Catheter

Abstract

This catheter comprises: a hollow shaft; a first coil that is disposed radially outward from the hollow shaft and is formed by winding a wire; a second coil that is disposed radially outward from the first coil and is formed by winding a wire in the opposite direction to the first coil; and an outer layer that is a resin layer disposed radially outward from the second coil, wherein the outer layer is not attached to the second coil.

Description

Catheter

[0001] The present disclosure relates to a catheter.

[0002] Known medical instruments inserted into a living body lumen include a spiral tube in consideration of rotational followability and flexibility. For example, Patent Documents 1 and 2 disclose a flexible tube of an endoscope provided with a double spiral tube.

[0003] Japanese Patent Application Laid-Open No. 2004-290322, Patent No. 3367415

[0004] In each of the flexible tubes disclosed in Patent Documents 1 and 2, the double spiral tube is covered with an outer layer made of resin or the like. When such an outer skin layer adheres to the spiral tube, it may limit the rotation of the spiral tube when the flexible tube is rotated, thereby reducing the rotational followability of the flexible tube. Such problems are common to all medical instruments such as catheters having a spiral tube such as a coil and an outer layer covering the spiral tube, not limited to the flexible tube of an endoscope.

[0005] An object of the present disclosure is to improve the rotational followability of a catheter.

[0006] The present disclosure has been made to solve at least a part of the above-described problems and can be realized in the following forms.

[0007] According to one aspect of the present disclosure, a catheter is provided. The catheter includes a hollow shaft, a first coil disposed radially outside the hollow shaft and formed by winding wire elements, a second coil disposed radially outside the first coil and formed by winding wire elements in a direction opposite to that of the first coil, and an outer layer which is a resin layer disposed radially outside the second coil, and the outer layer does not adhere to the second coil.

[0008] It is an explanatory diagram illustrating the configuration of the catheter of the first embodiment. It is an explanatory diagram illustrating the cross-sectional configuration of the catheter. It is an explanatory diagram of the heat stretching portion welding method. It is an explanatory diagram showing a resin member. It is an explanatory diagram illustrating the configuration of the catheter of the second embodiment.

[0009] <First Embodiment> Figure 1 is an explanatory diagram illustrating the configuration of the catheter 1 according to the first embodiment. The catheter 1 is a tubular medical device that is inserted into the lumen of living organisms, including blood vessels such as the cardiovascular and cerebrovascular systems, as well as the lymphatic system, biliary system, urinary tract system, airway system, digestive system, secretory glands, and reproductive organs, and used for treatment and examination.

[0010] Figure 1 illustrates mutually orthogonal X, Y, and Z axes. The X-axis corresponds to the axial direction of catheter 1 (the insertion direction of catheter 1), the Y-axis corresponds to the width direction of catheter 1, and the Z-axis corresponds to the height direction of catheter 1. The left side of Figure 1 (+X-axis direction) is called the "tip side" of catheter 1 and its components, and the right side of Figure 1 (-X-axis direction) is called the "proximal end side" of catheter 1 and its components. For catheter 1 and its components, the end located on the tip side and its vicinity are called the "tip," and the end located on the proximal end and its vicinity are called the "proximal end." Of catheter 1, the tip side is the part inserted into the body, and the proximal end is the part manipulated by a surgeon such as a physician. These points are also common in Figure 1 and subsequent figures.

[0011] In Figure 1, the axis passing through the center of the catheter 1 is represented by axis O (dotted line). The center of the catheter 1 refers to the center of each cross-section of the catheter 1 when it is cut in the YZ plane. In the example in Figure 1, the axis passing through the center of the catheter 1 coincides with the axis passing through the centers of each component of the catheter 1. However, the axis passing through the center of the catheter 1 may differ from the axis passing through the centers of each component of the catheter 1.

[0012] Catheter 1 comprises seven tubular members: a hollow shaft 10, an inner coil 20, a middle layer 30, a first coil 40, a second coil 50, a blade 60, and an outer layer 70. In Figure 1, a catheter 1 is shown in which the number of tubular members decreases in stages towards the tip, in order to make each of the seven tubular members easier to see. The original catheter 1 has a seven-tube structure throughout the entire length in the axial direction, the X-axis direction. The number of tubular members may decrease in stages towards the tip.

[0013] The hollow shaft 10 is a tubular member extending along the X-axis. In this embodiment, the axis passing through the center of the hollow shaft 10 coincides with axis O. As the material forming the hollow shaft 10, for example, resin materials such as polyamide resin, polyolefin resin, polyester resin, polyurethane resin, silicone resin, and fluororesin can be used. In this embodiment, the material forming the hollow shaft 10 is PTFE (polytetrafluoroethylene).

[0014] The inner coil 20 is a substantially tubular member extending along the X-axis. The inner coil 20 is positioned radially outward of the hollow shaft 10 and covers the hollow shaft 10. Radially outward means the side in the direction away from the axis O in the YZ plane. The inner coil 20 is formed by winding wires. As the material forming the wires, for example, stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, radiotransparent materials such as piano wire, and radiopaque materials such as platinum, gold, and tungsten can be used. In this embodiment, the material forming the wires of the inner coil 20 is stainless steel. The same applies to the wires used to form the first coil 40 and the second coil 50, which will be described later.

[0015] In this embodiment, the inner coil 20 is a single-strand coil formed by winding a single strand. The inner coil 20 may also be a multi-strand coil formed by winding multiple strands of multiple strands, a single stranded wire coil formed by winding a single stranded wire formed by twisting multiple strands together, or a multi-strand stranded coil formed by using multiple strands formed by twisting multiple strands together and winding each stranded wire in multiple directions. The inner coil 20 may be formed by arbitrarily combining a single-strand coil, a multi-strand coil, a single stranded wire coil, and a multi-strand stranded wire coil. The same applies to the first coil 40 and the second coil 50, which will be described later.

[0016] The intermediate layer 30, which is a resin layer, is a tubular member extending along the X-axis direction. The intermediate layer 30 is positioned radially outside the inner coil 20 and covers the inner coil 20. As the resin material forming the intermediate layer 30, resin materials such as polyamide resin, polyamide elastomer resin, polyester resin, and polyurethane resin can be used. In this embodiment, the material forming the intermediate layer 30 is PB35, a polyamide elastomer resin.

[0017] The first coil 40 is a substantially tubular member extending along the X-axis direction. The first coil 40 is positioned radially outward of the intermediate layer 30 and covers the intermediate layer 30. The first coil 40 can also be considered to be positioned radially outward of the hollow shaft 10. The first coil 40 is formed by winding strands of wire. In this embodiment, the first coil 40 is a single-strand coil formed by winding a single strand of wire. The intermediate layer 30 is attached to the first coil 40. The state in which the intermediate layer 30 is attached to the first coil 40 is at least one of the following states: the intermediate layer 30 is impregnated between the strands forming the first coil 40, or the intermediate layer 30 is adhered to the outer circumferential surface of the first coil 40.

[0018] The second coil 50 is a substantially tubular member extending along the X-axis direction. The second coil 50 is positioned radially outside the first coil 40 and covers the first coil 40. The second coil 50 is formed by winding a wire in the opposite direction to that of the first coil 40. In this embodiment, the second coil 50 is a single-strand coil formed by winding a single wire.

[0019] The blade 60 is a substantially tubular member extending along the X-axis direction. The blade 60 is positioned radially outside the second coil 50 and covers the second coil 50. The blade 60 is formed by braiding strands of wire. A portion of the blade 60 is embedded in the outer layer 70, which will be described later. The material forming the blade 60 can be the same material as that used for the inner coil 20 described above. In this embodiment, the material forming the blade 60 is stainless steel.

[0020] The outer layer 70, which is a resin layer, is a tubular member extending along the X-axis. The outer layer 70 is positioned radially outside the blade 60 and covers the blade 60. The outer layer 70 can also be considered to be positioned radially outside the second coil 50 and radially outside the blade 60. The outer layer 70 includes a first outer layer 72 and a second outer layer 74. The first outer layer 72 is the portion of the outer layer 70 that is inside the second outer layer 74 and directly covers the blade 60. The second outer layer 74 is the portion of the outer layer 70 that is outside the first outer layer 72 and indirectly covers the blade 60 via the first outer layer 72. Any resin material can be used as the material forming the first outer layer 72, as long as its melting point is lower than that of the material forming the second outer layer 74. In this embodiment, the material forming the first outer layer 72 is PB35, a polyamide elastomer resin. In this embodiment, the material forming the second outer layer 74 is polyamide resin L1940.

[0021] Figure 2 is an explanatory diagram illustrating the cross-sectional structure of catheter 1. Figure 2 shows a cross-section of catheter 1 when cut in the XZ plane. In Figure 2, in order to make the state of the first coil 40, second coil 50, blade 60, and outer layer 70 easier to see, the hollow shaft 10, inner coil 20, and middle layer 30, which are originally located inside the first coil 40, are omitted from the illustration.

[0022] As shown in Figure 2, a portion of the outer surface of the first coil 40 is in contact with a portion of the inner surface of the second coil 50. A portion of the outer surface of the second coil 50 is in contact with a portion of the inner surface of the blade 60. As described above, a portion of the blade 60 is embedded in the outer layer 70.

[0023] As shown in Figure 2, the outer layer 70 is not attached to the second coil 50. More specifically, the first outer layer 72 is not attached to the second coil 50. The state in which the first outer layer 72 is not attached to the second coil 50 means that the first outer layer 72 is not impregnated between the strands forming the second coil 50, and the first outer layer 72 is not adhered to the outer surface of the second coil 50. Therefore, since the second coil 50 is not fixed to the outer layer 70, the rotation of the second coil 50 is not restricted by the outer layer 70 when the catheter 1 is rotated. Of course, the rotation of the first coil 40 is also not restricted by the outer layer 70.

[0024] Figure 3 is an explanatory diagram of the heat-stretched partial welding method. Figure 4 is an explanatory diagram showing the resin member 70P. The composite CP shown in Figure 3 is a six-tube structure member comprising a hollow shaft 10, an inner coil 20, a middle layer 30, a first coil 40, a second coil 50, and a blade 60. In other words, the composite CP is the member obtained by removing the outer layer 70 from the catheter 1. The resin member 70P shown in Figures 3 and 4 is a tubular member corresponding to the outer layer 70 before heat stretching. Figure 4 shows the cross-section of the resin member 70P when cut in the YZ plane. As shown in Figure 4, the resin member 70P includes a first resin layer 72P which is the basis of the first outer layer 72, and a second resin layer 74P which is the basis of the second outer layer 74.

[0025] Using Figure 3, the manufacturing process of catheter 1, specifically the step of covering the composite CP with the outer layer 70, will be explained. First, the manufacturer places the prepared composite CP inside the resin member 70P shown by the solid line. Next, the manufacturer heats and stretches the resin member 70P as shown by the dashed line, and then welds the resin member 70P to the outer surface of the composite CP. During this heating and stretching, the manufacturer adjusts the heating temperature so that the entire resin member 70P is stretched, but the second resin layer 74P does not melt, and only the first resin layer 72P melts. The resin member 70P that has solidified on the outer surface of the composite CP after heating and stretching corresponds to the outer layer 70. Similarly, the first resin layer 72P and the second resin layer 74P that have solidified on the outer surface of the composite CP after heating and stretching correspond to the first outer layer 72 and the second outer layer 74, respectively. Since the amount of resin that permeates the blade 60 during heat stretching varies depending on the thickness of the first resin layer 72P of the resin member 70P, the manufacturer pre-adjusts the thickness of the first resin layer 72P so that the outer layer 70 (first outer layer 72) adheres to the blade 60 but does not adhere to the second coil 50.

[0026] As described above, the catheter 1 of the first embodiment is equipped with a first coil 40 and a second coil 50, which improves the rotational responsiveness and flexibility of the catheter 1. In the catheter 1 of the first embodiment, the winding direction of the first coil 40 and the winding direction of the second coil 50 are different, making it easier to bend the catheter 1 in any direction. In the catheter 1 of the first embodiment, the outer layer 70 is not attached to the second coil 50. Therefore, when the catheter 1 is rotated, the rotation of the first coil 40 and the second coil 50 is not restricted by the outer layer 70, thus improving the rotational responsiveness of the catheter 1. Accordingly, the catheter 1 of the first embodiment provides a catheter 1 that is highly flexible, easy to bend in any desired direction, and has improved rotational responsiveness. Rotational responsiveness refers to the ability of the tip of the catheter 1 to rotate in accordance with the rotation of the proximal end when the proximal end of the catheter 1 is rotated.

[0027] In the catheter 1 of the first embodiment, a portion of the outer surface of the first coil 40 is in contact with a portion of the inner surface of the second coil 50, and a portion of the outer surface of the second coil 50 is in contact with a portion of the inner surface of the blade 60, thereby further improving the rotational tracking ability of the catheter 1.

[0028] <Second Embodiment> Figure 5 is an explanatory diagram illustrating the configuration of the catheter 1a of the second embodiment. The catheter 1a of the second embodiment is the same as the catheter 1 of the first embodiment shown in Figure 1, except that it is equipped with a blade 20a instead of an inner coil 20 and a third coil 60a instead of a blade 60.

[0029] The blade 20a is a substantially tubular member extending along the X-axis direction. The blade 20a is positioned radially outward of the hollow shaft 10 and covers the hollow shaft 10. The blade 20a is formed by braiding strands of wire, similar to the blade 60 of the first embodiment. The material forming the blade 20a is stainless steel, similar to the blade 60 of the first embodiment.

[0030] The third coil 60a is a substantially tubular member extending along the X-axis direction. The third coil 60a is positioned radially outside the second coil 50 and covers the second coil 50. The third coil 60a is formed by winding strands of wire in the same direction as the first coil 40. In this embodiment, the third coil 60a is a single-strand coil formed by winding a single strand of wire. The third coil 60a may be a multi-strand coil, a single-strand stranded coil, or a multi-strand stranded coil, similar to the first coil 40 and the second coil 50. In the catheter 1a of the second embodiment, the outer layer 70 is positioned radially outside the third coil 60a and covers the third coil 60a. In the catheter 1a of the second embodiment, the outer layer 70 is not attached to the second coil 50, but the outer layer 70 is attached to the third coil 60a.

[0031] As described above, in the catheter 1a of the second embodiment, similar to the catheter 1 of the first embodiment, the outer layer 70 is not attached to the second coil 50, so the rotation of the first coil 40 and the second coil 50 is not restricted by the outer layer 70, thus improving rotational tracking performance. Furthermore, the catheter 1a of the second embodiment is equipped with a third coil 60a as a coil that contributes to rotational tracking performance, thus further improving rotational tracking performance.

[0032] <Modifications of this Embodiment> This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit thereof. For example, the following modifications are also possible.

[0033] In the first embodiment described above, a portion of the outer circumferential surface of the first coil 40 was in contact with a portion of the inner circumferential surface of the second coil 50, and a portion of the outer circumferential surface of the second coil 50 was in contact with a portion of the inner circumferential surface of the blade 60. A portion of the outer circumferential surface of the first coil 40 does not have to be in contact with a portion of the inner circumferential surface of the second coil 50. A portion of the outer circumferential surface of the second coil 50 does not have to be in contact with a portion of the inner circumferential surface of the blade 60.

[0034] The second embodiment described above may further include a blade positioned radially outward of the third coil 60a and radially inward of the outer layer 70.

[0035] In the second embodiment described above, a portion of the outer circumferential surface of the second coil 50 may be in contact with a portion of the inner circumferential surface of the third coil 60a.

[0036] In the first embodiment described above, the pitch of at least one of the first coil 40, the second coil 50, and the blade 60 may be larger towards the tip of the catheter 1. In this case, the catheter 1 can be made more flexible towards the tip and more rigid towards the proximal end. That is, the catheter 1 can be made easier to insert into a biological lumen. Similarly in the second embodiment described above, the pitch of at least one of the first coil 40, the second coil 50, and the third coil 60a may be larger towards the tip of the catheter 1a.

[0037] This embodiment has been described above based on embodiments and modifications. The embodiments described above are for the purpose of facilitating understanding of this embodiment and do not limit it. This embodiment can be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this embodiment. Technical features that are not described as essential in this specification may be deleted as appropriate.

Claims

1. A catheter (1, 1a) comprising: a hollow shaft (10); a first coil (40) formed by winding wires and positioned radially outside the hollow shaft (10); a second coil (50) formed by winding wires in the opposite direction to the first coil (40) and positioned radially outside the first coil (40); and an outer layer (70) which is a resin layer positioned radially outside the second coil (50), wherein the outer layer (70) is not attached to the second coil (50).

2. A catheter (1, 1a) according to claim 1, wherein a portion of the outer surface of the first coil (40) is in contact with a portion of the inner surface of the second coil (50).

3. A catheter (1) according to claim 1 or claim 2, further comprising a blade (60) formed by braiding strands and arranged radially outside the second coil (50), wherein the outer layer (70) is arranged radially outside the blade (60), and a portion of the outer circumferential surface of the second coil (50) is in contact with a portion of the inner circumferential surface of the blade (60).

4. A catheter (1a) according to claim 1 or claim 2, further comprising a third coil (60a) arranged radially outside the second coil (50) and formed by winding strands in the same direction as the first coil (40), wherein the outer layer (70) is arranged radially outside the third coil (60a).

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