JP7596080B2 - Guidewires - Google Patents

Description

The present invention relates to a guidewire.

Conventionally, there is known a technique for attaching a marker to the tip of a medical device such as a guidewire inserted into the human body in order to identify the tip position of the device using external ultrasound or magnetic fields (Patent Documents 1 and 2). Patent Document 1 discloses a dilator with a contrast marker at its tip. Patent Document 2 discloses a catheter with a thin ferromagnetic film at its tip.

JP 2017-51328 A Japanese Patent Application Publication No. 10-314137

However, even with the above-mentioned prior art, there is still room for improvement in the technology for improving the visibility of medical devices displayed in ultrasound images and magnetic field images. For example, depending on the orientation and position of the guidewire tip inserted into the human body, a part of the guidewire tip may not appear clearly in the ultrasound image (echo image). As one example, when a guidewire whose tip is bent downward is observed from above with an ultrasound probe, the part of the guidewire beyond the bent part may be outside the detection range and not appear clearly in the echo image, and the bent part may be displayed as the tip position of the guidewire. In this case, there is a risk that the position of the bent part may be mistaken for the tip of the guidewire.

The present invention has been made to solve the above-mentioned problems, and aims to improve the visibility of the guidewire displayed in an ultrasound image.

The present invention has been made to solve at least some of the above problems, and can be realized in the following form.

(1) According to one aspect of the present invention, a guidewire is provided. The guidewire includes a core shaft, a metallic cylindrical body arranged on the outside of the core shaft, a distal tip to which the distal end of the core shaft and the distal end of the cylindrical body are fixed, and resin arranged in a range from a position a first distance away from the distal end of the cylindrical body toward the rear end to a position a second distance away, and a first section not including the resin and a second section including the resin are connected from the distal end of the guidewire toward the base end.

With this configuration, the first section, which does not include resin, and the second section, which includes resin, are connected from the tip to the base end of the guidewire, so that the positions of the first section and the second section can be easily identified in an ultrasound image. The position of the guidewire within the human body can be easily identified from the positions of the first section and the second section. Therefore, with this configuration, it is possible to improve the visibility of the guidewire displayed in an ultrasound image.

(2) In the guidewire of the above embodiment, the resin may be disposed on the outer surface of the cylindrical body in the second section. According to this configuration, the resin disposed on the outer surface of the cylindrical body makes it easier to distinguish between the first section and the second section displayed on the ultrasound image. Therefore, according to this configuration, it is possible to further improve the visibility of the guidewire displayed on the ultrasound image.

(3) In the guidewire of the above embodiment, the tubular body may include a first tubular body located in the first section and a second tubular body located in the second section. With this configuration, the difference in configuration between the first tubular body and the second tubular body makes it easier to distinguish the first section and the second section displayed on the ultrasound image.

(4) In the guidewire of the above embodiment, the outer diameter of the second cylindrical body may be smaller than the outer diameter of the first cylindrical body. With this configuration, the difference in the outer diameters of the first cylindrical body and the second cylindrical body makes it easier to distinguish the first section and the second section displayed in the ultrasound image. In addition, the difference between the outer diameter of the second section, in which resin is formed on the outside of the second cylindrical body, and the outer diameter of the first cylindrical body in the first section is reduced, thereby suppressing the occurrence of a step at the boundary between the first section and the second section.

(5) In the guidewire of the above embodiment, the resin may be disposed inside the tubular body in the second section. According to this configuration, the resin disposed inside the tubular body makes it easier to distinguish between the first section and the second section displayed in the ultrasound image. Therefore, according to this configuration, it is possible to further improve the visibility of the guidewire displayed in the ultrasound image.

(6) In the above-described guidewire, the tubular body may be a coil body. With this configuration, it is possible to improve the visibility of the guidewire displayed in an ultrasound image while ensuring the flexibility of the guidewire tip.

The present invention can be realized in various forms, such as a medical device including a guidewire, a catheter, and a method for manufacturing a guidewire.

1 is an explanatory diagram illustrating an example of an overall configuration of a guidewire according to a first embodiment; FIG. 2 is an explanatory diagram illustrating a cross-sectional configuration of the guide wire of the first embodiment. FIG. 3 is an enlarged explanatory diagram of a portion X in FIG. 2 . 1 is an explanatory diagram illustrating a difference in echo reflection intensity depending on the location of a guidewire. FIG. FIG. 13 is a diagram illustrating an example of a guidewire in a blood vessel observed by ultrasound. FIG. 13 is a diagram illustrating an example of a guidewire of a comparative example observed by ultrasound. FIG. 11 is an explanatory diagram illustrating the overall configuration of a guidewire according to a second embodiment. FIG. 11 is an explanatory diagram illustrating a cross-sectional configuration of a guide wire according to a second embodiment. 1 is a diagram illustrating an example of differences in echo reflection intensity depending on the location of a guidewire. FIG. 13 is a diagram showing a state in which the guide wire of the second embodiment is observed by ultrasound. 13 is an explanatory diagram illustrating a cross-sectional configuration of a guide wire according to a third embodiment. FIG. FIG. 13 is an explanatory diagram illustrating a cross-sectional configuration of a guide wire according to a fourth embodiment.

First Embodiment
FIG. 1 is an explanatory diagram illustrating the overall configuration of the guidewire 1 of the first embodiment. FIG. 2 is an explanatory diagram illustrating the cross-sectional configuration of the guidewire 1. FIG. 3 is an explanatory diagram in which the X portion of FIG. 2 is enlarged. Hereinafter, the left side of FIG. 1 will be referred to as the "tip side" of the guidewire 1 and each component, and the right side of FIG. 1 will be referred to as the "base side" of the guidewire 1 and each component. The tip side of the guidewire 1 is the side (distal side) that is inserted into the body, and the base side of the guidewire 1 is the side (proximal side) that is operated by a technician such as a doctor. The left-right direction of FIG. 1 is also referred to as the "extension direction" or "axial direction" of the guidewire 1 and each component. FIG. 2 shows a longitudinal section along the extension direction of the guidewire 1. The guidewire 1 is a medical instrument used, for example, when inserting a catheter into a blood vessel or a digestive organ, and comprises a core shaft 10, a first coil body 20, a second coil body 30, a distal joint portion (distal tip) 40, a base end joint portion 50, and a resin tube 60.

The core shaft 10 is a long, tapered member whose outer diameter decreases from the base end to the tip end. The core shaft 10 can be made of materials such as stainless steel alloys (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, piano wire, nickel-chromium alloys, cobalt alloys, tungsten, etc. The core shaft 10 may also be made of known materials other than those mentioned above. The core shaft 10 has, in order from the tip end to the base end, a thin diameter section 13, a tapered section 14, and a thick diameter section 15.

The thin-diameter section 13 is disposed on the tip side of the core shaft 10, and a tip joint section (tip) 40 is formed at the tip. The tapered section 14 is formed between the thin-diameter section 13 and the thick-diameter section 15, and the outer diameter becomes thinner from the base end to the tip. The thick-diameter section 15 is the maximum outer diameter section in the core shaft 10, and the outer diameter is constant from the base end of the core shaft 10 to the tip side. A base-end joint section 50 is formed on the outer periphery of the base end side, a predetermined distance away from the tip of the core shaft 10. A first coil body 20 and a second coil body 30 are disposed between the tip joint section 40 and the base-end joint section 50.

The tip joint 40 is formed of a metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, or Au-Sn alloy, and the tip of the first coil body 20 and the tip of the core shaft 10 are fixed by this metal solder. The tip joint 40 may be formed of an adhesive such as an epoxy adhesive, and the tip of the first coil body 20 and the tip of the core shaft 10 may be fixed by the adhesive. The base end joint 50 is an annular (ring-shaped) portion provided on the outer periphery of the core shaft 10, and is formed here from the same material as the tip joint 40. The base end joint 50 may be formed from a material different from that of the tip joint 40.

The first coil body 20 is a metallic cylindrical body composed of one or more coils, and is wound around the core shaft 10 so as to cover the outer periphery of the tip side of the core shaft 10. Here, the first coil body 20 is wound around the thin-diameter portion 13 of the core shaft 10. The coil constituting the first coil body 20 may be a single coil formed by spirally winding a single strand of wire with a circular cross section into a cylindrical shape, or a hollow stranded coil formed by twisting a strand of wires together into a cylindrical shape. The first coil body 20 may also be composed of a combination of a single coil and a hollow stranded coil. The first coil body 20 can be formed of, for example, stainless steel alloys (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, piano wires, nickel-chromium alloys, cobalt alloys, radiotransparent alloys such as tungsten, gold, platinum, tungsten, alloys containing these elements (for example, platinum-nickel alloys), and other radiopaque alloys. The first coil body 20 may be formed from a known metal material (including an alloy composition) other than the above. The tip of the first coil body 20 is joined to the tip of the core shaft 10 by a tip joint 40. The base end of the first coil body 20 is in contact with the tip of the second coil body 30. The base end of the first coil body 20 and the tip of the second coil body 30 may be fixed to the core shaft 10 by a fixing member (not shown). The length of the first coil body 20 can be any length, but can be in the range of 10 mm to 15 mm, for example.

The second coil body 30 is a metallic cylindrical body arranged on the base end side of the first coil body 20, and is wound around the core shaft 10 so as to cover the outer periphery of the core shaft 10. Here, the first coil body 20 is wound around the small diameter portion 13 of the core shaft 10. As shown in FIG. 3, the outer diameter (maximum outer diameter) D2 of the second coil body 30 is smaller than the outer diameter (maximum outer diameter) D1 of the first coil body 20 (D1>D2). The type and material of the coil constituting the second coil body 30 may be the same as or different from that of the first coil body 20. The base end of the second coil body 30 is joined to the core shaft 10 by a base end side joint 50.

The resin tube 60 is a cylindrical member made of resin, and covers the entire second coil body 30. The resin tube 60 is welded to the outer surface of the second coil body 30 by heating. The tip of the resin tube 60 is connected to the base end of the first coil body 20. The resin tube 60 is made of, for example, a fluororesin such as PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyalkane), silicon resin, polyurethane, polyethylene, polyvinyl chloride, polyester, polypropylene, polyamide, polystyrene, etc.

The thickness of the resin tube can be set to a value of 10% or more of the outer diameter of the cylindrical body in the second section. The thickness of the resin tube can be set to a value within a range of 10 to 40% of the outer diameter of the cylindrical body in the second section, and can be set to a value within a range of 15 to 40%. Specifically, as shown in FIG. 3, the thickness (wall thickness) T1 of the resin tube 60 can be set to a value of 10% or more of the outer diameter D2 of the second coil body 30. In order to improve the resolution of the echo image, the thickness of the resin tube can be set to a value of 30 μm or more, specifically, to a value within a range of 40 to 100 μm (for example, 50 to 90 μm), based on the sound speed and frequency of the ultrasonic waves in the resin tube. This makes it possible to more clearly distinguish the difference between the first section S1 and the second section S2 in the echo image described later. In addition, the thickness (wall thickness) T1 of the resin tube 60 can be set to a value within ±10% of the difference (1/2 of (D1-D2)) between the outer diameter D1 of the first coil body 20 and the outer diameter D2 of the second coil body 30. This can reduce the step between the first section S1 and the second section S2 described below. Note that the thickness of the resin tube (resin placed in the second section) refers to the thickness of the resin tube (resin placed in the second section) at the position where the outer diameter of the cylindrical body in the second section is maximum.

In this embodiment, the section of the guidewire 1 from the tip of the guidewire 1 to the tip of the resin tube 60 is referred to as the "first section S1," and the section from the tip of the resin tube 60 to the base end of the resin tube 60 is referred to as the "second section S2." The first section S1 is the section in which the tip joint 40 and the first coil body 20 are arranged, and can also be said to be a section from the tip of the guidewire 1 toward the base end that does not have the resin tube 60. The second section S2 is the section in which the second coil body 30 and the resin tube 60 are arranged, and can also be said to be a section connected to the first section S1 at the rear end side of the first section S1.

Figure 4 is a diagram for explaining the difference in echo reflection intensity depending on the part of the guidewire 1. Figure 4 shows a schematic diagram of the reflection of ultrasonic waves US irradiated from an ultrasonic probe (not shown) at the first section S1 and the second section S2 of the guidewire 1. The ultrasonic waves US irradiated to the first section S1 of the guidewire 1 are reflected, for example, at the outer surface of the first coil body 20, and a reflected wave RW is generated from each part. Since the first coil body 20 in the first section S1 is not covered with the resin tube 60, the change in acoustic impedance at the outer surface of the first coil body 20 (the difference between the acoustic impedance of the first coil body 20 and the acoustic impedance of the medium (e.g. blood) in contact with the outer surface of the first coil body 20) is relatively large, and the reflected wave RW becomes relatively strong (the echo reflection intensity becomes high).

The ultrasound US irradiated to the second section S2 of the guidewire 1 is reflected by the outer surface of the second coil body 30, as in the first section S1, and a reflected wave RW is generated from each part. Since the outer surface of the second coil body 30 is covered with the resin tube 60, the change in acoustic impedance (the difference between the acoustic impedance of the first coil body 20 and the acoustic impedance of the resin tube 60) on the outer surface of the second coil body 30 is relatively small, and the reflected wave RW is relatively weak (the echo reflection intensity is low).

In the coil bodies 20 and 30 in FIG. 4, each wire is densely wound. For example, in the coil body 20, the wire is spirally wound (densely wound) so that adjacent wire portions in FIG. 4 come into contact. Similarly, in the coil body 30, the wire is spirally wound (densely wound) so that adjacent wire portions in FIG. 4 come into contact. In addition, each wire in each of the coils can be loosely wound. For example, in each coil, the wire may be spirally wound (sparsely wound) so that adjacent wire portions in FIG. 4 do not come into contact (so that gaps are created). In this case, ultrasonic waves are transmitted to the inside of each coil body through the gaps between adjacent wires of each coil body, and reflected waves are generated inside each coil body. The reflection of ultrasonic waves inside the coil body will be described later with reference to FIG. 9.

Figure 5 is an explanatory diagram illustrating an example of the state observed by ultrasonic echo with the guidewire 1 placed in the blood vessel BV. Figure 5 (A) is an explanatory diagram illustrating the guidewire 1 in a straight line in the blood vessel BV and the ultrasonic probe (probe) 90. Figure 5 (B) is an explanatory diagram illustrating the guidewire 1 bent downward in the blood vessel BV and the ultrasonic probe 90. Figure 5 (C) is an ultrasonic image (echo image) EI generated by ultrasonic echo from the ultrasonic probe 90 when the guidewire 1 is in the state of Figure 5 (A). Figure 5 (D) is an echo image EI generated by ultrasonic echo from the ultrasonic probe 90 when the guidewire 1 is in the state of Figure 5 (B).

As shown in FIG. 4, the guidewire 1 of this embodiment has different echo reflection intensities in the first section S1 and the second section S2. Therefore, as shown in FIG. 5(C) and FIG. 5(D), in the echo image EI, the guidewire image GWI representing the guidewire 1 has a relatively bright portion corresponding to the first section S1 and a relatively dark portion corresponding to the second section S2. The positions of the first section S1 and the second section S2 can be identified based on the difference in brightness between the portion corresponding to the first section S1 and the portion corresponding to the second section S2, and the tip position of the guidewire 1 can be easily estimated from the position. Conventionally, when the tip of the guidewire is bent downward, the tip of the guidewire falls out of the detection range of the ultrasonic probe (probe), and the bent position is displayed as the tip position of the guidewire in the echo image. However, according to the guidewire 1 of this embodiment, when the tip of the guidewire 1 is bent downward as shown in FIG. 5(B), the portion corresponding to the first section S1 is displayed relatively shorter than the portion corresponding to the second section S2 as shown in FIG. 5(D). This makes it possible to prevent the bending position of the guidewire 1 from being mistaken for the tip position. In addition, the surgeon can recognize that the guidewire 1 is bent downward from the shortness of the first section S1 in FIG. 5(D). In this way, the state of the guidewire 1 can be easily recognized from the respective states of the first section S1 and the second section S2 displayed in the echo image EI.

In the above explanation, it has been explained that the state of the guidewire can be identified based on the brightness of the echo images of the first section S1 and the second section S2. In addition, in the second section S2, reflected waves are generated on the outer peripheral surface of the resin tube and on the inner peripheral surface, or ultrasonic waves are attenuated within the resin tube. When the ultrasound probe receives these reflected waves, differences occur between the echo image of the second section S2 and the echo image of the first section S1, for example, the echo image of the second section S2 appears double. Based on such differences, the state of the guidewire 1 can also be recognized.

Figure 6 is an explanatory diagram illustrating the appearance of the guidewire 1A of the comparative example when placed in a blood vessel BV and observed by ultrasonic echo. Figures 6(A) to 6(D) correspond to Figures 5(A) to 5(D), respectively. In the guidewire 1A of the comparative example, the coil body at the tip is not covered with a resin tube. In other words, the guidewire 1A of the comparative example has only a first section S1A having a configuration similar to that of the first section S1 of the first embodiment, and has no portion corresponding to the second section S2 of the first embodiment.

The guidewire 1A of the comparative example has a constant echo reflection intensity from the tip to the base of the first section S1A. In addition, the echo reflection intensity of the first section S1A and the core shaft portion proximal to the first section S1A is also almost constant. Therefore, as shown in Fig. 6(C) and Fig. 6(D), in the guidewire image GWI representing the guidewire 1A, the portion corresponding to the first section S1A and the portion proximal to the first section S1A are displayed with the same brightness, making them difficult to distinguish. Therefore, the echo image EI is displayed in the same way when the tip of the guidewire 1A is straight as in Fig. 6(A) and when the tip of the guidewire 1A is bent downward as in Fig. 6(B) (Figs. 6(C) and 6(D)). As a result, in Fig. 6(D), there was a risk of mistaking the bending position of the guidewire 1A for the tip position of the guidewire 1A.

On the other hand, according to the guidewire 1 of this embodiment, the first section S1 not including the resin tube 60 and the second section S2 including the resin tube 60 are connected to each other, so that the positions of the first section S1 and the second section S2 can be easily identified in the guidewire image GWI of the ultrasound image (echo image) EI, as shown in FIG. 5(C) and FIG. 5(D). Therefore, it is possible to easily grasp the state of the tip position of the guidewire 1 displayed in the echo image EI (improving visibility). In addition, as shown in FIG. 4, since the resin tube 60 is disposed on the outer surface of the second coil body 30, it is possible to reduce the echo reflection intensity on the outer surface of the second coil body 30. This makes it possible to more clearly distinguish the difference between the first section S1 and the second section S2 displayed in the echo image EI.

According to the guidewire 1 of this embodiment, since the outer diameter D2 of the second coil body 30 is smaller than the outer diameter D1 of the first coil body 20, the portion corresponding to the second coil body 30 in the echo image EI is smaller and less noticeable than the portion corresponding to the first coil body 20, and the difference between the first section S1 and the second section S2 can be made larger (clearer). Also, since the outer diameter D2 of the second coil body 30 is smaller than the outer diameter D1 of the first coil body 20, even if a resin tube 60 is placed outside the second coil body 30, the difference between the outer diameter (D2 + (T1 × 2)) of the second section S2 and the outer diameter (D1) of the first section S1 can be reduced, and the occurrence of a step at the boundary between the first section S1 and the second section S2 can be suppressed.

According to the guidewire 1 of this embodiment, the coil body (first coil body 20 and second coil body 30) is used as a marker for identifying the tip of the guidewire in the echo image EI. Therefore, the coil body can improve the visibility of the guidewire displayed in the echo image while ensuring the flexibility of the tip of the guidewire.

Second Embodiment
Fig. 7 is an explanatory diagram illustrating an overall configuration of a guidewire 1B of a second embodiment. Fig. 8 is an explanatory diagram illustrating a cross-sectional configuration of the guidewire 1B. The guidewire 1B of the second embodiment is different from the guidewire 1 of the first embodiment (Fig. 2) mainly in that a resin tube 80 corresponding to the resin tube 60 of the first embodiment is disposed inside the coil body, a single coil body 20b is disposed instead of the two coil bodies (first coil body 20 and second coil body 30) of the first embodiment, and the wire of the coil body 20b is wound in a spiral shape (sparsely wound) so that adjacent wire portions do not contact each other (so as to generate a gap) in Fig. 9.

The guidewire 1B includes a core shaft 10, a coil body 20b, a distal joint (distal tip) 40, a proximal joint 50, a resin tube 80, and a resin coating 70. The core shaft 10, the distal joint 40, and the proximal joint 50 are the same as those in the first embodiment, and therefore will not be described. The coil body 20b differs from the first coil body 20 in the first embodiment only in length, and is otherwise the same. The distal end of the coil body 20b in the second embodiment is joined to the distal end of the core shaft 10 by the distal joint 40. The proximal end of the coil body 20b is joined to the core shaft 10 by the proximal joint 50.

The resin tube 80 is a cylindrical member made of resin, and covers the core shaft 10 inside the coil body 20b. The resin tube 80 is welded to the inner surface of the coil body 20b and the outer surface of the core shaft 10 by heating. The length of the resin tube 80 is shorter than the length of the coil body 20b, and is disposed only on the rear end side of the coil body 20b inside the coil body 20b. The base end of the resin tube 80 is connected to the base end joint 50 in the same manner as the base end of the coil body 20b. The resin tube 80 is made of the same material as the resin tube 60 of the first embodiment.

The resin coating 70 is a thin layer of a resin having optical transparency that covers the outer surface of the coil body 20b. The resin coating 70 is a transparent coating here, and covers the entire guide wire 1B. The resin coating 70 may be made of a fluororesin such as PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyalkane), a silicone resin, polyurethane, polyethylene, polyvinyl chloride, polyester, polypropylene, polyamide, polystyrene, or the like. The outer surface of the resin coating 70 may be flat, or may have irregularities formed along the extension direction.

In the guidewire 1B, the section from the tip of the guidewire 1B to the tip of the resin tube 80 is called the "first section S1B," and the section from the tip of the resin tube 80 to the base end of the resin tube 80 is called the "second section S2B." The first section S1B is the section in which the tip joint 40 and the tip side of the coil body 20b are arranged, and can also be said to be a section that does not have the resin tube 80 from the tip to the base end side of the guidewire 1B. The second section S2B is the section in which the rear end side of the coil body 20b and the resin tube 80 are arranged, and can also be said to be a section connected to the first section S1B at the rear end side of the first section S1B.

9 is a diagram for explaining the difference in echo reflection intensity depending on the part of the guidewire 1B. FIG. 9 corresponds to FIG. 4 of the first embodiment, and shows a schematic diagram of the ultrasonic wave US irradiated from an ultrasonic probe (not shown) being reflected in the first section S1B and the second section S2B of the guidewire 1B. The ultrasonic wave US irradiated to the first section S1B of the guidewire 1B is reflected, for example, on the outer surface and inner surface of the coil body 20b, the outer surface of the core shaft 10, etc., and a reflected wave RW is generated from each part. Since the resin tube 80 is not arranged inside the coil body 20b in the first section S1B, the change in acoustic impedance (the difference in acoustic impedance between the coil body 20b and the medium (e.g., blood) in contact with the coil body 20b, and the difference in acoustic impedance between the core shaft 10 and the medium in contact with the core shaft 10) on the inner surface of the coil body 20b and the outer surface of the core shaft 10 is relatively large, and the reflected wave RW becomes relatively strong (the echo reflection intensity becomes high).

The ultrasound US irradiated to the second section S2B of the guidewire 1B is reflected by the outer and inner surfaces of the coil body 20b, the outer surface of the core shaft 10, etc., in the same manner as in the first section S1B, and a reflected wave RW is generated from each of these locations. Since the resin tube 80 is disposed inside the coil body 20b in the second section S2B, the change in acoustic impedance (difference in acoustic impedance between the coil body 20b and the resin tube 80, and difference in acoustic impedance between the core shaft 10 and the resin tube 80) on the inner surface of the coil body 20b and the outer surface of the core shaft 10 is relatively small, and the reflected wave RW is relatively weak (low echo reflection intensity).

In this way, by using a loosely wound coil body 20b, reflected waves RW are generated inside the coil body 20b as well, resulting in a difference in the strength of the reflected waves between the first and second sections.

Figure 10 is an explanatory diagram illustrating the state of the guidewire 1B of the second embodiment observed by ultrasonic echo when placed in the blood vessel BV. Figure 10 corresponds to Figure 5 of the first embodiment. Figure 10 (A) is an explanatory diagram illustrating the guidewire 1B straight in the blood vessel BV and the ultrasonic probe (probe) 90. Figure 10 (B) is an explanatory diagram illustrating the guidewire 1B bent downward in the blood vessel BV and the ultrasonic probe 90. Figure 10 (C) is an ultrasonic image (echo image) EI generated by ultrasonic echo by the ultrasonic probe 90 when the guidewire 1B is in the state of Figure 10 (A). Figure 10 (D) is an echo image EI generated by ultrasonic echo by the ultrasonic probe 90 when the guidewire 1B is in the state of Figure 10 (B).

As shown in FIG. 9, the first section S1B and the second section S2B of the guidewire 1B have different echo reflection intensities. Therefore, as shown in FIG. 10(C) and FIG. 10(D), the guidewire image GWI representing the guidewire 1B has a relatively bright portion corresponding to the first section S1B and a relatively dark portion corresponding to the second section S2B. Due to the difference in brightness between the portion corresponding to the first section S1B and the portion corresponding to the second section S2B, the positions of the first section S1B and the second section S2B can be identified, and the tip position of the guidewire 1B can be easily estimated from the position. According to the guidewire 1B, when the tip of the guidewire 1B is bent downward as shown in FIG. 10(B), the portion corresponding to the first section S1B is displayed relatively shorter than the portion corresponding to the second section S2B as shown in FIG. 10(D). This makes it possible to suppress the misidentification of the bent position of the guidewire 1B as the tip position. In addition, the surgeon can recognize that the guidewire 1B is bent downward from the shortness of the portion corresponding to the first section S1B in FIG. 10(D). In this way, the state of the guidewire 1B can be easily recognized from the respective states of the first section S1B and the second section S2B displayed in the echo image EI.

As described above, even if the resin tube 80 is disposed inside the coil body 20b as in the guidewire 1B of the second embodiment, the visibility of the guidewire in the echo image can be improved. That is, even in the guidewire 1B of the second embodiment, the first section S1B not including the resin tube 80 and the second section S2B including the resin tube 80 are connected to each other, so that the positions of the first section S1B and the second section S2B can be easily identified in the guidewire image GWI of the ultrasound image (echo image) EI, as shown in FIG. 10(C) and FIG. 10(D). Therefore, it is possible to easily grasp the state of the tip position of the guidewire 1B displayed in the echo image EI (improving visibility).

Third Embodiment
Fig. 11 is an explanatory diagram illustrating a cross-sectional configuration of a guidewire 1C of the third embodiment. The guidewire 1C of the third embodiment is different from the guidewire 1 of the first embodiment (Fig. 2) mainly in that a single coil body 20c is arranged instead of the two coil bodies (first coil body 20 and second coil body 30) of the first embodiment, and that a resin coating 70 is formed on the surfaces of the coil body 20c and a resin tube 60c.

The guidewire 1C includes a core shaft 10, a coil body 20c, a tip joint 40, a base joint 50, a resin tube 60c, and a resin coating 70. The core shaft 10, tip joint 40, base joint 50, and resin coating 70 are similar to those in the first and second embodiments, and therefore will not be described. The coil body 20c differs from the second coil body 30 of the first embodiment only in length, and is otherwise similar. The tip of the coil body 20c of the third embodiment is joined to the tip joint 40, and the base end is joined to the base joint 50.

The resin tube 60c is a cylindrical member made of resin, covers the base end side of the coil body 20c, and is welded to the outer surface of the base end side of the second coil body 30 by heating. The length of the resin tube 60c is shorter than that of the coil body 20c, and covers only the base end side of the coil body 20c, not the tip side of the coil body 20c. The resin tube 60c is made of the same material as the resin tube 60 of the first embodiment.

In the guidewire 1C, the section from the tip of the guidewire 1C to the tip of the resin tube 60c is called the "first section S1C", and the section from the tip of the resin tube 60c to the base end of the resin tube 60c is called the "second section S2C". The first section S1C does not include the resin tube 60c from the tip to the base end side of the guidewire 1C. The second section S2C includes the resin tube 60c and is connected to the first section S1C at the rear end side of the first section S1C. The first section S1C and the second section S2C of the guidewire 1C have different echo reflection intensities. Therefore, in the echo image, a relatively bright part corresponding to the first section S1C and a relatively dark part corresponding to the second section S2C are generated. The positions of the first section S1C and the second section S2C can be identified based on the difference in brightness between the part corresponding to the first section S1C and the part corresponding to the second section S2C, and the tip position of the guidewire 1C can be easily estimated from this.

As explained above, even if the coil at the tip is composed of a single coil body 20c, as in the guidewire 1C of the third embodiment, the visibility of the guidewire displayed in the echo image can be improved. Note that the guidewire 1 of the first embodiment is more preferable because it can reduce the step caused by the resin tube due to the difference in outer diameter between the two coil bodies.

Fourth Embodiment
12 is an explanatory diagram illustrating a cross-sectional configuration of a guidewire 1D of the fourth embodiment. The guidewire 1D of the fourth embodiment is mainly different from the guidewire 1 of the first embodiment (FIG. 2) in that a resin tube 80d corresponding to the resin tube 60 of the first embodiment is disposed inside the coil body, and that a single coil body 20d is disposed instead of the two coil bodies (first coil body 20 and second coil body 30) of the first embodiment. The guidewire 1D of the fourth embodiment is mainly different from the guidewire 1B of the second embodiment (FIG. 8) in that the resin tube 80d is not in contact with the inner surface of the coil body 20d, the base end of the resin tube 80d is not in contact with the base end side joint portion 50, and the coil body 20d is densely wound. The coil body 20d may be loosely wound.

The guidewire 1D includes a core shaft 10, a coil body 20d, a tip joint 40, a base joint 50, a resin tube 80d, and a resin coating 70. The core shaft 10, the coil body 20d, the tip joint 40, the base joint 50, and the resin coating 70 are the same as those in the second embodiment, and therefore will not be described. The resin tube 80d is a cylindrical member formed of resin, and covers the core shaft 10 inside the coil body 20d. The outer diameter of the resin tube 80 is smaller than the inner diameter of the coil body 20d, and there is a gap between the outer surface of the resin tube 80 and the inner surface of the coil body 20d. The length of the resin tube 80d is shorter than the length of the coil body 20d, and the resin tube 80d is disposed near the center of the coil body 20d inside the coil body 20d, and has a predetermined distance between the tip and rear ends of the coil body 20d. The resin tube 80d is made of the same material as the resin tube 60 of the first embodiment.

In the guidewire 1D, the section from the tip of the guidewire 1D to the tip of the resin tube 80d is called the "first section S1D", and the section from the tip of the resin tube 80d to the base end of the resin tube 80d is called the "second section S2D". In this case, the first section S1D does not include the resin tube 80d from the tip of the guidewire 1D toward the base end. The second section S2D includes the resin tube 80d and is connected to the first section S1D at the rear end side of the first section S1D. In the guidewire 1D, the echo reflection intensity of the first section S1D and the second section S2D are different. Therefore, in the echo image, a relatively bright part corresponding to the first section S1D and a relatively dark part corresponding to the second section S2D are generated. The positions of the first section S1D and the second section S2D can be identified based on the difference in brightness between the portion corresponding to the first section S1D and the portion corresponding to the second section S2D, and from this the tip position of the guidewire 1D can be easily estimated.

As described above, even if the base end of the resin tube 80d arranged inside the coil body 20d is located closer to the tip side than the base end of the coil body 20d, as in the guidewire 1D of the fourth embodiment, the visibility of the tip of the guidewire in the echo image can be improved. Also, even if the outer surface of the resin tube 80d is not in contact with the inner surface of the coil body 20d, the visibility of the guidewire displayed in the echo image can be improved.

<Modifications of this embodiment>
The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

[Modification 1]
In the guidewire 1 (FIG. 2) of the first embodiment, a resin coating 70 (FIG. 8) may be formed on the outer surfaces of the first coil body 20 and the resin tube 60. Even in this case, if the acoustic impedance of the resin coating 70 is different from that of the resin tube 60, the visibility of the guidewire 1 displayed in the echo image can be improved. For example, when the acoustic impedance of the resin coating 70 is smaller than that of the resin tube 60, the change in acoustic impedance (the difference between the acoustic impedance of the first coil body 20 and the acoustic impedance of the resin coating 70) on the outer surface of the first coil body 20 is relatively large, and the reflected wave RW becomes relatively strong (the echo reflection intensity becomes high). On the other hand, the change in acoustic impedance (the difference between the acoustic impedance of the first coil body 20 and the acoustic impedance of the resin tube 60) on the outer surface of the second coil body 30 is relatively small, and the reflected wave RW becomes relatively weak (the echo reflection intensity becomes low). As a result, a difference in brightness occurs between the part corresponding to the first section S1 and the part corresponding to the second section S2 in the echo image. From this, the tip position of the guide wire 1 can be easily estimated.

[Modification 2]
In the guidewire 1 ( FIG. 2 ) of the first embodiment, the base end of the resin tube 60 may be located closer to the distal end than the base end of the second coil body 30 and may not be in contact with the base-end joint portion 50. Alternatively, the base end of the resin tube 60 may be located closer to the proximal end than the base end of the second coil body 30 and may cover the base-end joint portion 50 and the tapered portion 14.

[Modification 3]
In the guidewire 1 (FIG. 2) of the first embodiment, a single coil having different outer diameters at the distal end and proximal end may be used instead of the first coil body 20 and the second coil body 30. Also, at least one of the first coil body 20 and the second coil body 30 may be composed of two or more coil bodies. Also, in the guidewire 1 (FIG. 2) of the first embodiment, a metal tube may be used instead of the first coil body 20 and the second coil body 30. Similarly, in the second to fourth embodiments, a metal tube may be used instead of the coil bodies.

[Modification 4]
The resin tubes 60, 80, 60c, and 80d in the first to fourth embodiments may be formed of a plurality of types of resin. Also, the resin tubes 60, 80, 60c, and 80d may be composed of a plurality of tubes. Also, in the first to fourth embodiments, a resin that is not tubular may be used instead of the resin tubes 60, 80, 60c, and 80d. In this case, the resin does not have to have a ring-shaped cross section.

[Modification 5]
The configurations of the guidewires of the first to fourth embodiments may be combined as appropriate. For example, the configuration of the resin tube 80d (FIG. 12) of the fourth embodiment may be combined with the resin tube 80 of the second embodiment (FIG. 8) so that the outer surface of the resin tube 80 of the second embodiment does not come into contact with the inner surface of the coil body 20b. Alternatively, the base end of the resin tube 80 of the second embodiment may not come into contact with the base end side joint portion 50. Also, the configuration of the resin tube 80 of the second embodiment may be combined with the guidewire 1 of the first embodiment (FIG. 2) so that the resin tube is disposed both inside and outside the coil body in the guidewire 1 of the first embodiment. The coil bodies of the first to fourth embodiments may be densely wound or loosely wound as a whole. Also, a part may be loosely wound and the remaining part may be densely wound.

Although this aspect has been described above based on the embodiment and modified examples, the embodiment of the above-mentioned aspect is intended to facilitate understanding of this aspect and does not limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

Reference Signs List 1, 1A to 1D: guide wire 10: core shaft 13: thin diameter section 14: tapered section 15: thick diameter section 20: first coil body 20b to 20d: coil body 30: second coil body 40: tip joint section 50: base end joint section 60, 60c, 80, 80d: resin tube 70: resin coating 90: ultrasonic probe BV: blood vessel EI: echo image US: ultrasound RW: reflected wave GWI: guide wire image

Claims (4)

A guidewire comprising:
A core shaft;
a metallic cylindrical body disposed on the outside of the core shaft;
a tip tip to which the tip of the core shaft and the tip of the cylindrical body are fixed;
a resin disposed in a range from a position a first distance away from the front end of the cylindrical body toward the rear end to a position a second distance away,
a first section not including the resin and a second section including the resin are connected to each other from the distal end to the proximal end of the guidewire;
The resin is disposed on an outer surface of the cylindrical body in the second section,
The cylindrical body is not disposed on the outer surface of the resin,
The cylindrical body is a coil body, and in the second section, the coil body is tightly wound such that adjacent wires are in contact with each other.
Guidewire. 2. The guidewire of claim 1,
the cylindrical body includes a first coil body located in the first section and a second coil body located in the second section,
The first coil body and the second coil body are in contact with each other.
Guidewire. 2. The guidewire of claim 1,
The thickness of the resin is 10 to 40% of the outer diameter of the coil body located in the second section. 3. The guidewire of claim 2,
The outer diameter of the second coil body is smaller than the outer diameter of the first cylindrical coil body .

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