wound around the outside of the first coil body in a second direction different from the first direction, the second coil body being configured as an auger at least at its tip, and the tip of the auger being joined to the first coil body. Effect of the Invention

[0008] According to the catheter of the present disclosure, the first coil body and the second coil body are wound in mutually different directions, and at least the tip of the second coil body is configured as an auger, and the tip of the auger is joined to the first coil body. Therefore, when the auger advances toward the lesion, the torque of the first coil body is transmitted to the auger, while when the auger retreats from the lesion, the torque from the second coil body is transmitted to the auger, so that a tightening force acts on the inner periphery of the auger, and deformation of the auger can be prevented. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an overall view of a catheter according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a first coil body (a) and a second coil body (b). [Diagram 3] FIG. 13(a) is a schematic diagram showing the state in which the catheter is advanced toward the lesion, and FIG. 13(b) is an action diagram showing the action of the first coil body on the auger. [Figure 4] FIG. 13(a) is a schematic diagram showing the state in which the catheter is retracted from the lesion, and FIG. 13(b) is an action diagram showing the action of the third coil body on the auger. [Diagram 5] FIG. 11 is an overall view of a catheter according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view of the vicinity of the tip of a catheter of embodiment 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the medical device of the present disclosure embodied as a catheter will be described with reference to the drawings. In this disclosure, the catheter is a penetration catheter. In the following description, the left side of Fig. 1 is the tip side (distal side) inserted into the body, and the right side is the rear end side (hand side, base end side) operated by a technician such as a doctor. In addition, the direction from the base end to the tip is the forward direction, and the direction from the tip to the base end is the backward direction. EXAMPLES

[0011] 1 and 2, the catheter 1 of the first embodiment includes an inner tube 4, a distal tip 6 provided at the distal end of the inner tube 4, an outer tube 5 provided coaxially with the inner tube 4, a connector 7 which is an operation unit operated by an operator such as a doctor, and a coil 2 (first and second coil bodies 21, 22) which transmits torque applied to the connector 7. The catheter 1 is used, for example, for treating narrowed or blocked areas of blood vessels (coronary arteries) of the heart.

[0012] The outer tube 5 and the inner tube 4 are cylindrical members formed from resin and have flexibility. The inner tube 4 is inserted into the outer tube 5, and the base end 4b of the inner tube 4 is connected to the base end 5b of the outer tube 5. A space is formed inside the inner tube 4 for inserting the guide wire 8. The outer tube 4 extends to just before the joint 22c between the auger 3 and the third coil body 23, and the tip end 4a and base end 4b are joined to the coil 2. The resin used for the outer tube 5 and the inner tube 4 can be polyamide, polyamide elastomer, polyolefin, polyester, polyester elastomer, or the like.

[0013] Here, variations in the state in which the coil 2 is joined to the inner tube 4 and the outer tube 5 are shown in (1) to (3). (1) The coil 2 and the inner tube 4 are joined at two or more points including both ends (tip ends 2a, 4a, base ends 2b, 4b), and the coil 2 and the outer tube 5 are joined at two or more points including both ends (tip ends 2a, 5a, base ends 2b, 5b). (2) An outer tube 5 is crimped onto the outer periphery of the coil 2. (3) The outer tube 5 penetrates into the inside of the coil 2 through the gap in the coil 2 , and the penetrated outer tube 5 is crimped to the inner tube 4 .

[0014] The tip tip 6 is made of a resin (polyurethane, polyurethane elastomer, polyamide, polyamide elastomer, etc.). The tip tip 6 may be made of a resin that is softer than the resin that forms the tip portion 4a of the inner tube 4. The tip tip 6 is a tapered tubular member whose outer diameter gradually decreases toward the tip. The tip tip 6 is provided coaxially with the inner tube 4.

[0015] The wire of the coil 2 is a single wire made of one material, or a twisted wire made of multiple materials twisted together. The material of the single wire may be metal, resin, or a composite material of metal and resin. The metal may be stainless steel or the like. The resin is preferably a hard resin such as PEEK, PET, or polyimide. The composite material may be a monofilament having a metal wire as a core and a resin layer on the outside. The material of the twisted wire may be metal such as stainless steel, platinum (Pt), platinum iridium (Pt-Ir), or nickel titanium (Ni-Ti). The single wire may have any cross-sectional shape such as a round wire, a triangular wire, a trapezoidal wire, or a rectangular wire.

[0016] The coil 2 includes a first coil body 21 and a second coil body 22. The first coil body 21 is wound around the inner tube 4 in a first direction. The second coil body 22 is wound around the outside of the first coil body 21 in a second direction different from the first direction, and is configured as an auger 3 in a predetermined region r2 including at least its own tip portion 22a. The second coil body 22 includes an auger 3 and a third coil body 23. A base end portion 3b of the auger 3 and a tip portion 23a of the third coil body 23 are joined. The tip portion 3a of the auger 3 is joined to the tip portion 21a of the first coil body 21.

[0017] The auger 3 is configured with a one to four thread right-hand or left-hand screw. When the auger 3 is a right-hand screw, the winding direction of the right-hand screw is a first direction, and the winding direction of the left-hand screw is a second direction. When the auger 3 is a right-hand screw, the auger 3 advances within the lesion D by rotating to the right (forward rotation), and retreats within the lesion D by rotating to the left (reverse rotation). The auger 3 is wound in the same direction as the third coil body 23 and at a different pitch from the third coil body 23. The auger 3 is provided so that the maximum diameter of the circumscribed circle is larger than that of the third coil body 23. That is, the maximum value of the outer diameter of the auger 3 is larger than the maximum value of the third coil body 23. The auger 3 can gradually reduce the diameter of the circumscribed circle toward the tip 3a.

[0018] The first coil body 21 is a densely wound multi-strand coil. "Densely wound" refers to a winding state in which the strands are in close contact or close to each other in the axial direction, and when rotated in the tightening direction, interference occurs between the strands. Here, when the catheter 1 advances toward the lesion D, the first coil body 21 wound in the first direction is deformed in the tightening direction by the forward rotation. At this time, since the first coil body 21 is densely wound, there is no or very little gap between the strands, and the strands of the multi-strand coil interfere with each other more strongly, thereby improving the torque transmission characteristics in the forward direction. The tip portion 21a of the first coil body 21 is joined to the tip portion 4a of the inner tube 4. Alternatively, the tip portion 21a of the first coil body 21 can be joined to the tip tip 6.

[0019] The third coil body 23 is a multi-strand coil wound in a sparse manner. "Sparse winding" refers to a winding state in which the wires are wound with gaps in the axial direction, and no interference occurs between the wires even when rotated in the tightening direction. Because the third coil body 23 is a multi-strand coil, the torque transmission characteristics in the backward direction can be improved. In the backward direction, the third coil body 23 is rotated in the tightening direction, which causes interference with the first coil body 21, thereby improving the torque transmission characteristics.

[0020] Here, by densely winding the first coil body 21, it is possible to further enhance the effect of preventing the auger 3 from being trapped and peeling off when the catheter 1 is rotated in the forward direction. When the first coil body 21 is densely wound, interference occurs between the strands of the first coil body 21, which increases the torque of the first coil body 21 when moving forward, and the torque is transmitted from the tip side of the catheter 1. As a result, a force acts to tighten the auger 3 toward the inner circumference. As a result, the above-mentioned effect is obtained.

[0021] Next, a procedure for surgery using the catheter 1 configured as described above will be described. First, the guidewire 8 is inserted into the hardened lesion D of the blood vessel. Next, the catheter 1 is inserted toward the lesion D along the inserted guidewire 8.

[0022] Here, as shown in Figure 3, when the catheter 1 is rotated in the direction of advancing toward the lesion D, resistance is applied to the tip 3a side of the auger 3, and torque is applied from the base end 3b side of the auger 3. Meanwhile, due to the interference effect between the strands of the first coil body 21, the torque of the entire first coil body 4 increases, and the torque from the tip side of the catheter 1 is predominantly transmitted to the auger 3 against the torque from the base end side. As a result, a force f1 (Figure 3(b)) that tightens toward the inner circumference is applied to the auger 3, and the auger 3 behaves as if it is gripping the first coil body 21.

[0023] After the catheter 1 is inserted toward the lesion D, the catheter 1 is removed. Then, a balloon (not shown) is inflated to expand the blood vessel from the inside. Finally, a stent (not shown) is delivered, expanded, and placed in place. Through the above surgery, a blood passage is established, and blood flow can be restored.

[0024] Here, as shown in Figure 4, when the catheter 1 is rotated in the direction of retreating from the lesion D, the first coil body 21 is deformed to open outward due to twisting. In contrast, the third coil body 23 is deformed to tighten inward, causing the deformations of the first coil body 21 and the third coil body 23 to interfere with each other. As a result, the apparent torsional rigidity increases, and high torque is generated. For this reason, the torque from the base end side of the catheter 1 is predominantly transmitted to the auger 3. As a result, a force f2 (Figure 4(b)) that tightens inward is applied to the auger 3, and the auger 3 behaves as if it is gripping the first coil body 21.

[0025] According to the catheter 1 of Example 1, a force that tightens the auger 3 toward the inner circumference is always applied to the auger 3 regardless of the direction of advancement, which has the effect of suppressing the force that opens the auger 3 toward the outer circumference and preventing deformation of the auger 3. EXAMPLES

[0026] 5 and 6, in the catheter 1 of Example 2, the wires of the first coil body 4 are separated from each other at least in a portion on the tip side of the rear end (base end portion 3b) of the auger 3. In addition, the gaps s formed by the separation of the wires of the first coil body 21 are filled with resin 9. Specifically, the tip portion of the catheter 1 (region r1 of the first coil body 21 overlapping with the auger 3) is loosely wound, and the spaces between the coils are filled with resin 9. Note that it is sufficient for the resin 9 to fill the gaps s of the first coil body 21, and there is no need to provide the resin 9 on the outside 21c or inside 21d of the first coil 21.

[0027] When the catheter 1 of Example 2 is rotated in the direction of advancing toward the lesion D, the interference effect between the wires of the first coil body 21 is transmitted via the resin 9, and similarly to Example 1, the torque from the tip side of the catheter 1 is predominantly transmitted to the auger 3 (see FIG. 3(b)). The case where the catheter 1 of Example 2 is rotated in the direction of retreating from the lesion D is omitted because it is similar to Example 1.

[0028] According to the catheter 1 of Example 2, the first coil body 21 is loosely wound at the tip portion of the catheter 1, i.e., in the region r1, and therefore it is possible to improve the flexibility of the tip portion of the catheter 1. Meanwhile, since the gaps s of the first coil body 21 are filled with resin 9, it is possible to reliably transmit interference between the wires via the resin 9, and it is possible to improve the torque transmission characteristics in the forward direction.

[0029] The present disclosure is not limited to the above-described embodiments, and may be implemented by appropriately modifying the shape and configuration of each part as described below in (1) to (5) without departing from the spirit of the present disclosure. (1) The catheter 1 may be a medical device other than a penetration catheter. For example, the catheter 1 may be a medical device such as a dilator used for purposes such as expanding or facilitating expansion of a calcification by cutting a surface into the calcification, or may be any other long medical device. (2) The joining method may be thermal welding, or an adhesive such as an epoxy adhesive or a cyanoacrylate adhesive may be applied. (3) The auger 3 may be partially or entirely covered with a polyamide elastomer, polyurethane elastomer, silicone, or the like, including the joint with the first coil body 21. (4) The first coil body 21 may be a single-strand coil, and the third coil body 23 may be a single-strand coil. (5) The second coil body 22 may be formed only by the auger 3. In other words, the base end portion 22b of the second coil body 22 may coincide with the base end portion 3b of the auger 3. [Explanation of symbols]

[0030] 1 Catheter 2 Coil 3. Ogre 4. Inner tube 5 Outer tube 6 Tip 7 Connectors 8 Guidewire 9. Resin 21 First coil body 22 Second coil body 23 Third coil body D. Lesion

Claims

1. A medical device comprising a first coil body wound in a first direction and a second coil body wound outside the first coil body in a second direction different from the first direction, wherein the second coil body is configured as an auger at least at its tip, and the tip of the auger is joined to the first coil body.

2. The medical device according to claim 1, wherein the strands of the first coil body are separated from each other at least in a part on the tip side of the rear end of the auger.

3. The medical device according to claim 2, wherein the gap formed by the separation of the strands of the first coil body is filled with resin.

4. The medical device according to any one of claims 1 to 3, wherein the second coil body includes the auger and a multi-strand coil joined to the base end portion of the auger.

5. The medical device according to any one of claims 1 to 3, wherein the second coil body is a sparse winding.

6. The medical device according to any one of claims 1 to 3, wherein the first coil body is a tight winding at least on the rear end side of the rear end of the auger.

7. The medical device according to any one of claims 1 to 3, wherein the first coil body is a multi-strand coil.

8. The medical device according to any one of claims 1 to 3, wherein the maximum value of the outer diameter of the auger is larger than the maximum value of the outer diameter of the part on the rear end side of the base end portion of the auger in the second coil body.

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