Patent Publication Number: US-2013237962-A1

Title: Catheter assembly

Description:
CROSS REFERENCE TO RELATED APPLICATION  
     This application claims the priority of Japanese Patent Application No. 2010-006217, filed on Jan. 14, 2010 in the JPO (Japan Patent Office). Further, this application is the National Phase application of International Application No. PCT/JP2010/070396 filed Nov. 16, 2010, which designates the United States and was published in Japanese. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a catheter assembly, the distal end side of which is introduced into an introduction target part such as the coronary arteries, when used. 
     BACKGROUND ART 
     As a catheter assembly of which the distal end side is introduced into an introduction target part such as the coronary arteries in use, a catheter assembly having a tube-shaped outer member and a tube-shaped inner member at least partially inserted in a tube hole of the outer member has been known. 
     As the catheter assembly, for example, a configuration having a catheter as an outer member and an insertion assisting tool as an inner member has been disclosed in Patent Document 1. In this case, with the insertion assisting tool disposed such that a portion protrudes toward the distal end side from an opening at the front end of the catheter, the catheter assembly is introduced in a body and the insertion assisting tool is pulled out after being introduced. Further, a balloon catheter is newly inserted for the catheter left in a body and the affected area is repaired. 
     In the configuration of Patent Document 1, a guide wire is used when introducing a catheter assembly into a body, and the guide wire is inserted in a tube hole of the insertion assisting tool. In the configuration, the insertion assisting tool has a front end having a tube shape and a shaft. The shaft extends from the front end to a proximal end side and has an outer diameter smaller than that of the front end. Accordingly, it is possible to smoothly move the insertion assisting tool forward/backward in the catheter while decreasing the contact area between the inner circumferential surface of the catheter and the outer circumferential surface of the insertion assisting tool, in comparison to the configuration in which a tube hole for inserting a guide wire is formed throughout the axial line direction of the insertion assisting tool. Further, since the lumen of the front end is open to the proximal end side, it is possible to prevent the guide wire from locking to the catheter when pulling out or inserting the guide wire, with the insertion assisting tool inserted in the catheter, thereby making the operation easy. 
     Patent Document 1: Japanese Patent Application Laid-Open No. 2008-142351 
     However, in the configuration of Patent Document 1, when the catheter assembly is taken out from a body or replaced, with the front end of the guide wire left in the repair object part in the body, it is necessary to remove the entire catheter assembly from the body while keeping a portion of the guide wire at the proximal end side further than the catheter. And then, it is necessary to separate the catheter assembly while holding a portion of the guide wire that is exposed at the distal end side further than the catheter assembly. Therefore, the guide wire that is used is required to have a length equal to or more than the sum of the distance from the introduction start position to the repair object part in the body and the length of the catheter assembly. Thus it is necessary to use a guide wire having a large length. 
     DISCLOSURE OF THE INVENTION 
     The present invention has been made in consideration of the situations and it is an object to provide a catheter assembly that can increase the degree of freedom in selection of a guide wire to use. 
     Hereinafter, means useful to solve the problems will be described, if necessary, together with the operation, effect, and the like. 
     A catheter assembly of the first aspect of the invention: includes: an inner member having an inner hole through which a guide wire is inserted; and an outer member having an outer hole through which the inner member is inserted. The inner member has an inner opening, by which the inner hole is opened to the outside of the inner member, at a middle position in an axial line direction of the inner member. The inner opening is formed such that an inner open surface faces a proximal end side or inclines with respect to the axial line direction, and the outer member has an outer opening, by which the outer hole is opened to the outside of the outer member, at a middle position in an axial line direction of the outer member. The outer opening is formed such that an outer open surface faces a proximal end side or inclines with respect to the axial line direction, on the same line as the inner opening. 
     According to this configuration, since the inner opening and the outer opening are formed at the middle position of the catheter assembly in the axial line direction, it is possible to use a guide wire with a small length. In this case, the outer opening is formed on the same line as the inner opening and the inner opening and the outer opening have a component facing the proximal end side as the component that the opening surfaces face, such that the guide wire is less bent in the direction crossing the axial line direction when being inserted or drawn out and the work of inserting or drawing out can be smoothly performed. 
     The catheter assembly of the second aspect of the invention: in the first aspect of the invention, the inner member has an inner tube having the inner hole and the inner opening at the proximal end portion, and an inner shaft being provided to extend toward the proximal end side from the inner tube and having a dimension that is smaller than a dimension of the inner opening in a direction perpendicular to the axial line direction. The outer member has an outer tube having the outer hole and the outer opening at the proximal end portion, and an outer shaft being provided to extend toward the proximal end side from the outer tube and having a dimension that is smaller than a dimension of the outer opening in a direction perpendicular to the axial line direction. 
     According to this configuration, when the guide wire passes through the catheter assembly, the portion of the proximal end side further than the inner opening of the inner member or the portion of the proximal end side further than the outer opening of the outer member does not become an obstacle. 
     The catheter assembly of the third aspect of the invention: in the second aspect of the invention, includes: a contrast being provided at a position of the opening of the one of the inner member and the outer member, or a position adjacent thereto; and a joint part being provided at the other one of the inner member and the outer member and having a metal region welded to a metal region of the shaft of the other one of the inner member and the outer member, and moreover connecting the shaft with the corresponding tube by welding. The joint part is provided not to overlap the contrast portion in the axial line direction. 
     According to this configuration, it is possible to strongly connect the corresponding tube with the shaft, at the side where the joint part is disposed, in at least one with the joint part in the inner member and the outer member. In this case, since the joint part is disposed not to overlap the contrast portion, it is possible to perform the strong connection while showing the function of the contrast portion well. 
     The catheter assembly of the fourth aspect of the invention: in the second aspect of the invention, the outer tube has a joint part being provided at a position of the outer opening or a position adjacent thereto, and having a metal region welded to a metal region of the outer shaft, and moreover connecting the outer shaft to the outer tube by welding. According to this configuration, since it is possible to strongly connect the outer tube with the outer shaft and to contrast the joint part, it is possible to recognize the position of the outer opening, with the catheter assembly inserted in a body, through the contrasting. 
     The catheter assembly of the fifth aspect of the invention: in the fourth aspect of the invention, the inner opening is positioned further toward a distal end side than the outer opening when relative positions of the inner member and the outer member in the axial line direction are predetermined initial positions. The inner member has a contrast portion provided at the position of the inner opening or a position adjacent thereto, and the length of the joint part is set not to overlap the contrast portion in the axial line direction. According to this configuration, it is possible to show the function of the joint part without reducing the function of the contrast portion for the inner opening while using the joint part as a marker for contrasting the outer opening. 
     The catheter assembly of the sixth aspect of the invention: in the fourth or fifth aspect of the invention, the inner opening is positioned further toward a distal end side than the outer opening when relative positions of the inner member and the outer member in the axial line direction are predetermined initial positions. And the inner shaft has a rigidity reduction structure at the position overlapping the joint part in the axial line direction when the relative positions are the initial positions. The rigidity reduction structure exhibits reduced rigidity of the inner shaft than that on the proximal end side. According to this configuration, in the configuration where the joint part made of metal is disposed for the outer member, it is possible to suppress a local increase in rigidity by using the inner shaft. 
     The catheter assembly of the seventh aspect of the invention: in any one of the fourth to sixth aspects of the inventions, the joint part is formed to have a cylindrical shape around the axial line and an open surface of a proximal end side thereof inclines with respect to the axial line. The outer shaft has a tapered portion at a distal end portion thereof, the tapered portion is formed by crushing one side of the outer shaft to the other side with the axial line therebetween, and has a large width surface and an inclining surface. The large width surface includes a portion leveled with the portion positioned further toward the proximal end side than the tapered portion throughout the axial line direction and is made wider than the portion on the proximal end side. And the inclining surface is inclined to gradually decrease the distance from the large width surface toward the distal end side. The axial line direction of the outer shaft is the axial line direction of the outer tube as the large width surface is provided to be in contact from the inside with a portion, the portion being the inner circumferential surface of a tube wall defining the opening and the periphery of the proximal end side of the joint part and being in the same straight line of the proximal end portion of the opening. The joint part and the outer shaft are welded at the contact portion. 
     According to this configuration, as the large width surface is in contact from the inside with the inner circumferential surface of the joint part and welded, it is possible to increase the strength of connection while suppressing a step at the outer circumference of the joint part. Further, since the large width surface has a portion leveled with the proximal end side further than that throughout the axial line direction, it is possible to arrange the axial line direction of the outer shaft in the axial line direction of the outer tube, when the large width surface is in contact with the inner circumferential surface of the joint part. Further, in the configuration in which the opening of the proximal end side of the joint part is formed to be inclined, since the large width surface is in contact with the portion in the same straight line as the proximal end portion at the opening of the proximal end side and the inclining surface of the tapered portion faces the inside, it is possible to show excellent effect as described above while suppressing a decrease in passing performance of the guide wire at the outer opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1(   a ) is a front view showing the configuration of an outer catheter and  FIG. 1(   b ) is a front view showing the configuration of an inner catheter. 
         FIG. 2  is a vertical cross-sectional view of a distal end side of the inner catheter. 
         FIG. 3(   a ) is a partial front view enlarging an outer tube and the peripheral,  FIG. 3(   b ) is a vertical cross-sectional view enlarging the periphery of the joint of the outer tube and an outer shaft,  FIG. 3(   c ) is a front view showing a joint ring and the distal end side of the outer shaft, and  FIG. 3(   d ) is a view enlarging the joint of the joint ring and the outer shaft. 
         FIG. 4(   a ) is a front view of a catheter assembly when being inserted in a guiding catheter, with a guide wire inserted and  FIG. 4(   b ) is a cross-sectional view taken along line A-A. 
         FIG. 5  is an illustrative view for illustrating the shape when a catheter assembly is introduced in a left coronary artery. 
         FIG. 6  is a partial front view for illustrating another shape of the outer catheter. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, an embodiment when the present invention is applied to a catheter assembly will be described with reference to the drawings.  FIGS. 1(   a ) and  1 ( b ) are front views showing members constituting a catheter assembly  10 . 
     As shown in  FIGS. 1(   a ) and  1 ( b ), the catheter assembly  10  includes an outer catheter  11  disposed as an outer member and an inner catheter  12  disposed as an inner member. The outer catheter  11  is a catheter for delivering that is used to introduce a balloon catheter or the like which is not shown, into a peripheral stenosis affected area of a coronary artery. The inner catheter  12  is inserted and used in the outer catheter  11  when the outer catheter  11  is inserted in an affected area in a body. The inner catheter  12  is an insertion assisting tool that assists the insertion positioned ahead of the outer catheter  11 . The entire lengths of both the outer catheter  11  and the inner catheter  12  are 1500 mm, but may be larger or smaller. 
     The inner catheter  12  in both catheters  11  and  12  is described first with reference to  FIG. 1(   b ) and  FIG. 2 .  FIG. 2  is a vertical cross-sectional view of the distal end side (front end side) of the inner catheter  12 . 
     The inner catheter  12 , as shown in  FIG. 1(   b ), has an inner tube  21  that is the part from the distal end to the middle position of the proximal end side (base end side) and constitutes the distal end side of the inner catheter  12  and an inner shaft  22  constituting the proximal end side further than the inner tube  21 . The inner tube  21 , as shown in  FIG. 2 , has a tube hole (lumen)  23  formed throughout the axial line direction by opening both the distal end portion and the proximal end portion, as an inner hole, and generally has a tube shape. The tube hole  23  is used to insert a guide wire. Hereinafter, the tube hole  23  is also referred to as a guide wire tube hole (guide wire lumen)  23 . 
     The inner tube  21  is formed such that the outer diameter and the diameter of the hole of the guide wire tube hole  23  gradually decrease toward the distal end side from the middle position in the axial line direction. The distal end portion of the inner tube  21  is configured by a soft tip  24  having constant outer diameter and inner diameter throughout the axial line direction. That is, the inner tube  21  has a base tube  25  and the soft tip  24  constituting the distal end side further than the base tube  25 . The base tube  25  has a tapered region  25   a  of which the diameter gradually decreases toward the soft tip  24  from the middle position in the axial line direction. Further, the guide wire tube hole  23  is formed by the tube holes of the base tube  25  and the soft tip  24  that communicate with each other, a proximal end opening  23   a  of the tube hole  23  is formed by the distal end portion of the soft tip  24 , and a proximal end opening  23   b  of the tube hole  23  is formed by the proximal end portion of the base tube  25 . 
     Both the base tube  25  and the soft tip  24  are made of PEBAX (Polyether Block amide) copolymer, but the soft tip  24  is formed to be more flexible than the base tube  25 . The base tube  25  and the soft tip  24  are thermally welded. Further, a marker  26  for a tapered region that is made of a material such as tungsten that blocks radiation (X-rays) and is formed in a cylindrical shape, as shown in  FIG. 1(   b ), is disposed at the end of the proximal end side of the tapered region  25   a  of the base tube  25 . 
     The inner shaft  22  fixed to the inner tube  21 , as shown in  FIG. 2 , has a hypotube  31  formed in a tube shape. The inner shaft  22  also has an extending tube  32  covering the outer circumference of the distal end portion of the hypotube  31  and extending the inner shaft  22  to the distal end side further than the hypotube  31 . The hypotube  31  is made of metal such as stainless steel or a Ni—Ti alloy in a tube shape and the extending tube  32  is made of synthetic resin such as polyamide in a tube shape. The members  31  and  32  are connected by the extending tube  32  thermally welded to the hypotube  31 . Further, the outer circumferential surface of the hypotube  31  may be coated with synthetic resin. In the hypotube  31  and the extending tube  32 , the extending tube  32  is thermally welded to the base tube  25 , such that the inner shaft  22  is connected to the inner tube  21 . 
     Describing the configuration according to the connection in detail, a connection tube  27  having the same outer diameter and inner diameter as those of the extending tube  32  is formed from the proximal end opening  23   b  of the guide wire tube hole  23  to the position of the tapered region  25   a,  in the base tube  25 . A connection tube hole (connecting lumen)  28  extending in the axial line direction is formed at the connection tube  27 . The distal end side of the connection tube hole  28  is closed by a wall constituting the tapered region  25   a  but the proximal end side is open. The extending tube  32  is thermally welded to the connection tube  27  such that a shaft-side tube hole (shaft-side lumen)  33  that is configured by the tube holes (lumens) of the hypotube  31  and the extending tube  32  communicates with the connection tube hole  28 . 
     A core material  34  having an outer diameter smaller than those of the tube holes  28  and  33  is disposed to cross the interfaces of both the tube holes  28  and  33  by using communication of the connection tube hole  28  and the shaft-side tube hole  33 . The core material  34  is a wire made of metal such as stainless steel or a Ni—Ti alloy and bonded to the inner circumferential surface of the hypotube  31 . Further, the end of the distal end side reaches even the middle position of the base tube  25  in the axial line direction. As the core material  34  is disposed, kink resistance of the connection portion of the inner tube  21  and the inner shaft  22  is improved. 
     Note that the core material  34  is not fixed with respect to the connection tube hole  28  or the extending tube  32 , but may be fixed. In this case, the core material  34  is integrated well to the connection tube  27  and the extending tube  32 . As a more preferable fixing configuration, a configuration of filling the connection tube hole  28  or the tube hole of the extending tube  32  with synthetic resin, with the core material  34  inserted, or a configuration of making the outer diameter of the core material  34  and the diameters of the connection tube hole  28  and the tube hole of the extending tube  32  substantially the same to forcibly press the core material  34  into the tube holes, is considered. 
     Further, as the core material  34  is disposed to be inserted in the inner tube  21  from the hypotube  31 , a local change in rigidity at the position of the distal end portion of the hypotube  31  is suppressed and the kink resistance is also improved. In addition, as means for suppressing a local change in rigidity at the distal end portion of the hypotube  31 , an inner side rigidity reduction structure is disposed for the hypotube  31 , other than the core material  34 . 
     Describing the inner side rigidity reduction structure in detail, as shown in  FIG. 1(   b ) and  FIG. 2 , an inner side rigidity reduction region  35  is formed by a spiral slit  35   a  from the middle position in the axial line direction to the distal end portion, in the hypotube  31 . The slit  35   a  is formed such that the pitch between slits adjacent to each other in the axial line direction decreases at the distal end side relatively to the proximal end side. That is, the inner side rigidity reduction region  35  is formed such that the rigidity of the hypotube  31  gradually decreases toward the distal end side. Further, as shown in  FIG. 2 , the slit  35   a  is also formed at the position covered by the extending tube  32 , in the hypotube  31 . 
     The inner shaft  22  in the above configuration has a substantially constant outer diameter throughout the axial line direction, except for an inner grip  36  disposed at the end of the proximal end side and the outer diameter is substantially the same as the outer diameter of the connection tube  27 , as described above. 
     Since the proximal end opening  23   b  of the guide wire tube hole  23  is formed at the proximal end portion of the inner tube  21 , the position is the middle position of the inner catheter  12  in the axial line direction. That is, an inner port for drawing out the guide wire at the proximal end side is formed at the middle position of the inner catheter  12  in the axial line direction. Further, in the following description, the proximal end opening  23   b  is also referred to as an inner opening  23   b  for the convenience of description. 
     The inner opening  23   b  is formed with an inner open surface at an angle with respect to the axial line direction, and a wide open area is ensured. Further, the inner shaft  22  is disposed to be biased at the portion that is the most proximal end side in the inclined inner opening  23   b.  The portion that is the most distal end side in the inner opening  23   b  is opposite to the inner shaft  22  with an axial line therebetween. Therefore, the inner opening  23   b  has a directional component facing the proximal end side and to release the guide wire tube hole  23  to a side. Further, the inner opening  23   b  has a dimension in the direction perpendicular to the axial line direction that is larger than the dimension of the inner shaft  22  and the difference is equal to or more than the outer diameter of the guide wire to be used. 
     A marker  37  for an inner opening is disposed as a contrast portion, as shown in  FIG. 1(   b ) and  FIG. 2 , at a position close to or adjacent to the proximal end side with respect to the inner opening  23   b  in the inner shaft  22 . The marker  37  is made of a material such as tungsten blocking radiation in a cylindrical shape. The position where the marker  37  is disposed is a position spaced at 230 mm to the proximal end side with respect to the distal end portion of the inner catheter  12 . The position is spaced to the distal end side further than the distal end portion of the hypotube  31 . As the marker  37  for an inner opening is disposed, it is possible for an operator to know the position of the inner opening  23   b  even though the catheter assembly  10  is inserted in a body. 
     Note that the material of the marker  37  for an inner opening is not limited to tungsten and may be gold, platinum, iridium, barium, barium sulfate, bismuth, bismuth oxide, bismuth oxycarbonate, bismuth subcarbonate, zirconium oxide, tantalum, a cobalt chrome alloy, sodium iodide, silver-protein colloid, silver iodide-gelatin colloid, stainless steel, titanium or the like. Further, the marker  37  for an inner opening may be disposed at the periphery of the inner opening  23   b.  A marker  38  for visually checking the insertion amount of the inner catheter  12  in a body is also disposed at the proximal end side of the inner shaft  22 , as shown in  FIG. 1(   b ). 
     Next, the outer catheter  11  is described. 
     The outer catheter  11 , as shown in  FIG. 1(   a ), has an outer tube  41  constituting the distal end side of the outer catheter  11  from the distal end to the middle position of the proximal end side (base end side) and an outer shaft  42  constituting the proximal end side further than the outer tube  41 . The detailed configuration of the outer tube  41  and the outer shaft  42  are shown in  FIG. 3 . 
       FIG. 3(   a ) is a partial front view enlarging the outer tube  41  and the periphery,  FIG. 3(   b ) is a vertical cross-sectional view enlarging the connection portion between the outer tube  41  and the outer shaft  42  and the periphery,  FIG. 3(   c ) is a front view showing a joint ring  51  and the distal end side of the outer shaft  42 , and  FIG. 3(   d ) is a view enlarging the connection portion between the joint ring  51  and the outer shaft  42 . 
     The outer tube  41 , as shown in  FIG. 3(   a ) and  FIG. 3(   b ), has an outer tube hole (outer lumen)  43  formed throughout the axial line direction by opening both the distal end portion and the proximal end portion, as an outer hole, and generally has a tube shape. The outer tube hole  43  is used to insert the inner catheter  12  and a guide wire, and a catheter such as a balloon catheter that is used for an affected area is inserted, when the inner catheter  12  is separated. 
     The outer tube hole  43  has a constant hole diameter substantially throughout the axial line direction. The hole diameter of the outer tube hole  43  is slightly larger than the outer diameter of the region between the tapered region  25   a  and the inner opening  23   b  in the inner tube  21 , that is, the maximum outer diameter of the inner tube  21 . In the outer tube  41 , a base layer  44  including the outer circumferential surface is made of PEBAX, such that flexibility that allows following a curved blood vessel is ensured. And a friction reduction layer  45  made of Teflon (registered trademark) is formed on the inner circumferential surface of the outer tube  41  to reduce resistance when the inner catheter  12  or other catheters slides in the outer tube hole  43 . The friction reduction layer  45  is disposed to cover the entire inner circumferential surface or may be partially disposed in a portion where sliding is easy to occur but not in a portion where sliding is difficult to occur. 
     The material of the base layer  44  is not limited to a polyamide elastomer such as PEBAX, and polyethylene, polyethylene terephthalate, polypropylene, polyurethane, polyimide, polyimide elastomer, silicone rubber, natural rubber, or the like may be used. Further, the materials may be used for the inner tube  21 . In addition, the material of the friction reduction layer  45  is not limited to Teflon, and other fluorine-based resin or hydrophilic polymer such as maleic anhydride copolymer may be used. 
     The outer tube  41  has predetermined flexibility, as described above, but has an outer side tip  46  having higher flexibility at the distal end portion than the proximal end side. Accordingly, even if the distal end portion of the outer tube  41  comes in contact with the wall of a blood vessel, load applied to the wall of the blood vessel decreases. The outer side tip  46  is made of the same material as that of the base layer  44 , but may be made of other materials. 
     The outer tube  41  has a length of 300 mm that is larger than the length of the inner tube  21 . Therefore, when the inner tube  21  is inserted in the outer tube  41  such that the soft tip  24  and the tapered region  25   a  are positioned at the distal end side further than the outer tube  41 , the proximal end portion of the inner tube  21  is positioned at the distal end side further than the proximal end portion of the outer tube  41 . The relative positions are described in detail below. 
     The outer shaft  42  fixed to the outer tube  41  is made of metal such as stainless steel or a Ni—Ti alloy in a cylindrical shape. The outer shaft  42 , as shown  FIG. 3(   b ) and  FIG. 3(   c ), is connected to the outer tube  41  by the joint ring  51  disposed as a joint part. Further, the outer circumferential surface of the outer shaft  42  may be coated with synthetic resin within a range not interfering with the connection. 
     The configuration according to the connection is described in detail. The joint ring  51  is made of metal such as stainless steel in a cylindrical or tube shape and a joint tube hole (joint lumen)  52  is open at both ends in the axial line direction. In this case, as shown in  FIG. 3(   c ), an opening  52   a  is formed such that the open surface is perpendicular to the axial line of the joint ring  51 , while the other opening  52   b  is formed such that the open surface inclines with respect to the axial line of the joint ring  51 . Further, the joint ring  51  has constant outer diameter and inner diameter, except for the place where the other opening  52   b  is formed. Note that in the following description, the other opening  52   b  is also referred to as a joint side-inclining opening  52   b.    
     The joint ring  51  is disposed at the outer tube  41  such that the joint side-inclining opening  52   b  becomes the proximal end side and the outer shaft  42  is jointed with respect to the opening  52   b.  The outer shaft  42  deforms such that the end of the distal end portion is tapered. 
     The tapered portion  53 , as shown in  FIG. 3(   c ) and  FIG. 3(   d ), is not formed such that the entire circumferential surface is tapered toward the front end, but formed to be tapered by crushing one side to the other side with the axial line therebetween. In this case, the tapered portion  53  has a large width surface  53   a  and an inclining surface  53   b.  The large width surface  53   a  includes a portion leveled with the portion positioned further toward the proximal end side than the tapered position  53  throughout the axial line direction and is made wider than the portion on the proximal end side. The inclining surface  53   b  is inclined to gradually decrease the distance from the large width surface  53   a  toward the distal end side. 
     The tapered portion  53  is disposed such that the large width surface  53   a  is in contact from the inside with the inner circumferential surface of the peripheral portion inclining to the proximal end side of the join side-inclining opening  52   b,  and the inner circumferential surface and the large width surface  53   a  are bonded. The bonding is performed by radiating a laser to a plurality of positions (in detail, two positions) to generate welded positions at a plurality of positions spaced in the axial line direction. Thus, the joint ring  51  and the outer shaft  42  are strongly fixed. Note that in the large width surface  53   a,  the curvature around the axis and the curvature of the inner circumferential surface of the contact portion are substantially constant. 
     Describing the bonding positions in more detail, the most front end of the tapered portion  53  is positioned at a proximal end side further than the periphery that is the most distal end side of the joint side-inclining opening  52   b and not to be covered by the periphery. Accordingly, it is easy to radiate a laser and to suppress the area of the region where the joint ring  51  and the outer shaft  42  overlap each other in the axial direction, thereby reducing influence on the rigidity. 
     However, as the overlap region between the joint ring  51  and the outer shaft  42  is narrowed in the configuration, they may not be strongly fixed, but with the large width surface  53   a  of the tapered portion  53  in contact with the periphery of the joint side-inclining opening  52   b,  it is possible to widen the range of the welded position, as compared with when the large width surface  53   a  is not generated. Therefore, sufficient bonding strength is achieved. Further, as the large width surface  53   a  is bonded while being in contact, the axial line direction of the outer shaft  42  is parallel with the axial line direction of the joint ring  51  (that is, the axial line direction of the outer catheter  11 ). 
     When further increasing the bonding strength, it is considered to integrally form the inclining portion, which is the most proximal end side of the periphery of the joint side-inclining opening  52   b,  with the extending portion that further extends to the proximal end side from it. 
     The joint ring  51  connected with the outer shaft  42 , as shown in  FIG. 3(   b ), is embedded in a base layer  44  of the outer tube  41 . That is, the joint ring  51  has a length set to be smaller than the length of the base layer  44  and the joint ring  51  is positioned at the middle position of the outer tube  41  in the axial line direction. 
     In the configuration with the joint ring  51  embedded in the base layer  44 , a local increase in rigidity may be generated at the position where the joint ring  51  is disposed. Accordingly, an outer side rigidity reduction structure is disposed at the joint ring  51 . 
     For the outer side rigidity reduction structure, in detail, as shown in  FIG. 3(   c ), an outer rigidity reduction region  54  is formed by a spiral slit  54   a,  from the distal end side of the joint ring  51  in the axial line direction to the portion positioned ahead of the joint side-inclining opening  52   b.  The slit  54   a  is formed such that the pitch between the slits adjacent to each other in the axial line direction is small at the distal end side relative to the proximal end side. That is, the outer side rigidity reduction region  54  is formed such that the rigidity of the joint ring  51  gradually decreases toward the distal end side. Therefore, it is possible to suppress a local increase in rigidity and improve kink resistance. 
     A method of embedding a joint ring  51  into a base layer  44  is described. 
     First, as a preparation process, the outer shaft  42  is bonded with respect to the joint ring  51 . Further, an outer layer tube made of PEBAX as a single layer tube and an inner layer tube made of PEBAX and Teflon as an inner-and-outer double layer tube are prepared. Note that the lengths of the outer layer tube and the inner layer tube are the same. 
     Thereafter, a process of disposing the outer layer tube and the inner layer tube to fit the joint ring  51  between the layers in the radial direction and a process of thermally welding the inner and outer overlap portions of the outer layer tube and the inner layer tube are performed. The thermal welding is performed by using a shaft for thermal welding or the like such that the inner diameter of the outer tube hole  43  becomes constant in the axial line direction, except for the proximal end side where the tapered portion  53  of the outer shaft  42  exists. As the inner diameter becomes constant, a step is formed on the outer circumferential surface of the outer tube  41 , but the thickness of the base layer  44  may be set such that the step is not generated. 
     As the thermal welding is performed, as described above, the joint ring  51  is fitted by the base layer  44  from the distal end side and the proximal end side, such that the joint ring  51  is prevented from displacing from the position in the axial line direction. Further, in the thermal welding, the outer layer tube is heated from the outer circumferential surface, and the heating is not performed on the outer side rigidity reduction region  54  of the joint ring  51 . Therefore, it is possible to show well the function of the outer side rigidity reduction region  54 . Meanwhile, heating is performed on the region where the outer side rigidity reduction region  54  is not disposed and the region where the tapered portion  53  of the outer shaft  42  is disposed. Therefore, the portions where the base layer  44  is thermally welded exist in the joint ring  51  or the outer shaft  42 , such that the connection can be strongly performed. 
     The joint side-inclining opening  52   b  is formed at the joint ring  51 , as described above, and a proximal end opening  43   a  of the outer tube hole  43  exists at a position further toward the proximal end side than the position of the inclining opening  52   b  at the outer tube  41 . Since the proximal end opening  43   a  is formed at the proximal end side of the outer tube  41 , the position is the middle position of the outer catheter  11  in the axial line direction. A guide wire that is used when the catheter assembly  10  is inserted into a body passes through the outer tube hole  43  at a position further toward the proximal end side than the inner opening  23   b,  in addition to passing the guide wire tube hole  23  of the inner catheter  12 . In this case, as the proximal end opening  43   a  of the outer tube hole  43  is formed at the position, it can be stated that the outer port for drawing out the guide wire passing through the outer tube hole  43  out of the outer catheter  11  at the proximal end side is formed at the middle position of the outer catheter  11  in the axial line direction. Note that in the following description, the proximal end opening  43   a  is also referred to as an outer opening  43   a  for the convenience of description. 
     The outer opening  43   a  is formed with an outer open surface at an angle with respect to the axial line direction, and a wide open area is ensured. Further, the portion that is the most distal end side of the outer opening  43   a  is opposite the outer shaft  42  with the axial line therebetween. Therefore, the outer opening  43   a  has a component facing the proximal end side and is shaped to release the outer tube hole  43  to a side. 
     The outer opening  43   a  has a dimension in the direction perpendicular to the axial line direction that is larger than a dimension of the outer shaft  42  and the difference is equal to or more than the outer diameter of the guide wire to be used. Further, an inclining surface  53   b  is formed at the opposite side of the large width surface  53   a  in the tapered portion  53  of the outer shaft  42 . The inclining surface  53   b  goes to the outer circumference as the inclining surface  53   b  goes to the distal end side. Accordingly, the operability of the guide wire is improved. 
     The joint ring  51  made of stainless steel is disposed at the position adjacent to the outer opening  43   a,  as described above. Since stainless steel blocks radiation, when radiation is irradiated with the catheter assembly  10  inserted in a body, the joint ring  51  is contrasted, such that it is possible to know the position of the outer opening  43   a.  That is, the joint ring  51  has the function of a marker for showing the position of the outer opening  43   a.  Further, since the joint ring  51  has strength higher than that of the base layer  44  in the radial direction, the outer opening  43   a  is not easily crushed. That is, the joint ring  51  has the function of a shape-holding member for making the outer opening  43   a  difficult to be crushed. 
     Further, the outer shaft  42 , as shown in  FIG. 1(   a ), has the outer diameter that is substantially constant throughout the axial line direction, except for the tapered portion  53  disposed at the end of the distal end side and the outer grip  47  disposed at the end of the proximal end side. In detail, it is 0.5 mm and this is the same or substantially the same as the outer diameter of the hypotube  31  of the inner shaft  22 . In addition, two markers  48  for visually checking the amount of insertion of the outer catheter  11  in a body are disposed at the proximal end side of the outer shaft  42 . One of the markers  48  is formed at the position of the proximal end side at 1000 mm from the distal end portion of the outer catheter  11 . The position corresponds to the position where the outer catheter  11  starts to come out from a guiding catheter that is described below. Further, the other marker  48  is formed at the position of the proximal end side at 1200 mm from the distal end portion of the outer catheter  11 . The position is for checking that another catheter such as a balloon catheter reaches the position of the outer opening  43   a.    
     Next, when the catheter assembly  10  is formed by inserting the inner catheter  12  with respect to the outer catheter  11  is described with reference to  FIG. 4  and  FIG. 5 . 
       FIG. 4(   a ) is a front view of the catheter assembly  10  when a guide wire  61  is inserted into the catheter assembly  10  and the catheter assembly  10  is inserted in the guiding catheter  62  and a vertical cross-sectional view of the guiding catheter  62  is shown. Further,  FIG. 4(   b ) is a cross-sectional view taken along line A-A in  FIG. 4(   a ). In addition,  FIG. 5  is an illustrative view for illustrating the shape when the catheter assembly  10  is introduced in a left coronary artery BV 4 . 
     As shown in  FIG. 4(   a ), in the initial state of the catheter assembly  10 , the soft tip  24  and the tapered region  25   a  of the inner catheter  12  that is inserted in the outer tube  41  protrude to the distal end side further than the outer tube  41 . The interface or the periphery of the tapered region  25   a  of the inner tube  21  and the region of the more proximal end side is positioned at the opening portion of the distal end side of the outer tube  41 . This is the initial state of the catheter assembly  10 . 
     As the inner catheter  12  goes before the outer catheter  11 , as shown in  FIG. 5 , the distal end portion of the guiding catheter  62  is disposed at the inlet of the left coronary artery BV 4  through a descending aorta BV 1 , an aortic arch BV 2 , and an ascending aorta BV 3 . When the catheter assembly  10  is protruded toward the distal end side from the state and inserted in the left coronary artery BV 4 , it is possible to allow the soft tip  24  first to follow the curved blood vessel and the passing performance can be increased. Further, when there is an occlusion portion, it is possible to slowly widen the occlusion portion from the soft tip  24  side. Note that the operation of making the outer catheter  11  go before the guiding catheter  62  is performed within a range where the outer opening  43   a  does not deviate from the guiding catheter  62 . 
     Returning to the description of  FIG. 4 , in the initial state of the catheter assembly  10 , the outer opening  43   a  of the outer catheter  11  is disposed at a position further toward the proximal end side than the inner opening  23   b  of the inner catheter  12 . The position of the outer opening  43   a  is the middle position of the catheter assembly  10  in the axial line direction. In more detail, the position of the outer opening  43  is a position further toward a distal end side than the middle position of the entire length of the catheter assembly  10 , and further toward a distal end side than a quarter from the distal end side of the catheter assembly  10 . As the position of the outer opening  43   a  is set, as described above, when the catheter assembly  10  is introduced after the guide wire  61  goes first, or when the catheter assembly  10  or the outer catheter  11  is replaced after the catheter assembly  10  is introduced, it is possible to suppress the length of the guide wire  61 , which is required to hold the guide wire  61  with hands at both sides in the axial line direction with the outer tube  41  therebetween, to be small. As a result, even the guide wire  61  of which the entire length is small can be used. 
     In the configuration in which the relative positions of the inner opening  23   b  and the outer opening  43   a  are the positions described above in the initial state, the regions that the guide wire  61  passes through are the guiding tube hole (guiding lumen)  62   a  formed at the guiding catheter  62 →outer tube hole  43 →guide wire tube hole  23 , when seen from the proximal end side. That is, when the guide wire  61  is inserted from the proximal end side, the transverse area of the passed regions gradually decreases. Accordingly, it is possible to easily introduce the guide wire  61  to the distal end side. 
     However, when the positional relationship of the openings  23   b  and  43   a  is set, as described above, the outer shaft  42  and the inner shaft  22  are parallel with each other at the proximal end portion of the outer opening  43   a  and the left space in the guiding tube hole  62   a  is narrowed at the proximal end portion of the outer opening  43   a.  For this configuration, as shown in  FIG. 4(   b ), the outer diameters of the shafts  22  and  42  are set such that the left space in the guiding tube hole  62   a  includes a space sufficiently larger than the transverse cross-section of the guide wire  61 . Therefore, it is possible to smoothly draw out the guide wire  61  out of the outer opening  43   a  to the proximal end side or insert the guide wire  61  into the outer hole  43  through the outer opening  43   a  from the proximal end side. 
     Further, the outer opening  43   a  is disposed on the same line as the inner opening  23   b,  the open surfaces of the openings  23   b  and  43   a  are inclined, and the directional components facing the proximal end side are included in the directional components that the open surfaces face. Therefore, when the guide wire  61  introduced in the outer tube hole  43  from the outer opening  43   a  further goes, the front end of the guide wire  61  becomes easily introduced into the inner opening  23   b.  Similarly, the guide wire  61  forcibly pushed out of the inner opening  23   b  to the outer tube hole  43  becomes easily drawn out of the outer catheter  11  through the outer opening  43   a.    
     Note that, when the catheter assembly  10  is introduced toward an affected area, the catheter assembly  10  may be forcibly inserted in the natural state or only the inner catheter  12  may be inserted into the affected area first within a range in which the inner opening  23   b  does not deviate from the outer catheter  11  to the distal end side and then the outer catheter  11  may be forcibly inserted. In the latter case, the relative positions of the inner opening  23   b  and the outer opening  43   a  are different from the natural state, but the inner opening  23   b  keeps positioned further toward the distal end side than the outer opening  43   a.    
     Next, the positional relationship between the marker  37  for an inner opening and the joint ring  51  is described with reference to  FIG. 1 . 
     As described above, in the natural state of the catheter assembly  10 , the inner opening  23   b  is disposed at a position further toward the distal end side than the outer opening  43   a.  In this case, the marker  37  for an inner opening that can show the position of the inner opening  23   b  under radiation is spaced by a distance L further toward the distal end side than the joint ring  51  that can show the position of the outer opening  43   a.  That is, in the configuration in which the joint ring  51  is disposed to be able to show the position of the outer opening  43   a,  the length of the joint ring  51  is set not to overlap the marker  37  for an inner opening. Accordingly, the marker  37  for an inner opening is individually contrasted, and in the configuration where the joint ring  51  is disposed, it is possible to clearly know the position of the inner opening  23   b.    
     In particular, in the work of introducing the catheter assembly  10 , the relative positions of the inner catheter  12  and the outer catheter  11  in the axial line direction may be changed. As described above, the change in relative position is generated when the inner catheter  12  goes first to a position further toward the distal end side than the position in the natural state. Therefore, in the change in relative position, the marker  37  for an inner opening is disposed to be further spaced from the joint ring  51  and it is possible to still contrast the marker  37  well. 
     Next, similarly, the positional relationship between the inner side rigidity reduction region  35  and the joint ring  51  is described with reference to  FIG. 1 . 
     In the natural state of the catheter assembly  10 , the inner shaft  22  passes the position where the joint ring  51  of the outer tube  41  is disposed. Here, the inner side rigidity reduction region  35  exists in the passed region, as described above, and an overlap region D of the joint ring  51  and the inner side rigidity reduction region  35  exists. Accordingly, the rigidity locally increases at the position of the joint ring  51  in the outer catheter  11 , the rigidity decreases at the position of the inner catheter  12  and the influence of an increase in rigidity due to the joint ring  51  can be suppressed in the catheter assembly  10 . 
     Note that the distal end portion of the rigidity reduction region  35  is positioned further toward the proximal end side than the distal end portion of the joint ring  51 , but it is not limited thereto and may be positioned at the same position in the axial line direction or maybe positioned at the distal end side. 
     According to the present embodiment described above, the following excellent effects are shown. 
     As the inner opening  23   b  and the outer opening  43   a  are formed at the middle position of the catheter assembly  10  in the axial line direction, it is possible to use the guide wire  61  of which the entire length is small. In this case, the inner opening  23   b  is formed at an angle to have a directional component facing the proximal end side in the direction that the open surface faces. The outer opening  43   a  is formed on the same line as the inner opening  23   b,  and is formed at an angle to have a directional component facing the proximal end side in the direction that the open surface faces. Accordingly, it is possible to easily draw out or insert the guide wire  61 . 
     Since the outer tube  41  and the outer shaft  42  are connected by using the joint ring  51 , it is possible to increase the connection strength well. In particular, in the catheter assembly  10 , the inner catheter  12  is introduced with the outer catheter  11 , but the outer catheter  11  is used to introduce another catheter while being independently held. Therefore, it is considered that large load is applied to the connection portion of the tube  41  and the shaft  42 , at the outer catheter  11  in comparison to the inner catheter  12 . Accordingly, resistance against the load is increased by using the joint ring  51 , as described above. 
     Meanwhile, for the inner catheter  12 , the hypotube  31  made of metal and the extending tube  32  made of resin continuing from the inner tube  21  are connected by thermally welding the extending tube  32 , without using the joint ring  51 . It is possible to suppress a local increase in rigidity at the middle position of the outer tube  41  in the axial line direction by applying the configuration to a configuration in which the inner opening  23   b  is disposed in the outer tube  41  in the initial state (the state when the relative positions of the catheters  11  and  12  are the initial positions). Further, when showing the operational effect, it may be possible to connect the extending tube  32  with the hypotube  31  by using an adhesive and it may be possible to directly connect the hypotube  31  to the inner tube  21  without using the extending tube  32 . 
     In the configuration in which the outer tube  41  and the outer shaft  42  are connected by using the joint ring  51 , the length of the joint ring  51  is set such that the marker  37  for an inner opening does not overlap the joint ring  51 . Therefore, it is possible to contrast the marker  37  for an inner opening well. 
     The inner side rigidity reduction region  35  is formed at the inner shaft  22  such that the overlap region D is generated between the joint ring  51  and the inner shaft  22 . Accordingly, it is possible to suppress the influence on an increase in rigidity due to the existence of the joint ring  51 . 
     The present invention is not limited to that described in the embodiment, and for example, may be implemented as follows. 
     (1) In the configuration of  FIG. 6  that is an applicable modified example, a coil  65  made of metal is disposed at the outer tube  41  of the outer catheter  11 . The coil  65  is embedded in the base layer  44 , in the same axial line as the outer tube  43 , from the distal end portion of the outer tube  41  to the distal end of the joint ring  51 . Accordingly, the strength of the outer tube  41  in the radial direction increases and the outer tube  41  is not easily crushed in use. 
     Further, it is possible not to reduce flexibility in the direction crossing the axial line direction of the outer tube  41 , by making the outer diameter of the metal wire of the coil  65  smaller than that of the core material  34  or the guide wire  61  and widening the gap of the adjacent portions in the axial line direction more than the pitch of the slit  54   a  formed at the joint ring  51 . 
     Further, a platinum wire maybe used for the coil  65 . In this case, it is possible to know the entire length of the outer tube  41  under radiation. Even in the configuration, it is possible to prevent the marker  37  for inner opening from be covered by the coil  65  by setting the outer diameter or the gap of the metal wire of the coil  65  described above. 
     (2) It may be possible to perform a structure or coating that reduces locking to the inner tube  21  or another catheter, at the side opposite to the side where the outer shaft  42  is disposed, at the periphery of the outer opening  43   a,  that is, at the distal end side of the periphery. As the structure of reducing locking, for example, a configuration of shaping the distal end side of the periphery of the outer opening  43   a  such that the contact area with the inner tube  21  or another catheter becomes small, is considered. 
     (3) The inner opening  23   b  and the outer opening  43   a  are not limited to the configuration in which the open surfaces are inclined with respect to the axial line direction, and at least one of them may be formed to be perpendicular to the axial line direction. Further, at least one of them may be formed in a flare shape toward the proximal end side. 
     (4) The configuration of connecting the tube with the shaft by using the joint ring  51  may be applied to the inner catheter  12 , and in this configuration, the configuration of the inner catheter  12  of the embodiment may be applied as a configuration for connecting the tube with the shaft in the outer catheter  11 . In this case, it may be possible to dispose the outer opening  43   a  at a position further toward the distal end side than the inner opening  23   b  in the initial state of the catheter assembly  10 . In the configuration, when a marker for contrast is separately disposed for the outer opening  43   a,  it is preferable to dispose the joint ring of the inner catheter  12  not to overlap the marker in the axial line direction. Further, when the configuration of the joint ring  51  is applied to the inner catheter  12 , it is possible to improve the passing performance of the guide wire  61  while implementing strong connection by using the configuration according to the large width surface  53   a  and the inclining surface  53   b.    
     (5) The inner side rigidity reduction region  35  or the outer side rigidity reduction region  54  is not limited to the configuration formed by the spiral slits  35   a  and  54   a.  The region  35  and  54  may be configured to be formed by a straight slit or may be configured to be formed in a mesh shape, and may be configured to be formed by reducing the thickness or the outer diameter toward the distal end side. 
     (6) The joint ring  51  is not limited to the continuous cylindrical shape around the axis and may have a disconnected portion at the middle position around the axis. Further, the rigidity in the radial direction reduces, but it may be possible to use a joint plate (or joint piece) made of metal instead of the joint ring  51  when suppressing a local increase in rigidity. 
     (7) The usage of the catheter assembly  10  is not limited to the usage for delivering another catheter such as a balloon catheter, and for example, the outer catheter  11  may be configured to be used as an aspiration catheter and the inner catheter  12  may be configured to be used as an insertion assisting tool. Further, the catheter assembly  10  may be used to deliver a self-expanding type of stent or the catheter assembly  10  may be used to open up an occlusion part or a narrowed part by using the distal end portion of the inner catheter  12  or the distal end portion of the outer catheter  11 .