catheter

Abstract

To provide a catheter capable of suppressing performance deterioration caused by plastic deformation more effectively, by using a member comprising a flat coil formed by molding spirally a spring steel having a flat cross section.SOLUTION: A catheter 100 has one or more lumens inside, and has, on a shaft part 30, a coil tube 35 formed by cold molding at least a flat spring steel into a coil shape compactly or with a gap of 0.1 mm or less, followed by heat treatment.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In the case of a penetrating catheter that penetrates the embolus together with a guidewire, the tip must be thrust into the embolus and the embolus must be pushed forward. However, if the catheter shaft has a tendency to bend, the force will escape at the bent part when pushing it in, and the force will not be applied straight to the shaft.

[0003] This tendency to bend is mainly due to (1) the fact that the catheter becomes bent when it is inserted into the body. For example, when inserting a catheter into the body, it is first inserted at an angle to the skin and then inserted along the blood vessel, so the tendency to bend can occur due to the curvature that occurs when aligning the catheter with the blood vessel, or when the catheter is gripped too tightly at the proximal end when pushing it in.

[0004] In addition, (2) some catheters can become bent due to packaging. For example, catheters are often packaged in a hard plastic tube that is wound around the body. In such cases, the catheter may become bent overall. This is thought to be particularly likely to occur due to the heat applied during the sterilization process. Also, when removing the catheter from the package during surgery, it may bend at the opening.

[0005] If the catheter becomes bent in this way, when it is pushed into a blood vessel, the force is lost at the bent portion, making it impossible to push the catheter in.

[0006] One proposed catheter that prevents such bending tendency is a medical catheter that has one or more lumens inside and has a metal tubular member in at least a portion thereof, and is characterized in that when the metal tubular member is bent 90 degrees with a curvature radius 50 times its outer diameter and held at that position for one minute and then released, the bending angle of the metal tubular member is within 15 degrees (Patent Document 1).

[0007] This invention provides a medical catheter in which the properties of the metal that forms the inner metal tubular member are controlled by solution heat treatment, quenching, and tempering, and in particular the strength, hardness, and creep properties are controlled by the conditions of solution heat treatment and tempering, resulting in a metal tubular member with specific properties, thereby suppressing performance degradation due to plastic deformation.

[0008] However, the medical catheters described in the above documents require the use of metal materials that meet the conditions for solution heat treatment and tempering, which poses the problem of difficulty in obtaining and processing metal tubular members that meet these conditions. Furthermore, the medical catheters described in the above documents still have insufficient suppression of performance degradation due to plastic deformation. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-271208 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a catheter in which performance degradation due to plastic deformation is more effectively suppressed by using a member made of a flat coil formed by helically shaping spring steel with a flat cross section. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention employs the following means.

[0012] The catheter according to the present invention comprises: It is characterized by having a coil tube in the shaft section, which has one or more lumens inside and is made by cold-forming at least flat spring steel into a coil shape with no gaps or gaps of 0.1 mm or less, and then heat-treating it.

[0013] The catheter of the present invention has a coil tube inserted inside, in which flat spring steel is coiled with no gaps or with gaps of 0.1 mm or less. This prevents the coil from shrinking in the longitudinal direction, improving pushing performance, and also allows the catheter to have a shaft portion with high straightening ability, that is, the ability to return to a straight shape when bent.

[0014] Furthermore, in the catheter according to the present invention, The coil tube may be characterized in that the cross-sectional ratio of the flat coil, where t is the thickness and w is the width, is t:w=1:6 to 1:15, and the thickness t of the flat coil is 1 / 5 or less of the inner diameter Φ1 of the coil tube, and the width w is 1.5 or less of the outer diameter Φ2 of the coil tube.

[0015] By adopting such a configuration, it is possible to provide a coil tube with high straightness return performance.

[0016] Furthermore, in the catheter according to the present invention, The shaft portion may be characterized in that when it is bent 90 degrees with a curvature radius 17.9 times the outer diameter of the coil tube, held in that state for 1 minute, and then released, the bending angle generated in the shaft portion is within 0°. [Effects of the Invention]

[0017] According to the catheter of the present invention, it is possible to provide a catheter in which performance degradation due to plastic deformation is more effectively suppressed. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a side view of a catheter 100 according to an embodiment. [Figure 2] FIG. 2 is an enlarged cross-sectional view taken along line AA of the catheter 100 according to the embodiment. [Figure 3] FIG. 3 is a perspective view showing a coil tube of the catheter 100 according to the embodiment. [Figure 4] FIG. 4 is a schematic diagram showing a method for evaluating the catheter 100 according to the present invention. [Figure 5] FIG. 5 is a schematic diagram showing a method for evaluating the catheter 100 according to the present invention. [Figure 6] FIG. 6 is a table showing test results for examples and comparative examples of the catheter 100 according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Next, an embodiment of a catheter 100 according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a side view of the catheter 100 according to the embodiment. FIG. 2 is an enlarged cross-sectional view taken along line AA of the catheter 100 according to the embodiment. Note that the cross-sectional line has been omitted for clarity. Note that the embodiments and drawings described below exemplify some of the embodiments of the present invention and are not intended to limit the scope of the present invention to these configurations. Appropriate modifications can be made without departing from the spirit of the present invention. Note that, for ease of explanation, in the claims and the specification, the "base end side" and the "tip end side" refer to the proximal side (catheter hub side) of the catheter 100 shown in FIG. 1 as the "base end side" and the distal end side as the "tip end side."

[0020] (First embodiment) As shown in FIG. 1, the catheter 100 according to the first embodiment mainly comprises a tip portion 10, a shaft portion 30, and a catheter hub portion 50.

[0021] As shown in Figure 2, the tip portion 10 can be made of various materials and in various shapes depending on the purpose of use. In this embodiment, a conical tip with a tapered tip is used to penetrate the thrombus. The material used is not particularly limited and may be metal, resin, or the like.

[0022] As shown in FIG. 2, the shaft portion 30 includes, from the inner layer, a resin tube 31, a braided body 33, a coil tube 35, and a resin covering body 37.

[0023] The resin tube 31 is a tube that forms an inner lumen through which a guide wire, a stent, a balloon catheter, or other medical device is inserted, and the braided body 33 and coil tube 35 that are arranged on its outer periphery prevent the guide wire or medical device from getting caught, enhance sliding properties, prevent the braided body 33 from unraveling, and prevent the adhesion of blood clots. The resin is not particularly limited, but it is preferable to use polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), or the like, which have high compatibility with the human body, excellent sliding properties, and shape recovery properties.

[0024] The braided body 33 is made by braiding metal wires or resin wires, and contributes to improving the kink resistance and the pushing function of the shaft in addition to the coil tube 35 described later. Furthermore, it also has the function of preventing the coil tube 35, which is wound tightly in a spiral shape described later, from separating too much when the shaft portion 30 is bent.

[0025] The coil tube 35 is formed from a flat coil of spring steel having a flat cross section, formed into a spiral shape. The spring steel used is not limited to, but may be, SUS301, SUS304, SUS316, or the like. The cross-sectional ratio of the flat plate used in the flat coil, where t is the thickness and w is, is t:w=1:6 to 1:15, more preferably 1:9 to 1:12, as shown in FIG. 3 . Furthermore, the thickness t is preferably 1 / 5 or less of the inner diameter Φ1 of the coil tube 35. For example, if the inner diameter Φ1 is 0.6 mm, t≦0.12 mm is preferred. Furthermore, the width w is preferably 1.5 times or less the outer diameter Φ2. For example, if the outer diameter Φ2 is 0.72 mm, the width w≦1.08 mm is preferred. When forming the spiral, the spiral is formed so that there is no gap between adjacent spirals, or a gap of 0.1 mm or less, as in a so-called tightly wound coil spring. By eliminating or narrowing the gaps in the spiral using flat plate-shaped components, the rigidity of the shaft portion 30 is increased, improving its ability to return to a straight shape after bending. To form the spiral, the spiral is first formed by cold forming. Direct winding around the resin tube 31 is not possible because the tension of the spring steel during winding would deform the resin tube 31. Therefore, the flat coil is first formed into a coil tube. After forming, heat treatment such as quenching and tempering or low-temperature annealing is performed to remove residual stress. As the wire diameter increases relative to the outer diameter of the product, elasticity increases, but repeated recovery (sag) is more likely to occur due to the increased stress. The coil tube 35 of the present invention is made from a flat coil, and therefore is formed with a larger wire diameter relative to the outer diameter. This results in high stress during processing, and when passing through a section with a large curvature, the high stress causes the tube to bend and not return to its original shape. Therefore, heat treatment is carried out to remove stress.

[0026] The resin coating 37 is the outermost layer of the shaft portion 30, and has the function of preventing the coil tube 35 from coming into direct contact with the body, such as blood vessels, and of maintaining the coil in a predetermined position when the shaft portion 30 is bent.

[0027] The catheter hub portion 50 is not particularly limited, and any known catheter hub can be used as appropriate.

[0028] The catheter 100 configured as described above is manufactured as follows. First, as described above, a flat coil is formed into a coil tube, and heat treatment such as quenching and tempering or low-temperature annealing is performed to remove residual stress, thereby obtaining the coil tube 35. After heat treatment, the resin tube 31 around which the braid 33 is wound is inserted from the end into the coil tube 35, and the tube is covered with resin. Then, the distal end is joined to the distal end. When joining the distal end, a radiopaque marker 60 or the like may be attached as desired, as shown in FIG. 2. Meanwhile, the catheter is completed by attaching a catheter hub 50 to the proximal end.

[0029] The shaft portion of the catheter manufactured in this manner can be bent 90 degrees with a radius of curvature 20 times the outer diameter of the coil tube 35, held in this state for 1 minute, and then released, and the bending angle that occurs in the shaft portion can be kept within 0 degrees, resulting in a catheter that is free from bending tendencies and has high straightening ability.

[0030] (Example) Hereinafter, a flat coil having a thickness t of 0.09 mm and a width w of 1.0 mm was used as the coil tube of shaft portion 30, and a coil tube having a coil outer diameter of 0.84 mm was prepared. Example 1 was an unannealed coil tube, Example 2 was a coil tube annealed at 380°C for 20 minutes, and Example 3 was a catheter prepared by inserting a resin tube 31 around which a braided body 33 was wound into coil tube 35 from the end using the coil tube of Example 2 and covering it with resin. As comparative examples, a catheter incorporating a coil made of a 0.03Φ round wire without annealing (Comparative Example 1) and a catheter incorporating a coil made of a flat plate having a thickness t of 0.06 mm, a width w of 5.0 mm, a pitch of approximately 5 mm, and a coil gap of 0.03 mm, which was prepared by laser-cutting an unannealed stainless steel tube (SUS304), were prepared.

[0031] These were bent 90 degrees to radii of curvature of 11.9 times (5 mm radius), 17.9 times (7.5 mm radius), 23.8 times (10 mm radius), 29.8 times (12.5 mm radius), 35.7 times (15 mm radius), 41.7 times (17.5 mm radius), 47.6 times (20 mm radius), and 59.5 times (25 mm radius) the outer diameter of the coil tube, held in this state for one minute, and then released. The bending angle of the shaft was measured. Note that bending a metal tubular member 90 degrees to a radius of curvature of 50 times (50 A) its outer diameter (A) refers to the method shown in Figure 4. In other words, this method involves bending the coil tube 35, with one end fixed, around the circumference of a cylinder with a radius 50 times the outer diameter, so that the extension angle of the unbent portions at both ends of the cylinder is 90 degrees. The bending angle is the angle α at the intersection of the extension lines of the straight parts of the bent member as shown in Figure 5. The measurement results are shown in Figure 6.

[0032] According to Figure 6 showing the measurement results, in the case of the unannealed coil tube (Example 1), a catheter with no bending tendency and high straightness returnability was obtained when the diameter (outer diameter) was 23.8 times or more the diameter (outer diameter) of the coil tube 35. In the case of the annealed coil tube (Example 2) and the catheter using this coil tube (Example 3), a catheter with no bending tendency and high straightness returnability was obtained when the diameter (outer diameter) was 17.9 times or more the diameter (outer diameter) of the coil tube 35. In contrast, in Comparative Example 1, a bending tendency remained at all diameter magnifications, and in Comparative Example 2, kinking (breaking) occurred at diameter magnifications from 11.9 times to 35.7 times, making measurement impossible. This shows that a flat coil is not sufficient, but that if the width (w) is too wide relative to the diameter, kinking will occur in the case of a sharp curvature. [Industrial Applicability]

[0033] As shown in the above-described embodiment, it can be used as an auxiliary tool in surgery using a guide wire or catheter. [Explanation of symbols]

[0034] 10...tip portion, 30...shaft portion, 31...resin tube, 33...braided body, 35...coil tube, 37...resin coating body, 50...catheter hub portion, 60...radiopaque marker, 100...catheter

Claims

1. The shaft portion has a coil tube formed by cold forming at least flat spring steel into a coil shape without any gap or with a gap of 0.1 mm or less, and then heat treating the coil tube, A catheter characterized in that the coil tube is sandwiched between a braided body on the inner layer side and a resin coating on the outer layer side.

2. The coil tube has a cross-sectional ratio of thickness t to width w of the flat coil, t:w=1:6 to 1:15, and the thickness t of the flat coil is equal to the inner diameter Φ of the coil tube. １ and the width w is equal to or less than 1 / 5 of the outer diameter Φ of the coil tube. ２ 2. The catheter according to claim 1, wherein the thickness is 1.5 times or less.

3. 3. The catheter according to claim 1, wherein when the shaft portion is bent 90 degrees with a radius of curvature 17.9 times the outer diameter of the coil tube, held in that state for one minute, and then released, the bending angle generated in the shaft portion is within 0°.

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