JP2004283433A - Medical guide wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a medical guide wire wherein the flexibility of a tip is not damaged when being curved by a small curvature in the medical guide wire consisting of a core wire and a coil spring. <P>SOLUTION: In the medical guide wire consisting of the core wire and the coil spring coating the outer periphery of the core wire, the pitch of at least a part of the coil spring is larger than that of the other parts, and preferably, the pitch of the coil spring at the tip of the guide wire is larger than the pitch of a coil spring at the other parts. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１６】
【発明の効果】
以上説明したように、本発明によって、本体部の剛性が高く、かつ、小さな曲率で曲げても先端柔軟性を損なわないガイドワイヤーを得ることができる。
【図面の簡単な説明】
【図１】本発明の医療用ガイドワイヤーの一実施例の断面図。
【図２】従来の医療用ガイドワイヤーの断面図。
【図３】試験方法１の作業台の側面から見た概略図。
【図４】試験方法２の作業台の上面から見た概略図。
【符号の説明】
１．ガイドワイヤー
２．芯線
３．コイルスプリング
４．先端固定部
５．後端固定部
６．芯線先端部
７．テーパー部
８．細径部
９．ポリエチレン製チューブ
１０．１ｇ分銅[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a medical guidewire.
[0002]
[Prior art]
Various catheters are used for injecting a drug solution into the body or discharging unnecessary substances out of the body.In these catheters, both ends or one end are formed in a pigtail shape, and the fixation during indwelling in the body is performed. Many have been improved. A guide wire is generally used when introducing these catheters into the body. This guide wire requires an appropriate rigidity in its main body in order to temporarily straighten the catheter formed in a pigtail shape.
In recent years, a metal having a superelastic property, for example, a nickel titanium alloy or the like has been widely used for a core wire of a guide wire. The greatest advantage of a guide wire using a super-elastic metal core wire is that it is difficult to bend, and that it is used as a guide when percutaneously inserting a catheter into the body. And can be relatively easily inserted into a large curved lumen.
[0003]
However, these metals having superelastic properties have a disadvantage that they have lower bending elasticity than stainless steel conventionally used as a core wire of a guide wire, and do not have appropriate rigidity as a guide wire. That is, when one end of the catheter used in combination has a pigtail shape, the pigtail cannot be sufficiently linearized, and it becomes difficult to insert the catheter.
In order to increase the rigidity of the guide wire, it is easy to increase the outer diameter of the core wire used. When the outer diameter of the guide wire is constant, creating the guide wire only from the core wire is the most effective way to increase the rigidity of the guide wire, but in this case, the contact area between the guide wire and the catheter or body tissue is large. Therefore, the insertion resistance of the guide wire itself or the catheter inserted along the guide wire becomes extremely large, and is not practical as a guide wire. Therefore, some measures are required to reduce the insertion resistance. One of the measures is to cover the core wire with a coil spring. By covering with a coil spring, the contact area with the catheter or body tissue is reduced, and the insertability is improved. Normally, a guide wire covered with a coil spring has a thin wire built in as a safety wire in addition to the core wire inside the coil spring, and the rear end of the guide wire is fixed by welding or the like to the core wire, the safety wire and the coil spring, At the tip of the guide wire, a safety wire and a coil spring are fixed by welding or the like. A core wire does not exist inside the distal end portion of the guide wire, and there is a portion where only the safety wire exists, and the distal end portion of the guide wire forms a flexible portion of the guide wire. The tip of the core wire is tapered toward the tip so that the flexibility gradually increases.
[0004]
In order to improve the rigidity of the type of guide wire whose core wire is covered with a coil spring, the safety wire is omitted, a small diameter portion is created at the tip of the tapered portion at the tip of the core wire, and both ends of the core wire are fixed to the coil spring. It is conceivable that this method is the most rigid in a guide wire of the type covered with a coil spring.
However, in this structure, when the guide wire is bent at a small curvature, since the radius of curvature of the core wire and the radius of curvature of the coil spring are different, the abnormality of the coil spring due to the relative position of the core wire and the coil spring being shifted, especially There have been problems such as a loss of flexibility of the distal end flexible portion and a positional shift between coils.
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a medical guidewire which has high rigidity and which does not cause an abnormality in the flexible distal end portion even when bent at a small radius of curvature, with the object of solving the above problems.
[0006]
[Means for Solving the Problems]
That is, the present invention
(1) A medical guidewire comprising a core wire and a coil spring covering the outer periphery of the core wire, wherein a pitch of at least a part of the coil spring is larger than other parts,
(2) The medical guidewire according to (1), wherein the pitch of the coil spring at the distal end of the guide wire is larger than the pitch of the coil spring at the other portion.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to examples. FIG. 1 schematically shows a medical guidewire (1) according to one embodiment of the present invention. The medical guide wire (1) includes a core wire (2), a coil spring (3), a front end fixing portion (4), and a rear end fixing portion (5). The core wire (2) is made of a stainless steel wire having a total length of 200 to 5000 mm and an outer diameter of 0.1 to 1.0 mm or a metal exhibiting superelastic properties, and its tip portion (6) gradually has flexibility toward the tip. It is preferable that a tapered portion (7) and a small-diameter portion (8) are formed so as to increase. In order to make the guide wire rigid, the outer diameter of the core wire (2) is preferably as large as possible, and is preferably the same as the inner diameter of the coil spring (3).
[0008]
The coil spring (3) is made of a stainless steel wire having a diameter of 0.05 to 0.3 mm or a metal exhibiting superelasticity. The core wire (2) is formed so that the entire guide wire has a diameter of 0.2 to 2.0 mm. Coated. The core wire (2) and the coil spring (3) are fixed at both ends by a method such as welding, brazing, caulking, etc., and the front end fixing part (4) and the rear end fixing part (5) are both hemispherical. It is attached. The coil spring (3) may be coated with a fluororesin or the like in order to improve the slipperiness with a catheter, a body tissue or the like. The main body of the coil spring (3) is densely wound, that is, wound in a state in which the interval between the coils is close to 0, and the distal end of the coil spring (3) extends from 10 to 100 mm from the distal end of the guide wire (1). It is preferable that the distance between the coils is 0.0005 to 0.02 mm. That is, the pitch of the tip of the coil spring (3) is larger than that of the main body.
[0009]
When the guide wire (1) is bent with a relatively small curvature, a relative position shift occurs due to the difference in the radius of curvature between the core wire (2) and the coil spring (3), similarly to the conventional guide wire. However, when the guide wire (1) is in a straight state, the tip of the coil spring (3) is wound with a larger pitch than the main body, that is, since the interval between the coils is large, the core wire when bent at a small curvature. The gap between the relative position of (2) and the coil spring (3) can be absorbed by this gap, and the flexibility of the tip of the guide wire (1) is impaired, and the position of the coil spring (3) is shifted. I can't.
[0010]
【Example】
(Example 1)
Example 1 was created based on FIG. The guide wire (1) of Example 1 has a total length of 1500 mm and an outer diameter of 0.97 mm. The core wire (2) has an outer diameter of 0.6 mm, and its distal end portion is reduced in diameter toward the distal end. The length of the tapered portion (7) of the core wire (2) is 100 mm, the diameter of the small diameter portion (8) is 0.17 mm, and the length is 20 mm. The coil spring (3) has an outer diameter of 0.13 mm, a section of 50 mm from the tip of the guide wire (1) has a spacing of 0.005 mm between the coils, and the other portions are tightly wound.
[0011]
(Comparative Example 1)
The dimensions of the guide wire (1), such as the total length and the outer diameter, were the same as those in Example 1, and the coil spring (3) was tightly wound over the entire length of the guide wire (1) to prepare a guide wire having a constant pitch.
[0012]
The flexibility of the distal flexible portion of the guide wires of Example 1 and Comparative Example 1 was measured by the following two test methods.
(Test method 1)
A polyethylene tube (9) having an inner diameter of 2.8 mm was fixed on a workbench in a straight state, and the guide wires of Example 1 and Comparative Example 1 were inserted into the polyethylene tube (9). A guide wire is fixed at a point protruding 30 mm from the tip of the tube (9). A 1 g weight (10) was hung at a point 10 mm from the tip of the guide wire, and the amount of suspension at the tip of the guide wire was measured to determine the flexibility of the tip flexible portion when the guide wire was in a straight state.
[0013]
(Test method 2)
A polyethylene tube (9) having an inner diameter of 2.8 mm is fixed on a worktable at an angle of 40 ° and a radius of curvature of 20 mm, and the guide wires of Example 1 and Comparative Example 1 are inserted into the polyethylene tube (9). Then, the guide wire is fixed at a point where the tip of the guide wire projects 30 mm from the tip of the polyethylene tube (9). A 1 g weight was hung at a point 10 mm from the tip of the guide wire, and the amount of suspension at the tip of the guide wire was measured to determine the flexibility of the tip flexible portion when the guide wire was bent.
[0014]
Table 1 shows the results obtained by measuring the flexibility of the distal flexible portion of Example 1 and Comparative Example 1 by Test Methods 1 and 2. Although the flexibility of the distal end flexible portion in the straight state of Example 1 and Comparative Example 1 was almost the same, the flexibility of Comparative Example 1 was obviously impaired in the bent state. It is clear that they have sufficient flexibility.
[0015]
[Table 1]

[0016]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain a guide wire in which the rigidity of the main body is high and the flexibility of the distal end is not impaired even when bent at a small curvature.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of one embodiment of a medical guidewire of the present invention.
FIG. 2 is a cross-sectional view of a conventional medical guidewire.
FIG. 3 is a schematic view of a test bench in a test method 1 as viewed from a side.
FIG. 4 is a schematic view of the test table 2 as viewed from above the work table.
[Explanation of symbols]
1. Guide wire2. Core wire3. Coil spring4. Tip fixing part5. 5. Rear end fixing part 6. Core wire tip Tapered section8. Small diameter section 9. Polyethylene tube 10.1g weight

Claims (2)

A medical guidewire comprising a core wire and a coil spring covering the outer periphery of the core wire, wherein a pitch of at least a part of the coil spring is larger than other parts. 2. The medical guidewire according to claim 1, wherein the pitch of the coil spring at the distal end of the guide wire is larger than the pitch of the coil spring at the other portion.

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