JP2016189998A - Guide wire for catheter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a guide wire for a catheter having excellent guide property in a branch blood vessel, etc. and safety property in breaking while securing flexibility and restorability.SOLUTION: A guide wire 10 for a catheter includes: a core grid 12 having a body part 10b and a tip part 12b; and a coil part 14 for covering the outer periphery of the core grid. The body part on the proximal side of the core grid is formed by a shape memory alloy. The tip part connected to the body part and extending toward a distal side is formed by stainless steel or the bond/alloy of stainless steel and a shape memory alloy. The coil part is formed by winding stainless steel around the outer periphery of the core grid in a coil shape over the whole portion in the axial direction concerning the distal end part on the distal side of the tip part.SELECTED DRAWING: Figure 1

Description

The present invention relates to a catheter guide wire for introducing a therapeutic or examination catheter to a target site in a blood vessel, a digestive tract, or a trachea.

After the guide wire is inserted into the blood vessel together with the catheter, the guide wire is projected by a predetermined length from the distal end of the catheter and pushed forward with the distal end of the guide wire ahead of the catheter in order to reach the target blood vessel site. Therefore, the distal end portion of the guide wire is required to be flexible because it can be inserted into a meandering blood vessel or a complicated blood vessel branch without damaging the blood vessel wall.

Conventionally, there has been a guide wire for a catheter in which a coil spring is sheathed around a stainless steel wire (SUS wire (hereinafter also referred to as “core core” or “core metal”)). It did not have sex. In particular, this guide wire has a problem that once it is bent in a blood vessel or the like in the operation process, a kink is generated and the original shape is not restored while being bent.

In order to solve this problem, Ni-Ti alloy, which is a shape memory alloy that does not cause kinking and ensures flexibility, is used as a core, and a resin film such as polyurethane with low frictional resistance is applied to the core, which is made hydrophilic. Guidewires that are coated with a functional maleic acid have been provided, and the sales channel has been expanded. However, in the case of this guide wire, since the core of the core is soft, it is difficult to guide it to a target blood vessel in the case of a branched blood vessel, and the operation requires experience. Also, when the core core breaks due to metal fatigue in the blood vessel, it is necessary to remove it from the blood vessel with the broken core core remaining in the exterior of a weak material such as a resin film. was there.

JP-A-117624

The present invention was created in view of the above problems, and an object of the present invention is to provide a guidewire for a catheter that has good guideability and safety at breakage in a branching blood vessel while ensuring flexibility and restorability. And

The present invention provides a linear catheter guide wire having a cored bar having a main body part and a tip part, and a coil part enclosing the outer periphery of the cored bar.
In the catheter guide wire, the body portion on the proximal side of the metal core is formed of a shape memory alloy, and the tip portion coupled to the body portion and extending distally is formed of stainless steel or stainless steel and shape memory. Formed with bonds or alloys with alloys,
The tip portion distal to the tip portion is formed by winding stainless steel around the outer circumference of the core metal in a coil shape.

According to this catheter guide wire, the core metal as the core core is composed of the main body portion on the proximal side and the distal end portion on the distal end side, and the main body portion (the proximal portion 10b in the present embodiment) has a shape memory. The alloy and the tip (in this embodiment, the tip 10a) are formed of SUS or a bond or alloy of SUS and a shape memory alloy. Since the main body portion is formed of a shape memory alloy having superelasticity, the above-described kink does not occur, and it is advantageous in that the shape of the internal part such as a blood vessel is less likely to remain without being restored.

Further, the elasticity of the whole or a part can be adjusted at the heat input temperature during the heat treatment of the shape memory alloy, and the adjustment according to the target site can be made. In addition, since the tip is made of a hard material such as SUS, it can be inserted in a desired shape that is easy to guide even in branch vessels, etc. In the case of a shape memory alloy with SUS, the shape can be maintained by adjusting the amount. Easy to adjust the power.

Furthermore, since the coil shape is wound around the core as an exterior, the flexibility is high and the tensile strength is high, so that the possibility of breaking in the body can be greatly reduced.

Moreover, it is preferable that the front-end | tip part of the said metal core has a shape which diameter-reduces toward a front-end | tip,
Since it is tapered toward the tip, it is easy to insert.

Moreover, it is preferable that the said coil part is formed in the circular shape in the part which the front-end | tip part of the said metal core covers, and the part which the main-body part of the said metal core encloses is formed in a flat plate cross section.

As will be described in detail later, if the tip of the outer periphery (exterior) of the metal core is a round wire coil, the flexibility is high and it is easy to create a desired shape. If the main body is a flat coil, the rigidity is high and the pushing strength is high. It is possible to make the core metal with a large diameter that can secure

The shape memory alloy is preferably a Ni-Ti alloy.

The shape memory alloy and stainless steel are preferably connected after the surface treatment of coating the shape memory alloy with a Ni thin film.

Since the Ni—Ti alloy and SUS are difficult to adhere to each other, the adhesion strength between them can be increased by applying Ni plating.

Moreover, there exists an example which heat-treats 200-400 degreeC as a heat processing of the said metal core.

As described above, the cored bar is a shape memory alloy, and the tensile strength, yield strength, and spring constant can be changed depending on the heat input temperature. Therefore, the desired strength and spring constant can be obtained according to the body part, and the whole or a part of the elasticity can be easily adjusted. For example, in the case of a core of Ni-Ti alloy, if it is around 200-400 ° C., the spring constant is small and the flexibility is high, but the tensile strength / yield strength is about the same as that at room temperature to ensure the strength. Can do.

Furthermore, it is preferable that the said metal core is joined to the said coil part by the distal end part of the said front-end | tip part, the proximal end part of the said main-body part, and also at least 1 place or more.

As will be described in detail later, since the cored bar and the coil part are joined at at least one other location including both ends, it is difficult to break, and even when the cored bar breaks due to contraction of the ventricle etc. When removed, there is no risk of the broken core metal remaining in the body. Furthermore, if one point of joining other than the joining of both ends of the core metal is used as the joining point between the tip part and the body part, the joining of the tip part and the body part can be used as it is to prevent breakage and residual in the body. Production costs and time can be reduced without the need for a separate process.

As described above, according to the catheter guide wire of the present invention, flexibility and resilience are ensured, and elastic adjustment according to the target site is easy. It is an object of the present invention to provide a catheter guide wire with good safety.

It is sectional drawing along the axial direction of the guide wire for catheters concerning embodiment of this invention. 1A is a sectional view taken along line AA in FIG. 1, and FIG. 1B is a sectional view taken along line BB in FIG. It is a schematic diagram which shows the difference of the outer diameter and internal diameter in the exterior of a core core front-end | tip part and a hand part, (a) is the round wire which is the armor of a front-end | tip part, (b) is the flat plate which is the armor of a hand part The difference between the outer diameter and inner diameter of the wire is shown. Further, (c) shows a schematic enlarged view of region A in (b). It is a graph which shows the heat processing characteristic of the tensile strength and the yield strength of a SUS line and a Ni-Ti alloy wire. It is a graph which shows the heat processing characteristic in the spring constant of a SUS line and a Ni-Ti alloy wire.

Hereinafter, specific embodiments of the guide wire for a catheter of the present invention will be described in detail with reference to the drawings. In addition, embodiment shown how is illustration enumeration, it is not limited to this.

FIG. 1 is a cross-sectional view along the axial direction of a guide wire 10 according to an embodiment of the present invention, FIG. 2A is a cross-sectional view taken along line AA of FIG. 1, and FIG. The line BB sectional drawing is shown. The guide wire 10 is exemplified by a guide wire 1 for expanding a heart valve.

In FIG. 1, the right side shows the hand side and the left side shows the tip side, and the left side is shown short for the sake of space, but actually extends long to the hand side. The guide wire 10 has a core core 12, an outer sheath 14 around the core core, and a surface layer 16 around the outer sheath 14 in the radial direction from the axis OO. Further, the guide wire 10 has a different configuration on the distal end side and the proximal side, and here, shown as a distal end portion 10a and a proximal portion 10b, respectively.

As shown in FIG. 1, the tip side 10a having a role of guiding the guide wire 10 at the head (distal side) in a blood vessel or the like has a core core 12 of SUS or the like (generally SUS304) as shown in FIG. A flat steel wire member 12b and a shape memory alloy 12a such as a Ni-Ti alloy are bonded to each other. In FIG. 1, as indicated by lines 13 and 15, the diameter of the core core 12 decreases toward the distal end side. Further, the proximal side of the SUS member 12b is bonded from a predetermined position of the Ni—Ti member 12a of the tip portion 10a and extends to the tip side, and the bonding start position on the proximal side of the Ni—Ti member 12a is between the exterior 14 and the Ni. -A position having a thickness of the SUS member 12b between the Ti member 12a (gap 19). Therefore, the core core 12 increases in the amount of SUS with respect to Ni—Ti toward the distal end side, and is generally composed of SUS at the most advanced.

As shown in FIG. 2A, the Ni-Ti member 12a has Ni plating 17 applied on the surface thereof. The Ni—Ti alloy has a property that it is difficult to adhere to SUS. On the other hand, Ni has the property of being easily bonded to SUS. For this reason, in order to adhere the Ni-Ti member 12a and the SUS member 12b, Ni plating 17 is applied to the surface side of the Ni-Ti member 12a which is easily Ni-plated.

The outer sheath 14b around the core core 12 of the tip 10a is formed by winding a round wire SUS (SUS304) in a coil shape. Coiled steel wires are advantageous in that they are highly elastic and easy to bend while being difficult to break. In addition, when a round wire is used, each round wire adjacent in the axial direction comes into contact with a circle contact, and the surface also comes into contact with a circle contact or an arc, so that the possibility of damaging the body wall with a corner is low. In addition, the relationship between the guide wire 10 and its diameter by the exterior 14a being a round wire coil will be described later.

Next, as shown in FIG. 1 and FIG. 2B, the proximal portion 10b of the guide wire 10 will be described. The proximal portion 10b is positioned on the proximal side of the distal end portion 10a, and is inserted and removed following the distal end portion 10a that guides the inside of a blood vessel or the like. Although not shown in FIG. 1, the proximal side of the hand portion 10 b (distant to the right side in FIG. 1) is grasped by a hand of a doctor or the like, and a pushing force or a drawing force is applied.

The hand portion 10b is provided with a core core 12a in the radial direction from the axis OO in the same manner as the distal end portion 10a, an exterior 14b around the core core 12a, and a cover 16 around the exterior 14b. The core core 12a is a Ni—Ti alloy wire formed integrally and continuously with the core core 12a of the distal end portion 10a. As shown in FIGS. 1 and 2B, the core core 12a is formed of Ni—Ti wires 12a filled in the inner diameter of the exterior 14 over substantially the entire area.

Further, the outer sheath 14b around the core core 12a of the hand portion 10b is formed by winding a SUS (SUS304) steel wire of a flat wire in a coil shape. As described above, the round line is advantageous from the viewpoint of contact with the blood vessel wall or the like, but the influence is considered to be smaller than that of the leading end portion 10a. In the exterior 14b of the hand portion 10b, priority is given to ensuring the rigidity of the core core 10a.

The rigidity is increased as the diameter of the core core 12a is increased. Therefore, in order to ensure rigidity, it is necessary to increase the diameter. Since the outer diameter of the guide wire 10 itself is desired according to the target blood vessel equal diameter, in order to increase the outer diameter of the core core 14b, it is necessary to increase the inner diameter in the same exterior 14b. At this time, since the exterior 14b can be disposed adjacent to each other without a gap, the flat plate wire is thinner and the rigidity can be secured. Therefore, the outer diameter of the core 14b itself, which can increase the inner diameter of the exterior 14b, can be increased, and as a result, the rigidity of the hand portion 10b can be ensured.

This is schematically shown in FIG. (A) shows the difference between the outer diameter OD and the inner diameter ID of the round wire that is the exterior 14a of the tip portion 10a, and (b) the flat wire that is the exterior 14b of the proximal portion 10b. As can be understood from these (a) and (b), the inner diameter ID (= r1) in the case of a round wire and the case of a flat wire with respect to the outer diameter OD (= R) required and fixed according to the body part It can be seen that the relationship with the inner diameter ID (= r2) of R has a relationship of R> r2> r1.

FIG. 3C shows a schematic enlarged view of the area A in FIG. 3B. If the exterior 14b of the proximal portion 12b of the core core 12 is a flat wire, the surface may be rattled. It is understood that it is preferable in terms of securing the inner diameter (securing the core core rigidity) but not preferable in terms of damaging the body wall at the tip portion guided by the tip of the body and acting on the pushing force as described above. The cover 16 will be described later).

Further, as shown in FIG. 1, in the guide wire 10, the core core 12 is integrally connected by a connecting portion 21 between a distal end portion 12a and a proximal portion 12b. The distal end portion 12a and the proximal portion 12b are connected by brazing or welding. As a result, the Ni—Ti alloy wire 12a and the SUS wire 12b are not only bonded with an adhesive, but also provided with a location where the Ni—Ti alloy wire 12a and the SUS wire 12b are fixed by brazing or the like.

In FIG. 1, the SUS wire 12b and the Ni—Ti alloy wire 12a are adhesively bonded to the distal end portion 12a, and the proximal portion 12b is composed of the Ni—Ti alloy wire 12a. You may comprise only the wire 12b or the alloy of the SUS wire 12b and the Ni-Ti alloy wire 12a. The Ni—Ti alloy wire 12a may be another shape memory alloy.

Further, the distal end side 14a and the proximal side 14b of the outer casing 14 are integrally coupled to each other at the position of the connecting portion 21 by brazing or welding. At this time, the above-described core core 12 is brazed together with brazing or welding. The exterior 14 may be bonded to the surfaces of the tip 12a and the hand 12b of the core core 12 (brazing etc. other than the connecting portion 21 will be described later).

In addition, the core core 12 and the outer sheath 14 are sealed by brazing, welding, or the like at the distal tip portion 23 and the proximal rear end portion (hand side rear end portion) 22. The core core 12 and the exterior 14 are sealed and joined at at least three locations of the connecting portion 21, the distal tip portion 23, and the proximal rear end portion 22. Accordingly, even when the core core 12 is broken in the body (in a blood vessel or the like) due to metal fatigue or the like, the exterior 14 is joined by the SUS coil that expands and contracts in the axial direction, and is easily expanded and contracted together with the core core 12. Is difficult to break, and even if the core core 12 breaks, if the outer sheath 14 is removed, the core core 12 inside it is also removed, and there is no possibility of remaining in the body. Safety is high in this respect.

In addition, since the core core 12 and the exterior 14 are joined by the connecting portions 21 other than both ends, bending fatigue is particularly generated in the vicinity of the tip portion 12a of the core core 12 where the number of bending is large and fatigue is large. Since it is divided into bending fatigue between the distal end portion 23 and between the connecting portion 21 and the proximal distal end portion 22, the structure is difficult to break. Further, since the metal joining process such as brazing at the connecting part 21 and the distal tip part 23 and the proximal rear end part 22 is a process necessary for joining the core core 12 and the sheath 14 in the first place, In addition, a part of the normal manufacturing process of the guide wire 10 can be used for preventing breakage and remaining in the body.

Further, a coating is made around the exterior 14. For this coating, a resin material with low bioinvasiveness such as Teflon (registered trademark) is used.

Next, material characteristics of the SUS wire 12a used on the distal end side of the core core 12 and the Ni-Ti wire 12b used on the almost proximal side will be described. FIG. 4 shows the heat treatment characteristics in terms of strength between the SUS wire 12a and the Ni—Ti wire 12b, and FIG. 5 shows the heat treatment characteristics at the spring constant of the SUS wire 12a and the Ni—Ti wire 12b. ing. Here, SUS304 has a diameter φ = 0.46 mm as the SUS wire, and Ni—Ti wire has a diameter φ = 0.60 mm. In addition, the heating temperature is defined as heat input for 30 minutes.

As shown in the graph of FIG. 4, in SUS304, the yield strength = 2100 N / mm 2 and the tensile strength = 2366 N / mm 2. In Ni-Tt, until the heat input is 400 ° C., the yield strength is 599 N / mm 2 and the tensile strength is about 1509 N / mm 2, both of which are almost independent of temperature, but the heat input exceeds 400 ° C. It can be seen that the yield strength is reduced to 1000 N / mm 2 or less and the tensile strength is reduced to 100 N / mm 2 or less.

Next, as shown in the graph of FIG. 5, in SUS304, the spring constant is 0.4 N / mm, whereas in Ni-Ti, the spring constant decreases as the heat input temperature increases. It is understood that the decrease stops at 350 to 400 ° C., increases from around 400 ° C., and becomes larger than when no heat is input.

As can be understood from FIGS. 4 and 5, Ni—Ti can easily change its strength (tensile strength, yield strength) and spring constant according to the heat treatment. Therefore, when a Ni-Ti wire is used for the proximal portion 12a of the core core 12, desired elasticity and strength suitable for the body part and application can be easily provided. Moreover, it is easy not only to heat the entire core portion 12a of the core core 12 but also to heat only a part of the core core 12 and change the elasticity and strength of the portion and other portions. That is, partial elasticity / strength adjustment is easy.

For example, when the temperature is around 300 to 400 ° C., the spring constant is small and the flexibility is high, but it is understood that the tensile strength / yield strength is about the same as that at room temperature and the strength can be secured.

As mentioned above, although embodiment about the guide wire for catheters of this invention was described, this invention is not limited to this, In the range which does not deviate from the mind and teaching as described in a claim, a description, etc. Those skilled in the art will understand that other variations and improvements can be obtained. For example, it can be used for non-catheter guidewires

10 Guide wire 10a Tip portion 10b Hand portion (main body portion)
12 Core core (core metal)
12a Hand portion 12b Tip portion 14 Exterior (coil)
14a Round wire coil 14b Flat plate coil 16 Surface 17 Plating 21 Connecting part

Claims (7)

A linear catheter guide wire having a core part having a main body part and a tip part, and a coil part enclosing the outer periphery of the core part,
A body portion on the proximal side of the metal core is formed of a shape memory alloy, and a distal end portion coupled to the body portion and extending to the distal side is made of stainless steel or a combination or alloy of stainless steel and a shape memory alloy. Formed,
The coil portion is
A guide wire for a catheter, characterized in that stainless steel is wound around the outer periphery of the core bar in a coil shape around the entire axial direction. The guide wire for a catheter according to claim 1, wherein the distal end portion of the cored bar has a shape that decreases in diameter toward the distal end. In the coil portion, a portion to be encapsulated at a tip end portion of the core metal is formed in a circular shape, and a portion to be encapsulated in a main body portion of the core metal is formed in a flat plate cross section. Item 3. A catheter guidewire according to Item 2. The guide wire for a catheter according to any one of claims 1 to 3, wherein the shape memory alloy is a Ni-Ti- containing alloy. The guide wire for a catheter according to claim 4, wherein the shape memory alloy and the stainless steel are connected after the surface treatment for coating the shape memory alloy with a Ni thin film. The guide wire for a catheter according to claim 4 or 5, wherein the core metal is subjected to heat treatment at 200 to 400 ° C. The said metal core is joined to the said coil part by the distal end part of the said front-end | tip part, the proximal end part of the said main-body part, and at least 1 place or more. Item 7. The catheter guide wire according to any one of Items 1 to 6.