Patent Description:
Methods using a catheter are widely implemented as a method for treating or examining a constricted part or occluded part (hereinafter referred to as "lesion") in a blood vessel, or the like. Typically, guide wires are used to guide the catheter to the lesion in the blood vessel, or the like. The guide wire needs to be able to enter the blood vessel along the curvature of the blood vessel, and a distal end portion of the guide wire needs to have flexibility. When the lesion hardens due to calcification, or the like, and the distal end portion of the guide wire gets stuck in the lesion, the load is applied to the distal end portion of the guide wire so as to remove the distal end portion of the guide wire from the lesion, and therefore it is necessary to prevent the breakage of the distal end portion of the guide wire.

The guide wire includes a core shaft and a tip joined to a distal end of the core shaft. In some guide wires, the core shaft has a superelastic property, and further a safety wire is provided (see, for example, Patent Literature <NUM>). The safety wire made of a non-superelastic material is arranged parallel to the distal end portion of the core shaft made of a superelastic material such as NiTi, the distal end of the safety wire is joined to the tip, and the rear end of the safety wire is joined to the core shaft. Even when the core shaft is broken, the broken portion may be prevented from remaining in the body as the broken part is coupled to a main body of the core shaft via the safety wire.

In the conventional configuration including the safety wire, the flexibility of the distal end portion of the guide wire and the safety wire has not been fully considered. The conventional configuration described above includes the safety wire to safely extract the distal end portion of the guide wire after the distal end portion of the core shaft is broken. In this conventional configuration, the core shaft is broken before the break of the safety wire, and then the safety wire bears the tensile load when the guide wire is removed from the lesion, and in order not to break the safety wire due to the tensile load, the safety wire needs to have a large outer diameter. As the flexibility of the safety wire decreases in accordance with an increase in the outer diameter, there is a possibility of a reduction in the flexibility of the distal end portion of the guide wire due to the presence of the safety wire.

This description discloses the technology that may provide a solution to the issue described above.

The technology disclosed in this description may be implemented as the aspects below, for example.

The technology disclosed in this description may be realized in various forms, for example, in the form of a guide wire, a manufacturing method thereof, etc..

<FIG> is an explanatory diagram schematically illustrating a configuration of a guide wire <NUM> according to the present embodiment. <FIG> illustrates a configuration of a longitudinal cross-section (YZ cross-section) of the guide wire <NUM>. <FIG> illustrates a side configuration for portions of the guide wire <NUM> other than a coil body <NUM> described below. Apart of the guide wire <NUM> is not illustrated in <FIG>. In <FIG>, a Z-axis positive direction side is a distal end side (far side) inserted into the body, and a Z-axis negative direction side is a proximal end side (near side) manipulated by a technician such as a physician. <FIG> illustrates a state where the guide wire <NUM> has a straight shape substantially parallel to a Z-axis direction as a whole, but the guide wire <NUM> is flexible enough to be curved.

In this description, for convenience of explanation, the guide wire <NUM> is assumed to be in the state illustrated in <FIG>, and the Z-axis direction is referred to as the "axial direction of the guide wire <NUM>" or simply as the "axial direction".

The guide wire <NUM> is an elongated medical device inserted into a blood vessel, or the like, to guide a catheter into a lesion (constricted part or occluded part) in the blood vessel, or the like. The total length of the guide wire <NUM> is, for example, approximately <NUM> or more and <NUM> or less, and the outer diameter of the guide wire <NUM> is, for example, approximately <NUM> or more and <NUM> or less.

The guide wire <NUM> includes a core shaft <NUM>, the coil body <NUM>, a tip <NUM>, and an auxiliary wire <NUM>.

The core shaft <NUM> is an elongated member whose distal end side has a small diameter and proximal end side has a large diameter. More specifically, the core shaft <NUM> includes a rod-shaped small diameter portion <NUM>, a rod-shaped large diameter portion <NUM> that is located on the proximal end side with respect to the small diameter portion <NUM> and has a diameter larger than that of the small diameter portion <NUM>, and a tapered portion <NUM> that is located between the small diameter portion <NUM> and the large diameter portion <NUM> and has a diameter gradually increasing from a boundary position with the small diameter portion <NUM> to a boundary position with the large diameter portion <NUM>. According to the present embodiment, the outer diameter of the small diameter portion <NUM> is smaller than the outer diameter of the distal end of the tapered portion <NUM>. As the small diameter portion <NUM> of the core shaft <NUM> is thin as described above, high flexibility of the small diameter portion <NUM> is ensured. The shape of the cross-section (XY cross-section) at each position of the core shaft <NUM> may be any shape, such as a circular shape or a flat-plate shape. The outer diameter of the large diameter portion <NUM> is, for example, approximately <NUM> or more and <NUM> or less. The outer diameter of the small diameter portion <NUM> is, for example, approximately <NUM> pm or less.

The core shaft <NUM> has a pseudoelastic property. The pseudoelastic property here refers to the apparent elastic property that occurs in a mechanism such as twinning deformation other than the elasticity resulting from changes in interatomic spacing and include shape memory effect and superelasticity (transformation pseudoelasticity or twinning pseudoelasticity). The examples of the material for forming the core shaft <NUM> include Ni-Ti alloys having a pseudoelastic property, Ni-Ti based alloys, etc. More specifically, they are superelastic metals (Ni-Ti alloys), work-hardened Ni-Ti based alloys, wide strain range elastic Ni-Ti based alloys, linear elastic Ni-Ti based alloys, etc. Ni-Ti alloys having a pseudoelastic property and Ni-Ti based alloys are Ni-Ti alloys in which the Ni content is <NUM> at% or more and <NUM> at% or less and the remainder is Ti, Ni-Ti based alloys in which the Ni content is <NUM> at% or more and <NUM> at% or less, the content of one or more of Cr, Fe, Co, Mo, V, and Al is <NUM> at% or more and <NUM> at% or less, and the remainder is Ti, Ni-Ti based alloys in which the Ni content is <NUM> at% or more and <NUM> at% or less, the Cu content is <NUM> at% or more and <NUM> at% or less, and the remainder is Ti, etc. The entire core shaft <NUM> may be made of the same material, or each portion may be made of a different material from each other. For example, the distal end portion of the core shaft <NUM> may be made of a material having a pseudoelastic property, and the other portions may be made of materials having no pseudoelastic property.

The coil body <NUM> is a coiled member formed in a hollow cylindrical shape by spirally winding a strand. The coil body <NUM> is wound around a portion of the core shaft <NUM> on the distal end side. The portion of the guide wire <NUM> around which the coil body <NUM> is wound is primarily a portion inserted into the body. According to the present embodiment, the coil body <NUM> has the configuration of one strand tightly wound.

As the material for forming the coil body <NUM>, known materials are used, such as metallic materials, more specifically, stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, piano wires, nickel-chromium based alloys, cobalt alloys, tungsten, and the like, are used.

The tip <NUM> is a member that joins the distal end of the core shaft <NUM> and the distal end of the coil body <NUM>. Specifically, the distal end of the core shaft <NUM> and the distal end of the coil body <NUM> are firmly attached so as to be embedded inside the tip <NUM>. The outer peripheral surface of the tip <NUM> on the distal end side is a smooth surface (e.g., substantially a hemispherical surface). A coil joint part <NUM> is a member that joins the core shaft <NUM> and the proximal end of the coil body <NUM> at a predetermined position between the proximal end and the distal end of the core shaft <NUM> along the axial direction.

The auxiliary wire <NUM> is arranged parallel to the distal end portion of the core shaft <NUM>. Specifically, the auxiliary wire <NUM> is a linear member that is located on the outer periphery side of the distal end portion of the core shaft <NUM> and extends along the axial direction. According to the present embodiment, when viewed from the axial direction, the auxiliary wire <NUM> is located between the distal end portion of the core shaft <NUM> and the coil body <NUM>. The distal end of the auxiliary wire <NUM> is joined to the tip <NUM>, and the rear end of the auxiliary wire <NUM> is joined to the tapered portion <NUM> of the core shaft <NUM> via a wire joint part <NUM>. The wire joint part <NUM> is formed over the entire circumference of the core shaft <NUM> (the tapered portion <NUM>). The portion from the distal end of the core shaft <NUM> to the position of the wire joint part <NUM> is an example of the distal end portion of the core shaft in claims. The relationship between the distal end portion of the core shaft <NUM> and the auxiliary wire <NUM> will be described below.

The material for forming the auxiliary wire <NUM> is, for example, metallic materials, more specifically, stainless steel (SUS302, SUS304, SUS316, etc.), piano wires, nickel-chromium based alloys, cobalt alloys, tungsten, and the like, are used. The auxiliary wire <NUM> may be made of the same material as that of the distal end portion of the core shaft <NUM>.

As the materials for forming the tip <NUM>, the coil joint part <NUM>, and the wire joint part <NUM>, known materials are used and, for example, soldering materials (aluminum alloy solder, silver solder, gold solder, etc.), metal solders (Ag-Sn alloys, Au-Sn alloys, etc.), adhesives (epoxy based adhesives, etc.), and the like, are used.

Part or all of the guide wire <NUM> may be coated with a known coating agent.

Next, the relationship between the distal end portion of the core shaft <NUM> and the auxiliary wire <NUM> in the guide wire <NUM> according to the present embodiment will be described. First, the auxiliary wire <NUM> satisfies a first requirement below.

The auxiliary wire <NUM> is more flexible than the distal end portion of the core shaft <NUM>.

The auxiliary wire <NUM> preferably satisfies a second requirement below.

The breaking strength of the auxiliary wire <NUM> is higher than the breaking strength of the distal end portion of the core shaft <NUM>.

The auxiliary wire <NUM> preferably satisfies a third requirement below.

The breaking elongation of the auxiliary wire <NUM> is shorter than the breaking elongation of the distal end portion of the core shaft <NUM>.

The auxiliary wire <NUM> preferably satisfies a fourth requirement below.

The breaking elongation of the auxiliary wire <NUM> is shorter than the elongation at a yield point P1 of the distal end portion of the core shaft <NUM>.

The auxiliary wire <NUM> preferably satisfies a fifth requirement below.

The auxiliary wire <NUM> has the configuration in which a plurality of strands is twisted together.

Here, an example of the relationship between the distal end portion of the core shaft <NUM> and the auxiliary wire <NUM> will be described. The distal end portion of the core shaft <NUM> is made of, for example, a material (such as Ni-Ti alloy) having a superelastic property. The auxiliary wire <NUM> is a wire having the configuration in which a plurality of strands, which has the outer diameter smaller than that of the distal end portion of the core shaft <NUM>, is twisted together. The strand is made of, for example, stainless steel. The outer diameter of the auxiliary wire <NUM> itself is also smaller than the outer diameter of the distal end portion (the small diameter portion <NUM>) of the core shaft <NUM>.

<FIG> is an explanatory diagram illustrating the relationship between the distal end portion of the core shaft <NUM> and the auxiliary wire <NUM>. <FIG> illustrates graphs of the relationships between the load (tensile load) and the amount of elongation in the distal end portion of the core shaft <NUM> and the auxiliary wire <NUM>, respectively. A first graph G1 is a graph of the relationship between the load and the amount of elongation in the distal end portion of the core shaft <NUM>. A second graph G2 is a graph of the relationship between the load and the amount of elongation in the auxiliary wire <NUM>.

As described above, the distal end portion of the core shaft <NUM> is made of a material having a superelastic property. Therefore, in the first graph G1, an elastic region (a region where the amount of elongation is equal to or less than LX) and a plastic region (a region where the amount of elongation is more than LX) are present in the distal end portion of the core shaft <NUM>. P1 in the first graph G1 is a yield point (also referred to as the elastic limit point) that is the boundary between the elastic region and the plastic region. In the elastic region, there are a linear elastic region and a plateau region. The linear elastic region is a region where the tensile load applied to the distal end portion of the core shaft <NUM> is substantially proportional to the amount of elongation of the distal end portion of the core shaft <NUM>. The plateau region is a region where the amount of elongation of the distal end portion of the core shaft <NUM> increases while the tensile load applied to the distal end portion of the core shaft <NUM> is substantially constant.

In the auxiliary wire <NUM>, as illustrated in the second graph G2, the amount of elongation of the auxiliary wire <NUM> increases as the tensile load applied to the auxiliary wire <NUM> increases. As described above, the auxiliary wire <NUM> has the configuration in which a plurality of strands made of stainless steel is twisted together. Therefore, the auxiliary wire <NUM> is more flexible than, for example, a stainless-steel solid wire having the same outer diameter as that of the auxiliary wire <NUM> and the distal end portion of the core shaft <NUM>.

As the auxiliary wire <NUM> has the configuration in which a plurality of strands made of stainless steel is twisted together, the breaking elongation of the auxiliary wire <NUM> is longer than the breaking elongation of a stainless-steel solid wire. Therefore, the slope of the second graph G2 is more gradual than the slope of the load and the amount of elongation (not illustrated) of a stainless-steel solid wire. More specifically, as illustrated in <FIG>, the second graph G2 intersects with the first graph G1 in the plateau region (see LY in <FIG>). This indicates the following.

As illustrated in <FIG>, the breaking strength (F2) of the auxiliary wire <NUM> is higher than the breaking strength (F <NUM>) of the distal end portion of the core shaft <NUM> (the second requirement), and the breaking elongation (L2) of the auxiliary wire <NUM> is shorter than the breaking elongation (L1) of the distal end portion of the core shaft <NUM> (the third requirement). This may prevent the breakage of the distal end portion of the core shaft <NUM> unless a tensile load exceeding the breaking strength of the auxiliary wire <NUM> is applied. The breaking elongation (L2) of the auxiliary wire <NUM> is shorter than the elongation (LX) at the yield point P <NUM> of the distal end portion of the core shaft <NUM> (the fourth requirement). This prevents the distal end portion of the core shaft <NUM> from reaching the yield point and maintains the elastic deformation state. This may prevent the occurrence of part replacement due to plastic deformation of the core shaft <NUM>.

For example, in the configuration where the breaking strength of the auxiliary wire <NUM> is more than the breaking strength of the distal end portion of the core shaft <NUM>, the auxiliary wire <NUM> is configured such that the breaking elongation (L2) of the auxiliary wire <NUM> is <NUM>% or less, preferably <NUM>% or less of the breaking elongation (L1) of the distal end portion of the core shaft <NUM>. This may prevent the core shaft <NUM> from breaking before the auxiliary wire <NUM> and may prevent the loss of operability of the guide wire <NUM> when the distal end portion of the core shaft <NUM> breaks first.

As described above, in the guide wire <NUM> according to the present embodiment, the distal end portion of the core shaft <NUM> has a pseudoelastic property. Therefore, as compared with the configuration in which, for example, the distal end portion of the core shaft <NUM> is made of a material not having a pseudoelastic property, such as stainless steel, it is possible to prevent the breakage of the core shaft <NUM> when the distal end portion is elongated due to the tensile stress applied. The auxiliary wire <NUM> is arranged parallel to the distal end portion of the core shaft <NUM>, and the auxiliary wire <NUM> is more flexible than the distal end portion of the core shaft <NUM> (the first requirement). Thus, according to the present embodiment, the auxiliary wire <NUM> may prevent the breakage of the core shaft <NUM>, while it is possible to prevent a decrease in the flexibility of the distal end portion of the core shaft <NUM> due to the presence of the auxiliary wire <NUM>.

According to the present embodiment, the breaking strength of the auxiliary wire <NUM> is higher than the breaking strength of the distal end portion of the core shaft (the second requirement). Thus, as compared with the configuration in which the breaking strength of the auxiliary wire <NUM> is equal to or less than the breaking strength of the distal end portion of the core shaft <NUM>, the breakage of the core shaft <NUM> may be prevented more effectively.

According to the present embodiment, the breaking elongation of the auxiliary wire <NUM> is shorter than the breaking elongation of the distal end portion of the core shaft <NUM> (the third requirement). Thus, as compared with the configuration in which the breaking elongation of the auxiliary wire <NUM> is equal to or more than the breaking elongation of the distal end portion of the core shaft <NUM>, the application of the tensile stress only to the core shaft <NUM> is prevented so that the breakage of the distal end portion of the core shaft <NUM> may be prevented more effectively.

According to the present embodiment, the breaking elongation of the auxiliary wire <NUM> is shorter than the elongation at the yield point P1 of the distal end portion of the core shaft <NUM> (the fourth requirement). This prevents the distal end portion of the core shaft <NUM> from reaching the yield point P <NUM> and maintains the elastic deformation state of the distal end portion of the core shaft <NUM> and, as a result, plastic deformation of the distal end portion of the core shaft <NUM> may be prevented.

According to the present embodiment, the auxiliary wire <NUM> has the configuration in which a plurality of strands is twisted together (the fifth requirement). Thus, the flexibility of the auxiliary wire <NUM> is maintained, while the breaking strength of the auxiliary wire <NUM> may be improved.

The technology disclosed in this description is not limited to the embodiment described above and may be modified to various forms and may be modified as described below for example.

The configuration of the guide wire <NUM> according to the above embodiment is merely an example and may be modified in various ways. For example, although the core shaft <NUM> includes the small diameter portion <NUM>, the tapered portion <NUM>, and the large diameter portion <NUM> according to the above-described embodiment, the core shaft <NUM> may omit at least one of the three portions or may include another portion in addition to the three portions. Specifically, the core shaft <NUM> may be configured to have substantially the same outer diameter over its entire length without the tapered portion <NUM> or may be configured such that the tapered portion <NUM> has a shape so as to extend to the distal end of the core shaft <NUM> without the small diameter portion <NUM>.

According to the above-described embodiment, the coil body <NUM> has the configuration of the tightly wound strand, but the coil body <NUM> may also have the configuration of a coarsely wound strand. The coil body <NUM> has a configuration formed in a hollow cylindrical shape by spirally winding one strand, but may also have a configuration formed in a hollow cylindrical shape by spirally winding a plurality of strands, may have a configuration formed in a hollow cylindrical shape by spirally winding one twisted wire formed by twisting a plurality of strands, or may have a configuration formed in a hollow cylindrical shape by spirally winding a plurality of twisted wires formed by twisting a plurality of strands. The guide wire <NUM> may also be configured without the coil body <NUM>.

According to the above-described embodiment, the configuration may be such that the proximal end of the auxiliary wire <NUM> is joined to the large diameter portion <NUM> of the core shaft <NUM>. The auxiliary wire <NUM> may have a configuration formed by one solid wire formed to be thin with a material having a high tensile force than the core wire, or may have a configuration formed by twisting three or more strands. The auxiliary wire <NUM> may also have a configuration that does not satisfy at least one of the second requirement to the fifth requirement described above.

The material of each member according to the above-described embodiment is merely an example and may be modified in various ways. For example, the configuration may be such that the auxiliary wire <NUM> and the distal end portion of the core shaft <NUM> are made of the same material and the outer diameter of the auxiliary wire <NUM> is smaller than the outer diameter of the distal end portion of the guide wire <NUM> so that the auxiliary wire <NUM> is more flexible than the distal end portion of the core shaft <NUM>.

Claim 1:
A guide wire (<NUM>) comprising:
a core shaft (<NUM>) including a distal end portion having a pseudoelastic property;
a tip (<NUM>) joined to a distal end of the distal end portion of the core shaft; and
an auxiliary wire (<NUM>) that is arranged parallel to the distal end portion of the core shaft, has a distal end joined to the tip, and has a rear end joined to the core shaft, wherein
the auxiliary wire is more flexible than the distal end portion of the core shaft,
a breaking strength of the auxiliary wire is higher than a breaking strength of the distal end portion of the core shaft, and characterized in that
a breaking elongation of the auxiliary wire is shorter than a breaking elongation of the distal end portion of the core shaft.