JP6987260B2 - Medical guide wire - Google Patents

Description

The present invention relates to a medical guide wire having a core wire having a tip made of a superelastic alloy and a coil spring mounted on the outer periphery of the tip of the core wire.

As a guide wire used when treating lesions in the lower limb blood vessels by the crossover method, the tip made of a superelastic alloy such as Ni—Ti alloy and the base end made of a metal material such as stainless steel are joined. There has been proposed a guide wire provided with a core wire and a coil spring mounted on the outer periphery of the tip of the core wire (Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-141461

For example, in order to prevent perforation (perforation) of a blood vessel when the guide wire is inserted into the blood vessel toward a lesion of a blood vessel of the lower limb, the tip of the guide wire is brought into contact with the inner wall of the blood vessel. An operation called a knuckle wire technique is performed in which the vicinity of the tip is bent so that the tip faces the base end side.

However, it is difficult to bend the conventional guide wire including the above-mentioned Patent Document 1 at a predetermined position.
In addition, since the radius of curvature of the bent portion is large, the resistance when pushing the guide wire toward the blood vessel or the lesion portion with this portion at the head increases, and it may not be possible to pass through the hard lesion portion.

The present invention has been made based on the above circumstances, and an object of the present invention is that it can be bent at a predetermined position near the tip in a blood vessel and has a small radius of curvature with this position as an apex. It is to provide a guide wire capable of forming a (sharp) bent shape.

(1) The medical guide wire of the present invention has a core wire having a tip made of a superelastic alloy and a coil spring mounted on the outer periphery of the tip of the core wire.
At the tip of the core wire, the following conditions are satisfied between the first position and the second position on the base end side thereof, the diameter is expanded at a substantially constant ratio, and the first position I is the tip. It is characterized in that only one tapered portion with the second position II as the base end is formed.

(conditions)
0.003 ≦ (D2-D1) / (L2-L1) ≦ 0.012
・ 0.05mm ≤ D1 ≤ 0.1mm
・ 3mm ≤ L1 ≤ 20mm
・ 5 mm ≤ L2-L1 ≤ 30 mm

Here, L1: the distance from the tip of the core wire at the first position.
L2: Distance from the tip of the core wire at the second position
D1: Diameter of the core wire at the first position
D2: Diameter of the core wire at the second position

According to the medical guide wire having such a configuration, the diameter of the core wire rapidly increases from the first position (the tip of the tapered portion) to the second position (the base end of the tapered portion). In the blood vessel, for example, by abutting the tip of the guide wire against the inner wall of the blood vessel and bending the tip portion, it is possible to surely form a bent shape having a small radius of curvature with the first position as the apex.

Since the radius of curvature of the formed bent shape is small, the resistance when the guide wire is pushed toward the blood vessel or the lesion with the first position, which is the apex of the bent shape, is also small, and even if the lesion is hard. Can pass.

(2) In the medical guide wire of the present invention, the core wire is joined to the tip end portion and a base end portion made of a metal material having a lower elastic modulus and higher strength than the superelastic alloy constituting the tip portion. It is preferable to be.

(3) In the medical guide wire of (2) above, it is preferable that the tip end portion of the core wire is made of a Ni—Ti alloy and the base end portion is made of stainless steel.

(4) In the medical guide wire of the above (3), the length of the core wire is preferably 1500 to 3000 mm, and the length of the tip portion thereof is preferably 100 to 300 mm.

According to the medical guide wire having such a configuration, the length of the base end portion to the total length of the core wire can be sufficiently secured, so that the rigidity of the guide wire as a whole becomes high, and excellent pushability and torque are obtained. Transmissibility can be ensured.

(5) In the medical guide wire of the present invention, the outer diameter of the coil spring at a position 20 mm from the tip is preferably 0.011 inch or less, particularly preferably 0.010 inch or less.

According to the medical guide wire having such a configuration, the passability when pushing into a blood vessel or a lesion is further improved.

(6) The medical guide wire of the present invention can be suitably used in the treatment of subknee (BTK) lesions by the ipsilateral antegrade approach.

According to the medical guide wire of the present invention, it is possible to surely form a bent shape having a small radius of curvature (R) with the first position as an apex in the blood vessel.
As a result, it is possible to prevent perforation of the blood vessel by pushing it toward the blood vessel or lesion with the first position at the beginning, and the resistance when pushing toward the blood vessel or lesion is reduced, so that even a hard lesion can pass through. can do.

It is a front view which shows one Embodiment of the guide wire of this invention. It is a partial cross-sectional front view of the guide wire shown in FIG. It is explanatory drawing of the core wire which constitutes the guide wire shown in FIG. It is a partially enlarged view of the core wire shown in FIG. It is a graph which shows the axial change of the bending load about the guide wire obtained in Example 1 and Comparative Examples 1-6.

The medical guide wire 100 of the present embodiment shown in FIGS. 1 to 4 has a core wire 10 to which a tip portion 11 made of a superelastic alloy and a base end portion 12 made of stainless steel are joined, and the tip of the core wire 10. It has a coil spring 20 mounted on the outer periphery of the tip portion of the portion 11.

The length of the core wire 10 (tip portion 11 and base end portion 12) is preferably 1500 to 3000 mm, more preferably 2200 to 2600 mm, and a suitable example is 2350 mm.

As shown in FIGS. 3 and 4, the tip portion 11 of the core wire 10 has a first taper between the first position I and the second position II, which satisfies the conditions of the present invention and expands in diameter at a constant ratio. A portion 111 is formed (the first position I and the second position II are connected by the first tapered portion 111).

Further, on the tip end side of the first tapered portion 111, a first straight portion 1101, a tapered portion 1102, and a plate-shaped portion 1103 are formed from the first position I toward the tip end direction.
Further, on the proximal end side of the first tapered portion 111, the second tapered portion 112, the third tapered portion 113, the second straight portion 114, the fourth tapered portion 115, and the like from the second position II toward the proximal end direction. The third straight portion 116 is formed.

The first tapered portion 111 is a tapered portion that connects the first position I and the second position II (with the first position I as the tip and the second position II as the base end).
The separation distance L1 of the first position I from the tip of the core wire 10 is usually 3 to 20 mm, preferably 12 to 16 mm, and a suitable example is 14 mm.

If the separation distance L1 is less than 3 mm, it becomes difficult to form a bent shape.
On the other hand, when the separation distance L1 exceeds 20 mm, the small-diameter portion located on the distal end side of the first position I becomes too long, so that it is easily trapped by the lesion. Further, it is not possible to form a bent shape having a small radius of curvature (see Comparative Example 2 described later).

The diameter D1 of the core wire 10 at the first position I is usually 0.05 to 0.1 mm, preferably 0.07 to 0.08 mm, and a suitable example is 0.075 mm.

If the diameter D1 is less than 0.05 mm, the strength of the tip portion including the portion located on the tip side of the first position I cannot be sufficiently secured.
On the other hand, if the diameter D1 exceeds 0.1 mm, the effect of preventing perforation of blood vessels due to the bent shape cannot be sufficiently exerted.

The axial length (L2-L1) of the first tapered portion 111 is usually 5 to 30 mm, preferably 10 to 20 mm, and a suitable example is 15 mm.

If the axial length (L2-L1) is less than 5 mm, the diameter of the first tapered portion 111 cannot be sufficiently expanded, D2 becomes too small, and a bent shape having a small radius of curvature cannot be formed. In addition, the flexural rigidity is low over the entire length and the supportability is also inferior (see Comparative Example 3 described later).

On the other hand, when the axial length (L2-L1) exceeds 30 mm, the radius of curvature of the bent shape becomes extremely large. In addition, the tip portion is inferior in flexibility and has insufficient supportability (see Comparative Example 4 described later).

In the first taper portion 111, the diameter expansion ratio (D2-D1) / (L2-L1) is 0.003 to 0.012, preferably 0.004 to 0.006, and 0. It is said to be 0051.

If the diameter expansion ratio (D2-D1) / (L2-L1) is less than 0.003, the diameter cannot be sufficiently expanded in the first tapered portion 111, D2 becomes too small, and the radius of curvature is small (sharp). ) It is not possible to form a bent shape (see Comparative Example 5 described later).

On the other hand, when this diameter expansion ratio exceeds 0.012, the radius of curvature of the bent shape becomes extremely large. Further, the flexibility of the tip portion is inferior (see Comparative Example 6 described later). Further, the apex of the bent portion may be located closer to the base end side than the first position I, and it may not be possible to form a bent shape having the first position as the apex (see Comparative Example 2 described later).

The diameter D2 of the core wire 10 at the second position II is preferably 0.11 to 0.23 mm, more preferably 0.14 to 0.16 mm, and a suitable example is 0.152 mm.

At the tip of the core wire constituting the medical guide wire of the present invention, there is only one tapered portion (first tapered portion 111 in the present embodiment) having a diameter expansion ratio of more than 0.003.
Further, a tapered portion having a diameter expansion ratio of less than 0.003 may be formed at the tip of the core wire constituting the medical guide wire of the present invention.

An example of suitable dimensions of the tip portion 11 of the core wire 10 constituting the medical guide wire 100 of the present embodiment is as follows.

Plate-shaped portion 1103 and tapered portion 1102: length = 11 mm
・ First straight portion 1101: Diameter = 0.075 mm
: Length = 3mm
First taper portion 111: Diameter of tip (first position) = 0.075 mm
: Diameter of base end (second position) = 0.152 mm
: Length = 15mm
: Diameter expansion rate = 0.0051
Second taper portion 112: Diameter of tip (second position) = 0.152 mm
: Base end diameter = 0.196 mm
: Length = 27mm
: Diameter expansion rate = 0.0016
3rd taper portion 113: Tip diameter = 0.196 mm
: Base end diameter = 0.220 mm
: Length = 40mm
: Diameter expansion rate = 0.0006
-Second straight part 114: Diameter = 0.220 mm
: Length = 30mm
4th taper portion 115: tip diameter = 0.220 mm
: Base end diameter = 0.310 mm
: Length = 40mm
: Diameter expansion rate = 0.0023
・ Third straight part 116: Diameter = 0.310 mm
: Length = 30mm

The length of the tip portion 11 is preferably 100 to 300 mm, more preferably 150 to 250 mm, and a suitable example is 196 mm.
As a result, it is possible to exhibit sufficient flexibility and durability as a guide wire used for the treatment of subknee (BTK) lesions by the ipsilateral antegrade approach, and the length of the proximal end 12 is sufficient. Can be secured.

Examples of the superelastic alloy constituting the tip portion 11 include Ni—Ti alloys, Cu—Zn alloys, Ni—Al alloys, and the like, of which Ni—Ti alloys are preferable.

As shown in FIGS. 2 and 3, the base end portion 12 of the core wire 10 has a straight portion 120, a tapered portion 121, and a base end portion 11 (third straight portion 116) from the base end toward the base end side. The straight portion 122 is formed.

The outer diameter of the base end portion 12 (straight portion 122) is usually 0.018 inches or less, and a suitable example is 0.014 inches.
The length of the base end portion 12 is preferably 1300 to 2800 mm, more preferably 2000 to 2300 mm, and a suitable example is 2154 mm.
As a result, the length of the base end portion 12 in the total length of the core wire 10 can be sufficiently secured, so that the rigidity of the guide wire 10 as a whole becomes high, and excellent pushability and torque transmission are ensured. Can be done.

As the stainless steel constituting the base end portion 12, all the stainless steels constituting the core wire of the conventionally known guide wire can be used, for example, SUS304, SUS303, SUS316, SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430, SUS434, SUS444, SUS429, SUS430F, SUS302 and the like can be mentioned.

A water-repellent resin layer (not shown) is formed on the outer peripheral surface of the base end portion 12.
As the resin constituting the water-repellent resin layer, all resins used for medical purposes and having water repellency can be used, and examples of suitable resins include fluororesins such as PTFE.

In the present embodiment, the tip portion 11 and the base end portion 12 are joined by welding, but the joining method between the tip portion and the base end portion constituting the core wire is not limited to this.

The coil spring 20 constituting the medical guide wire 100 of the present embodiment is attached to the outer periphery of the tip portion of the tip portion 11 of the core wire 10 along the axial direction.
The coil spring 20 includes a tip end side coil 21 and a base end side coil 22.
The length of the coil spring 20 is preferably 50 to 250 mm, and a suitable example is 120 mm.

The tip side coil 21 is made of an X-ray impermeable substance such as platinum or a platinum alloy.
The length of the tip coil 21 is preferably 20 to 50 mm, and a suitable example is 30 mm.
The tip side coil 21 includes a tip side small diameter portion 211 (a length of 20 mm from the tip), a taper portion 212, and a base end side large diameter portion 213.
The coil outer diameter of the tip side small diameter portion 211 is usually 0.011 inch or less, and a suitable example is 0.010 inch.
The coil outer diameter of the base end side large diameter portion 213 is usually 0.018 inch or less, and a suitable example is 0.014 inch.

The base end side coil 22 is made of stainless steel.
The length of the base end side coil 22 is preferably 10 to 200 mm, and a suitable example is 90 mm.
The coil outer diameter of the base end side coil 22 is usually 0.018 inch or less, and a suitable example is 0.014 inch.

The tip portion, the middle portion, and the rear end portion of the coil spring 20 are fixed to the outer periphery of the tip portion of the tip portion 11 of the core wire 10 by solders 31, 32, 33, respectively.
The inside of the coil spring 20 is filled with a cured resin, and a resin layer (a layer of a cured resin that coats the coil wire) is formed on the outer periphery thereof, and the surface of the resin layer is hydrophilic. The resin coating layer is laminated and formed.

<Example 1>
The medical guide wire of the present invention having the shapes shown in FIGS. 1 to 4 and having the individual dimensions shown as a suitable example was manufactured.

<Comparative Examples 1 to 6>
A guide wire for comparison provided with a core wire having the shape (dimensions) shown in Table 1 below and a coil spring similar to that of the first embodiment was prepared. Here, Comparative Example 1 and Comparative Example 2 are conventional products.
Regarding the tapered portion at the tip of the core wire (when there are multiple portions, the one with the maximum expansion ratio), L1, L2, L2-L1, D1, D2, D2-D1, (D2-D1) / (L2-L1) ), The length of the tip made of Ni—Ti alloy, and the length of the base made of stainless steel are shown in Table 1 below.

<Measurement of vertex position and radius of curvature of bent shape>
Each of the medical guide wires obtained in Example 1 and Comparative Examples 1 to 6 was formed into a bent shape by a rotation and push-pull operation (knuckle wire technique) in a tube having an inner diameter of 20 mm that imitated a blood vessel.

For the bent shape formed in this way, the distance from the tip of the guide wire at the apex position was measured, and the radius of curvature was measured by drawing an approximate circle using a measuring microscope. The results are also shown in Table 1 below.

Here, the "tip of the guide wire" is the tip of the solder (solder 31 shown in FIGS. 1 and 2) for fixing the tip of the coil spring to the core wire constituting the core wire, and is 1 mm from the tip of the core wire. It is located on the tip side.

As shown in Table 1, the guide wire obtained in Example 1 was bent with the first position as the apex, and its radius of curvature was 0.78 mm, which was sufficiently small.

<Evaluation of flexibility and support of the tip>
For each of the guide wires according to Example 1 and Comparative Examples 1 to 6, the distance between the fulcrums was set to 20 mm, and the bending load was measured along the length direction when a bending load was applied in the middle to bend the guide wires by 2 mm. Then, the relationship between the distance from the tip of the guide wire and the bending load (strength of the waist) was obtained. The results are shown in FIG.

As shown in FIG. 5, the guide wire obtained in Example 1 exhibits appropriate flexibility in the tip portion from the tip to about 130 mm, and is sufficiently high in the portion on the base end side of the tip portion. It has bending rigidity. It can be said that such a guide wire is also excellent in supportability (pushability and torque transmission).

On the other hand, the guide wires obtained in Comparative Example 1 and Comparative Example 4 have either flexibility at the tip portion up to about 130 mm from the tip and flexural rigidity (supportability) at the portion on the proximal end side. Is inferior to the guide wire obtained in Example 1.
Further, the guide wires obtained in Comparative Example 2 and Comparative Example 3 have low bending rigidity over the entire length thereof and are inferior in supportability.

For each of the guide wires obtained in Examples 1 and Comparative Examples 1 to 6, the flexibility at the tip portion from the tip to about 130 mm and the flexural rigidity (supportability) at the portion on the proximal end side thereof are set in three stages. (○: Good, Δ: Insufficient, ×: Poor) was evaluated. The results are also shown in Table 1 below.

100 Medical guide wire 10 Core wire 11 Core wire tip 1101 1st straight part 1102 Tapered part 1103 Plate-shaped part 111 1st tapered part 112 2nd tapered part 113 3rd tapered part 114 2nd straight part 115 4th tapered part 116 3rd straight part 12 Core wire base end part 120 Straight part 121 Tapered part 121
122 Straight part 20 Coil spring 21 Tip side coil 22 Base end side coil 211 Tip side small diameter part 212 Tapered part 213 Base end side large diameter part 31, 32, 33 Solder

Claims (6)

It has a core wire having a tip made of a superelastic alloy and a coil spring mounted on the outer periphery of the tip of the core wire.
At the tip of the core wire, the following conditions are satisfied between the first position and the second position on the base end side thereof, the diameter is expanded at a substantially constant ratio, and the first position I is the tip. The medical guide wire is characterized in that only one tapered portion with the second position II as the base end is formed.
(conditions)
0.003 ≦ (D2-D1) / (L2-L1) ≦ 0.012
・ 0.05mm ≤ D1 ≤ 0.1mm
・ 3mm ≤ L1 ≤ 20mm
・ 5 mm ≤ L2-L1 ≤ 30 mm
Here, L1: the distance from the tip of the core wire at the first position.
L2: Distance from the tip of the core wire at the second position
D1: Diameter of the core wire at the first position
D2: Diameter of the core wire at the second position The first aspect of the core wire is characterized in that the tip portion is joined to a base end portion made of a metal material having a lower elastic modulus and higher strength than the superelastic alloy constituting the tip portion. The medical guide wire described. The medical guide wire according to claim 2, wherein the tip portion of the core wire is made of a Ni—Ti alloy and the base end portion is made of stainless steel. The medical guide wire according to claim 3, wherein the core wire has a length of 1500 to 3000 mm, and the tip portion thereof has a length of 100 to 300 mm. The medical guide wire according to any one of claims 1 to 4, wherein the outer diameter of the coil spring at a position 20 mm from the tip is 0.011 inch or less. The medical guidewire according to any one of claims 1 to 5, which is used in the treatment of subknee (BTK) lesions by an ipsilateral antegrade approach.

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