Patent Publication Number: US-2020282185-A1

Title: Guidewire

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a Continuation of PCT/JP2018/003327 filed Feb. 1, 2018. The disclosure of the prior application is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     The disclosed embodiments relate to a medical device. In particular, the disclosed embodiments relate to a guidewire. 
     Conventionally, a variety of guidewires for guiding a catheter or the like that are used by being inserted into tubular organs such as a blood vessel, a gastrointestinal tract and a ureter or body tissues for treatment or examination have been developed. For example, Japanese Patent Application Publication No. 2004-41254 A discloses a guidewire comprising a contrast portion at a distal portion of a core member, and a synthetic resin coating layer on an outer periphery of the core member and the contrast portion (see  FIG. 1  etc.). Further, a lubricious coating agent is applied to a surface of the synthetic resin coating layer described in Japanese Patent Application Publication No. 2004-41254 A. 
     As the guidewire described in Japanese Patent Application Publication No. 2004-41254 A includes a coil body being the contrast portion at the distal portion of the core member, and includes the synthetic resin coating layer on the outer periphery of the coil body, there is a problem that flexibility of a distal portion of the guidewire is impaired. 
     The synthetic resin coating layer and a lubricious coating agent formed on the surface of the synthetic resin coating layer (hereinafter, a synthetic resin coating layer and a lubricious coating agent are collectively referred to as “coating agent”) are likely to be peeled from the core member in the guidewire described in Japanese Patent Application Publication No. 2004-41254 A. Although the possibility of delamination has been slightly improved by the anchor effect due to an outer diameter of the contrast portion being larger than an outer diameter of the core member (hereinafter, referred to as “core shaft”), it was not sufficient yet. 
     The disclosed embodiments have been devised in response to the forgoing problems of the conventional technique and include a guidewire capable of ensuring flexibility of a distal portion of the guidewire and preventing the coating agent from peeling from the core shaft. 
     SUMMARY 
     To address the foregoing problems, a guidewire according to the disclosed embodiments comprises a core shaft, a coil body having a distal end that is joined to the core shaft at a position spaced proximally from a distal end of the core shaft, and a coating agent covering an outer periphery of the core shaft and the coil body, wherein the core shaft includes a bulge portion joined at a position spaced distally from the distal end of the coil body, the coating agent covers the core shaft and the coil body from a distal side of a distal end of the bulge portion to a proximal side of a proximal end of the core shaft except for an interior of the coil body. 
     A guidewire of the disclosed embodiments can comprise a stranded wire joined to a distal portion of the core shaft, including a plurality of wires and extending distally from the distal end of the core shaft, wherein the coil body extends distal to the distal end of the core shaft and along the stranded wire, the coating agent covers an outer periphery of the stranded wire, the core shaft and the coil body, the bulge portion is joined to the stranded wire at a position spaced distally from a distal end of the coil body, and the coating agent covers the stranded wire, the core shaft and the coil body from the distal side of the distal end of the bulge portion to the proximal side of the proximal end of the core shaft except for the interior of the coil body. 
     The coating agent can penetrate between a plurality of wires included in the stranded wire. 
     According to the guidewire of the disclosed embodiments, as a guidewire comprises a core shaft, a coil body having a distal end that is joined to the core shaft at a position spaced proximally from a distal end of the core shaft, and a coating agent covering an outer periphery of the core shaft and the coil body, wherein the core shaft includes a bulge portion joined at a position spaced distally from the distal end of the coil body, and the coating agent covers the core shaft and the coil body from a distal side of a distal end of the bulge portion to a proximal side of a proximal end of the core shaft except for an interior of the coil body, it is possible to ensure flexibility of the coil body and a distal portion of the guidewire and prevent the coating agent from peeling from the core shaft and the coil body by the bulge portion and the coil body. 
     Further, when the guidewire comprises a stranded wire joined to a distal portion of the core shaft, including a plurality of wires and extending distally from the distal end of the core shaft, and wherein the coil body extends distal to the distal end of the core shaft and along the stranded wire, the coating agent covers an outer periphery of the stranded wire, the core shaft and the coil body, the bulge portion is joined to the stranded wire at a position spaced distally from a distal end of the coil body, and the coating agent covers the stranded wire, the core shaft and the coil body from the distal side of the distal end of the bulge portion to the proximal side of the proximal end of the coil body except for the interior of the coil body, it is possible to ensure more flexibility of the coil body, the stranded wire and a distal portion of the guidewire and further prevent the coating agent from peeling from the core shaft, the stranded wire and the coil body by the bulge portion and the coil body. 
     Furthermore, when the coating agent penetrates between a plurality of wires included in the stranded wire, it is possible to further prevent the coating agent from peeling from the stranded wire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a guidewire of the disclosed embodiments. 
         FIG. 2  is a longitudinal sectional view of the guidewire of  FIG. 1 . 
         FIG. 3  is a schematic diagram of a guidewire of the disclosed embodiments. 
         FIG. 4  is a longitudinal sectional view of the guidewire of  FIG. 3 . 
         FIG. 5  is a longitudinal sectional view of a distal portion of a guidewire of the disclosed embodiments. 
         FIG. 6  is a longitudinal sectional view near a stranded wire included in the guidewire of  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. 
       FIG. 1  is a schematic view of a guidewire of the disclosed embodiments, and  FIG. 2  is a longitudinal sectional view of the guidewire of  FIG. 1 . 
     As shown in  FIG. 1 , a guidewire  1  of the disclosed embodiments includes a core shaft  3 , a coil body  5  joined to the core shaft  3  at a position spaced proximally from a distal end of the core shaft  3 , a bulge portion  9  joined to the core shaft  3  at a position spaced distally from a distal end of the coil body  5 , and a coating agent (coating layer)  7  covering an outer periphery of the core shaft  3 , the coil body  5  and the bulge portion  9 . 
     The core shaft  3  is a rod-like member of circular cross-section, which is reduced in diameter toward a distal end from a proximal end of the core shaft  3 , and is an elongate flexible member. Material of the core shaft  3  is not particularly limited as long as it is a biocompatible material such as stainless steel, Ni—Ti-based alloys, cobalt based alloys or the like. 
     The coil body  5  is joined to the core shaft at a position spaced proximally from a distal end of the core shaft  3 . Specifically, a distal end of the coil body  5  is joined to the core shaft  3  by a brazing material  2 , and a proximal end of the coil body  5  is joined to the core shaft  3  by a brazing material  4 . 
     Incidentally, the brazing material  2  and the brazing material  4  are not particularly limited as long as they are each a biocompatible brazing material such as gold-tin brazing material, silver-tin brazing material or the like. The coil body  5  is a cylindrical hollow coil which is formed by winding a single metal wire or a plurality of metal wires. An outer diameter of the coil body  5  is larger than an outer diameter of the core shaft  3  in the position in which the coil body  5  is joined. 
     Material of the metal wire forming the coil body  5  is not particularly limited as long as it is a biocompatible material such as stainless steel, tungsten, Ni—Ti-based alloys or the like. 
     The bulge portion  9  is joined to the distal end of the core shaft  3  at a position spaced distally from the distal end of the coil body  5 . An outer diameter of the bulge portion  9  is greater than an outer diameter of the core shaft  3  at a position at which the bulge portion  9  is joined to the core shaft  3 . Material used for the bulge portion  9  is generally a brazing material similar to the brazing material  2  and the brazing material  4  joining the coil body  5  to the core shaft  3 . 
     An area of the coating agent  7  is illustrated by hatching in  FIG. 2 . As shown in  FIG. 2 , the coating agent  7  covers the core shaft  3 , the coil body  5  and the bulge portion  9  from a distal end of the guidewire  1  (which is at a distal side of the distal end of the bulge portion  9 ) to the proximal side of the proximal end of the coil body  5  except for the interior of the coil body  5 . 
     It is to ensure the flexibility of the distal end of the guidewire  1  not to allow the coating agent  7  to penetrate inside the coil body  5 . 
     The coating agent  7  can cover the core shaft  3  all the way to the proximal end of the core shaft  3  on a proximal side of the proximal end of the coil body  5  in order to reduce frictional resistance of the guidewire  1 . 
     The coating agent  7  is preferably formed by low friction material, e.g. polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polyacrylamide, polyacrylic acid, sodium polyacrylate, poly (2-hydroxyethyl methacrylate), maleic anhydride copolymer, ethylene-vinyl alcohol copolymer, 2-methacryloyloxyethyl phosphorylcholine or a copolymer thereof, (2-hydroxyethyl methacrylate)-styrene block copolymer, various synthetic polypeptides, collagen, hyaluronic acid, cellulose-based polymer, and mixtures thereof. 
     Further, the coating agent  7  may be made of different materials depending on a position of the guidewire  1 . For example, material of a distal side region from a middle position of the coil body  5  may be a coating agent  7  made of different materials from material of a proximal side region therefrom. 
     Because the guidewire  1  comprises a core shaft  3 , a coil body  5  having a distal end that is joined to the core shaft  3  at a position spaced proximally from a distal end of the core shaft  3 , and a coating agent  7  covering an outer periphery of the core shaft  3  and the coil body  5 , wherein the core shaft  3  includes a bulge portion  9  joined at a position spaced distally from the distal end of the coil body  5 , and the coating agent  7  covers the core shaft  3  and the coil body  5  from a distal side of a distal end of the bulge portion  9  to a proximal side of a proximal end of the coil body  5  except for an interior of the coil body  5 , it is possible to ensure flexibility of the coil body  5  and a distal portion of the guidewire  1  and prevent the coating agent  7  from peeling from the core shaft  3  and the coil body  5  by the bulge portion  9  and the coil body  5 . 
     The bulge portion  9  may be joined to the distal end of the core shaft  3  so that the distal end of the core shaft  3  does not protrude from the bulge portion  9 . According to this configuration, it is possible to prevent the distal end of the core shaft  3  from protruding from the coating agent  7  and damaging to the body tissue. 
       FIG. 3  is a schematic diagram of a guidewire of the disclosed embodiments, and  FIG. 4  is a longitudinal sectional view of the guidewire of  FIG. 3 . 
     As shown in  FIG. 3 , a guidewire  10  of the disclosed embodiments includes a core shaft  13 , a stranded wire  16  joined to a distal portion of the core shaft  13  so as to be located on a distal side of the core shaft  13  and including a plurality of wires, a coil body  15  extending distal to a distal end of the core shaft  13  and having a distal end joined to the stranded wire  16  at a position spaced proximally from a distal end of the stranded wire  16  and a proximal end joined to the core shaft  13 , a coating agent  17  covering an outer periphery of the core shaft  13 , the stranded wire  16  and the coil body  15 , and a bulge portion  19  joined to the stranded wire  16  at a position spaced distally from a distal end of the coil body  5 . 
     The core shaft  13  is a rod-like member of circular cross-section, which is reduced in diameter toward a distal end from a proximal end of the core shaft  13 , and is an elongate flexible member similar to the core shaft  3 . Material of the core shaft  13  is the same as that of the core shaft  3 . 
     As shown in  FIG. 4 , the stranded wire  16  includes a proximal end joined to a distal portion of the core shaft  13  by a brazing material  18  inside the coil body  15 , and extends distal to a distal end of the core shaft  13  and a distal end of the coil body  15 . For example, the proximal end of the stranded wire  16  may be joined to the core shaft  13  at a position approximately halfway along the longitudinal length of the coil body  15 . 
     Incidentally, the stranded wire  16  may be joined to both the coil body  15  and the core shaft  13  by the brazing material  18 . 
     The coil body  15  includes a distal end joined to the stranded wire  16  and a proximal end joined to the core shaft  13 . Specifically, the distal end of the coil body  15  is joined to the stranded wire  16  by a brazing material  12 , and the proximal end of the coil body  15  is joined to the core shaft  13  by a brazing material  14 . 
     Incidentally, the brazing material  12 , the brazing material  14  and the brazing material  18  may use a material similar to that of the brazing material  2  and the brazing material  4  of the guidewire  1 . Also, the coil body  15  is similar to the coil body  5  of the guidewire  1 , and thus an outer diameter of the coil body  15  is larger than an outer diameter of the core shaft  13  at the position at which the coil body  15  is joined. 
     The bulge portion  19  is joined to the stranded wire  16  at a position spaced distally from the distal end of the core shaft  13  and the distal end of the coil body  15 . An outer diameter of the bulge portion  19  is greater than an outer diameter of the core shaft  13  at a position at which the bulge portion  19  is joined to the core shaft  13 . Incidentally, material of the bulge portion  19  is also similar to that of the bulge portion  9  of the guidewire  1 . 
     An area of the coating agent  17  is illustrated by hatching in  FIG. 4 . As shown in  FIG. 4 , the coating agent  17  covers the core shaft  13 , the coil body  15  and the bulge portion  19  from a distal end of the guidewire  10  (which is at a distal side of the distal end of the bulge portion  19 ) to the proximal side of the proximal end of the coil body  15  except for the interior of the coil body  15 . 
     It is to ensure the flexibility of the distal end of the guidewire  10  not to allow the coating agent  17  to penetrate inside the coil body  15 . 
     The coating agent  17  can cover the core shaft  13  all the way to the proximal end of the core shaft  13  on the proximal side of the proximal end of the coil body  15 . Material of the coating agent  17  is similar to that of the coating agent  7  of the guidewire  1 . 
     Because the guidewire  10  comprises a core shaft  13 , a stranded wire  16  joined to a distal portion of the core shaft  13  so as to be located on a distal side of the core shaft  13  and including a plurality of wires, a coil body  15  having a distal end joined to the stranded wire  16  at a position spaced proximally from a distal end of the stranded wire  16  and a proximal end joined to the core shaft  13 , a coating agent  17  covering an outer periphery of the stranded wire  16 , the core shaft  13  and the coil body  15 , and a bulge portion  19  joined to the stranded wire  16  at a position spaced distally from a distal end of the coil body  5 , wherein the coating agent  17  covers the core shaft  13  and the coil body  15  from a distal side of the bulge portion  19  to a proximal side of the proximal end of the coil body  15  except for the interior of the coil body  15 , it is possible to ensure flexibility of the coil body  15  and a distal portion of the guidewire  10  and prevent the coating agent  17  from peeling from the stranded wire  16 , the core shaft  13  and the coil body  15  by the bulge portion  19  and the coil body  15 . 
     The bulge portion  19  may be joined to the distal end of the stranded wire  16  so that the distal end of the stranded wire  16  does not protrude from the bulge portion  19 . According to this configuration, it is possible to prevent the distal end of the stranded wire  16  from protruding from the coating agent  17  and damaging to the body tissue. 
       FIG. 5  is a longitudinal sectional view of a distal portion of a guidewire of the disclosed embodiments, and  FIG. 6  is a longitudinal sectional view near a stranded wire of the guidewire of  FIG. 5 . 
     Incidentally, portions common to the guidewire  10  will be denoted by the same reference numerals, and descriptions of the portions will be omitted. 
     The guidewire  20  of the disclosed embodiments is different from the guidewire  10  with respect to the connecting state between the stranded wire and the coating agent. That is, a coating agent  27  penetrates between a plurality of wires included in a stranded wire  26  to form a protruding portion  27   a  that protrudes from a gap between adjacent ones of the plurality of wires included in the stranded wire  26 . 
     The guidewire  20  increases bonding strength between the coating agent  27  and the stranded wire  26  by forming the protruding portion  27   a . Further, because an innermost portion of the protruding portion  27   a  in the radial direction of the guidewire has a longitudinal thickness that is greater than a spacing between adjacent wires, it is possible to further prevent the coating agent  27  from peeling from the stranded wire  26 . 
     As shown in  FIG. 5 , the stranded wire  26  includes a proximal end joined to a distal portion of the core shaft  13  by a brazing material  28  inside the coil body  15 , and extends distal to a distal end of the core shaft  13  and a distal end of the coil body  15 . Incidentally, the brazing material  28  may be a material similar to that of the brazing material  2  and the brazing material  4  of the guidewire  1 . 
     Because the coating agent  27  penetrates between a plurality of wires included in the stranded wire  26  in at least a portion of the stranded wire  26  that is not inside the coil body  15 , it is possible to further prevent the coating agent  27  from peeling from the stranded wire  26 . 
     The bulge portion  19  may be joined to the distal end of the stranded wire  26  so that the distal end of the stranded wire  26  does not protrude from the bulge portion  19 . According to this configuration, it is possible to prevent the distal end of the stranded wire  26  from protruding from the coating agent  27  and damaging to the body tissue.