Patent Publication Number: US-2012041261-A1

Title: Balloon catheter and balloon catheter assembly

Description:
This application is a continuation of International Application No. PCT/JP2010/053826 filed on Mar. 9, 2010, and claims priority to Japanese Application No. 2009-075218 filed on Mar. 25, 2009, the entire content of both of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention generally relates to a balloon catheter and a balloon catheter assembly provided with such balloon catheter. 
     BACKGROUND DISCUSSION 
     Conventionally, in falloposcopic tuboplasty for treating obstruction or stenosis of a fallopian tube under falloposcopy, a balloon catheter is used with a falloposcope. A known balloon catheter used in this regard includes an outer catheter, an inner catheter inserted in the outer catheter and movable along the longitudinal direction thereof, and an inflatable and contractible balloon member for connecting a distal portion of the inner catheter and a distal portion of the outer catheter to each other. An example of this catheter is disclosed in Japanese Patent No. 2813463. 
     The balloon member in the balloon catheter described in this patent projects from the distal end of the outer catheter by an amount which varies according to the amount of movement of the inner catheter relative to the outer catheter, and the balloon member is inflated and contracted in the projecting state. The balloon catheter configured in this way is used in the state in which a falloposcope is inserted through the inner catheter. 
     The disclosed balloon catheter also includes graduations indicative of the position of the falloposcope relative to the balloon member in the longitudinal direction of the catheter. Even with the graduations thus provided, however, misreading of the graduations can occur, and so the falloposcope may excessively project from the distal end of the balloon member, possibly resulting in damage of the fallopian tube by the projecting falloposcope or damage (cracking) of the falloposcope itself in contact with the fallopian tube. 
     SUMMARY 
     According to one aspect, a balloon catheter includes an outer catheter; an inner catheter positioned in the outer catheter, movable relative to the outer catheter in the longitudinal direction, and permitting a flexible medical elongate member to be inserted therethrough; an inflatable and contractible balloon constructed from a film member, and having one end portion and the other end portion fixed respectively to a distal portion of the outer catheter and a distal portion of the inner catheter, and projecting from a distal end of the outer catheter by an amount which varies according to the amount of movement of the inner catheter relative to the outer catheter; and position restriction means for restricting the position of a distal end of the medical elongate member, which is inserted through the inner catheter, relative to a distal end of the balloon. The construction of the balloon catheter helps ensure that a medical elongate member inserted through the inner catheter of the balloon catheter is inhibited or prevented from projecting in excess beyond the distal end of the balloon. Consequently, at a limit of movement of the medical elongate member in the distal direction, for example, the distal end of the medical elongate member is prevented from projecting in excess from the distal end of the balloon. 
     The position restriction means restricts the position of the distal end of the medical elongate member so that, at a limit of movement of the medical elongate member in the distal direction, the distal end of the medical elongate member is located in the vicinity of the distal end of the balloon. This helps ensure that the distal end of the medical elongate member, which is inserted through the inner catheter of a balloon catheter assembly, is reliably inhibited or prevented from projecting in excess from the distal end of the balloon. 
     The position restriction means can include: a contact member disposed on the proximal side of the inner catheter, and having a contact surface with which a part of the medical elongate member can make contact; and a connection mechanism by which the contact member and the inner catheter are connected to each other so that they can be brought close to (can move toward) and away from each other. 
     The connection mechanism can be configured to connect the contact member and the inner catheter to each other in such a manner that when the inner catheter and the contact member are moved in the same direction, the amount of movement of the contact member is less than (e.g., one-half) the amount of movement of the inner catheter. 
     The connection mechanism can include: at least a pair of pulleys arranged on the contact member along the longitudinal direction of the inner catheter; and a linear member or belt-like member which is wrapped around the pair of pulleys and to which the inner catheter and the outer catheter are fixed. Alternatively, the connection mechanism can include: at least one pinion gear rotatably supported on the contact member; an inside rack provided on the inner catheter and engaging with the pinion gear; and an outside rack provided on the outer catheter so as to face the inside rack, with the pinion gear therebetween, and engaging with the pinion gear. 
     The contact member can be constructed so that the position of the contact surface can be finely adjusted along the longitudinal direction of the catheter. This helps ensure that the position of the distal end of the medical elongate member relative to the distal end of the balloon is adjustable, for example in such a manner that the distal end of the medical elongate member is located a little on the proximal side relative to the distal end of the balloon, or so that the distal end of the medical elongate member is located a little on the distal side relative to the distal end of the balloon. 
     The position restriction means can also include a lock member for maintaining a state in which the contact member and the part of the medical elongate member, capable of making contact with the contact member, are in contact with each other. This helps reliably maintain the state in which the contact member and the medical elongate member are in contact with each other. Consequently, it is possible to relatively assuredly maintain a state in which, for example, the distal end of the balloon and the distal end of the medical elongate member are located at the same position with respect to the longitudinal direction of the catheter. 
     The balloon catheter can additionally be provided with projection preventive means for preventing the distal end of the inner catheter from projecting beyond the distal end of the outer catheter. This makes it possible to fairly securely prevent the distal end of the inner catheter from inadvertently projecting from the distal end of the outer catheter. 
     According to another aspect, a balloon catheter assembly comprises: a longitudinally extending outer catheter possessing a distal portion; an inner catheter positioned in the outer catheter and movable relative to the outer catheter in a longitudinal direction of the outer catheter, with the inner catheter possessing a distal portion; an inflatable and contractible balloon constructed from a film member having one end portion fixed to the distal portion of the outer catheter and an other end portion fixed to a distal portion of the inner catheter, with the balloon projecting distally beyond a distal-most end of the outer catheter by an amount which varies according to an amount of relative longitudinal movement between the inner catheter and the outer catheter; an elongated medical member positioned in the inner catheter of the balloon catheter and being movable relative to the inner catheter, the elongated medical member possessing a distal-most end; and position restriction means for restricting a position of the distal-most end of the medical elongate member positioned in the inner catheter relative to the distal end of the balloon. 
     According to a further aspect, a balloon catheter comprises: a longitudinally extending outer catheter possessing a distal portion; an inner catheter positioned in the outer catheter and axially movable relative to the outer catheter in a distal direction and proximal direction relative to the outer catheter, the inner catheter having a through hole configured to receive an elongated medical member, the inner catheter possessing a distal portion; an inflatable and contractible balloon constructed from a film member and projecting distally beyond a distal-most end of the outer catheter, the film possessing one end portion fixed to the distal portion of the outer catheter and an other end portion fixed to the distal portion of the inner catheter so that axial movement of the inner catheter in the distal direction relative to the outer catheter from a first position to a second position spaced apart from each other by a first axial distance causes the balloon to project further distally beyond the distal-most end of the outer catheter, an axial distance between a distal-most end of the balloon at the first position and the distal-most end of the balloon at the second position being a second distance less than the first distance; a contact portion configured to be contacted by a part of the elongated medical member when the elongated medical member is moved relative to the contact portion; and a connector connecting the contact portion and the inner catheter so that the axial movement of the inner catheter relative to the outer catheter over the first axial distance causes movement of the contact portion over an axial distance no greater than the second axial distance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIGS. 1(   a ) and  1 ( b ) are partial longitudinal cross-sectional views of a first embodiment of a balloon catheter assembly (including a balloon catheter) disclosed here, and sequentially illustrating states of use of the assembly including the balloon catheter. 
         FIG. 2  is a partial longitudinal cross-sectional view of the first embodiment of the balloon catheter assembly disclosed here illustrating a further state of use. 
         FIG. 3  is a longitudinal cross-sectional view showing a limit of movement in the distal direction of an inner catheter in the balloon catheter assembly shown in  FIG. 1 . 
         FIGS. 4(   a ) and  4 ( b ) are partial longitudinal cross-sectional views illustrating a second embodiment of a balloon catheter assembly (including a balloon catheter) disclosed here. 
         FIG. 5  is a partial longitudinal cross-sectional view illustrating a third embodiment of a balloon catheter assembly (including a balloon catheter) disclosed here. 
         FIGS. 6(   a ) and  6 ( b ) are partial longitudinal cross-sectional views illustrating a fourth embodiment of a balloon catheter assembly (including a balloon catheter) disclosed here. 
         FIG. 7  is a longitudinal sectional view illustrating a part of a balloon catheter assembly according to a fifth embodiment disclosed here. 
         FIG. 8  is a longitudinal sectional view illustrating a part of a balloon catheter assembly according to a sixth embodiment disclosed here. 
         FIG. 9  is a longitudinal sectional view illustrating a part of a balloon catheter assembly according to a seventh embodiment disclosed here. 
         FIGS. 10(   a )- 10 ( c ) are partial longitudinal cross-sectional views illustrating steps in use of the balloon catheter assembly shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     A first embodiment of a balloon catheter assembly, including a balloon catheter, disclosed here is illustrated in  FIGS. 1-3  which illustrate features and operational states of the assembly, and  FIG. 10  which depicts steps associated with use of the balloon catheter assembly. 
     For convenience of description, the right side in  FIGS. 1-3  and  10  (and in  FIGS. 4-9  as well) is referred to as the “proximal (side)” and the left side is referred to as the “distal (side).” 
     The balloon catheter assembly  1  shown in  FIGS. 1-3  is a balloon catheter assembly having particularly useful application in falloposcopic tuboplasty. The balloon catheter assembly  1  includes a balloon catheter  2 , and a medical elongate member  20  in the form of a falloposcope  20 . The falloposcope  20  is configured to be inserted through the balloon catheter  2 . Set forth below is a description of the configuration and construction of each of those components. 
     The falloposcope  20  includes a falloposcope body  201  which is elongate and flexible, and an enlarged-diameter section or enlarged member  202  which is positioned at an intermediate part of the falloposcope body  201 . The falloposcope body  201  has an image pick-up means having, for example, a CCD camera for picking up a pixel image, located on the distal side of the image pick-up means. The enlarged-diameter section  202  possesses an enlarged outer diameter which is larger in outer diameter than the adjoining portions of the falloposcope body  201 . 
     The balloon catheter  2  includes an outer catheter  3 , an inner catheter  4  positioned in the outer catheter  3 , and a balloon  5  connecting the distal ends of the outer catheter  3  and the inner catheter  4  to each other. 
     The outer catheter  3  has an outer catheter body  31  which is elongate and flexible, and an outer hub  32  which is fixed to a proximal portion of the outer catheter body  31 . 
     The outer catheter body  31  has a lumen (first lumen)  311  extending along the longitudinal direction (axial extent) of the outer catheter body  31 . The inner catheter body  41  of the inner catheter  4  is inserted into or positioned in the lumen  311 . The inner peripheral surface defining or surrounding the lumen  311  of the outer catheter body  31  may be a treated surface, for example a surface which has undergone a friction-reducing treatment, such as coating with a fluoro-polymer, to reduce frictional resistance between the inner peripheral surface and the outer peripheral surface of the inner catheter body  41  or the balloon  5 . 
     In addition, the outer catheter  3  is connected to a fluid supply source which supplies a working fluid for inflation and contraction of the balloon  5 . The working fluid from the supply source is supplied through the lumen  311  into the balloon  5 . In addition to the lumen  311 , a second lumen for supplying the working fluid may be formed in the outer catheter body  31  in parallel to the lumen  311 . 
     The outer hub  32  is fixed to the proximal portion of the outer catheter body  31 . The fixation method not specifically restricted. Possible fixation methods include, for example, a fusing method such as heat fusing (welding), high-frequency fusing, and ultrasonic fusing, an adhesion method such as adhesion with an adhesive or solvent, or the like. The outer catheter body  31  and the outer hub  32  may be integrally molded by, for example, injection molding or the like. The outer hub  32  is composed of a rectangular parallelepiped which is tetragonal in cross-section, and an inner cavity  321  of the outer hub  32  communicates with the lumen  311  of the outer catheter body  31 . The outer hub  32  may be composed of a hollow cylinder which is circular or elliptic in cross-section. In addition, a wall part (tube wall) of the outer hub  32  may be equipped with an insertion port into which a finger or the like is inserted at the time of gripping the inner catheter  4  and operating it to move. 
     The inner catheter  4  is a catheter permitting insertion of the falloposcope  20  therethrough, and includes an inner catheter body  41  and an inner hub  42  fixed to a proximal portion of the inner catheter body  41 . 
     The inner catheter body  41  is formed therein with a lumen  411  extending along the longitudinal direction (axial extent) of the inner catheter body  41 . The falloposcope body  201  of the falloposcope  20  is inserted through the lumen  411 . 
     The inner hub  42  is fixed to the proximal portion of the inner catheter body  41 . The fixation method for effecting this fixation can be, for example, one of the fixation methods mentioned above for fixing the outer catheter body  31  and the outer hub  32 . The inner catheter body  41  and the inner hub  42  may be integrally molded by, for example, injection molding or the like. The inner hub  42  is composed of a rectangular parallelepiped which is tetragonal in cross-section, and an inner cavity of the inner hub  42  communicates with the lumen  411  of the inner catheter body  41 . The inner hub  42  may be composed of a hollow cylinder which is circular or elliptic in cross-section. The falloposcope  20  passes through the inner cavity of the inner hub  42  to reach the lumen  411  of the inner catheter body  41 . In the configuration shown, the inner hub  42  is located in the inner cavity  321  of the outer hub  32 , independently of the position of the inner catheter  4  relative to the outer catheter  3 . 
     The inner catheter  4  thus configured can be axially moved relative to the outer catheter  3  in the longitudinal direction as seen from a comparison of  FIGS. 1 and 2 . In the balloon catheter assembly  1 , when the inner catheter  4  is axially moved relative to the outer catheter  3 , either the inner catheter  4  alone or both the inner catheter  4  and the falloposcope  20  together can be moved by an operation. 
     In addition, the inner hub  42  of the inner catheter  4  has an outside portion (outer diameter) greater than the inside diameter of the lumen  311  in the outer catheter body  31  of the outer catheter  3 . This ensures that when the inner catheter  4  is axially moved relative to the outer catheter  3  in the distal direction, the distal end  421  of the inner hub  42  abuts on the distal end wall  322  of the outer hub  32  of the outer catheter  3  as seen in  FIG. 3 . This restricts or limits the movement of the inner catheter  4  in the distal direction, so that the distal end  412  of the inner catheter body  41  of the inner catheter  4  is prevented from projecting distally beyond the distal end  312  of the outer catheter body  31  of the outer catheter  3 . Thus, the inner hub  42  also serves as a projection preventive means for preventing the distal end  412  of the inner catheter  4  from projecting distally beyond the distal end  312  of the outer catheter  3 . 
     The material or materials constituting the outer catheter body  31  and the inner catheter body  41  are not specifically restricted, and, for example, various thermosetting or thermoplastic resins such as polyolefin resins, polyamide resins, urethane resins, polyimide resins, etc. can be used. Specific examples of the usable material(s) include polyolefins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), etc., polyvinyl chloride, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc., polyurethane, polyamides, polyimides, polystyrene resins, fluoro-resins, and various thermoplastic elastomers based on styrene (polystyrene), polyolefin, polyvinyl chloride, polyurethane, polyester, polyamide, polybutadiene, fluoro-rubber or the like. Each of the outer catheter body  31  and the inner catheter body  41  may have a multilayer laminate structure composed of a plurality of materials. 
     The material or materials constituting the outer hub  32  and the inner hub  42  are not specifically restricted. Examples of the material(s) which can be used here include resin materials such as polyvinyl chloride, polyethylene, polypropylene, polycarbonate, polymethyl methacrylate, acrylonitrile-styrene-butadiene copolymer, etc. and various metallic materials. 
     The balloon  5  is constructed from a flexible film member. As shown in  FIGS. 1 to 3 , the balloon  5  is folded back at an intermediate portion thereof, has one end  51  fixed to the distal end  312  (distal portion) of the outer catheter  3 , and has the other end  52  fixed to the distal end  412  (distal portion) of the inner catheter  4 . This results in the balloon  5  having a bag-shaped form or configuration. The balloon  5  inflates upon supply of a working fluid and contracts upon removal of the working fluid by suction. The fixation method for fixing the balloon  5  to the distal end  312  (distal portion) of the outer catheter  3  and to the distal end  412  (distal portion) of the inner catheter  4  can be one of the fixation methods discussed above for fixing the outer catheter body  31  and the outer hub  32 . 
     In addition, the balloon  5  is ring-shaped in cross-section so that the falloposcope  20  can be inserted through a central portion of the balloon  5 . 
     As shown in  FIGS. 1(   a ) and  1 ( b ), when the inner catheter  4  is moved relative to the outer catheter  3 , the position of the folded-back portion (distal end  53 ) of the balloon  5  varies along the longitudinal direction of the catheter according to a movement amount L 1  of the inner catheter  4 , so that a projection amount L 2  of the balloon  5  beyond the distal end  312  of the outer catheter  3  also varies. 
     The balloon  5  is formed from one of various polymeric materials, particularly preferably a thermoplastic resin. In this case, preferably, the balloon  5  is formed from a material which is flexible as a whole but has a comparatively low percent elongation. Examples of the material which can be used to constitute the balloon  5  include: polyester resins or polyester elastomers such as polyethylene terephthalate, polybutylene terephthalate, etc.; olefin resins such as polyethylene, polypropylene, etc. which may be or may not be cross-linked by irradiation with electron rays; vinyl chloride resins; polyamide resins or polyamide elastomers such as nylon 11, nylon 12, nylon 610, etc.; polyurethane resins, ethylene-vinyl acetate copolymer which may be or may not be cross-linked by irradiation with electron rays; and polymer blends, polymer alloys and the like containing at least one of these polymers. 
     The balloon catheter  2  further has position restriction means  6  for restricting the position of the distal end  203  of the falloposcope body  201  of the falloposcope  20 , which is inserted through the inner catheter  4 , relative to the distal-most end  53  of the balloon  5 . Set forth below is a description of the position restriction means  6 . 
     As shown in  FIGS. 1(   a ),  1 ( b ) and  2 , the position restriction means  6  is composed of a contact member  7  disposed on the proximal side of the inner catheter, and a connection mechanism  8  by which the contact member  7  and the inner catheter  4  are connected to each other so that they can be brought close to and away from each other. In the illustrated embodiment, the connection mechanism is a connector that operatively connects the contact member  7  and the inner catheter  4  so that movement of the inner catheter  4  causes movement of the contact member  7 . 
     The contact member  7  is composed of a member which can be block-shaped. In addition, the contact member  7  includes a through-hole  71  penetrating the contact member  7  in the thickness direction (in the longitudinal direction of the catheter). The through-hole  71  permits the falloposcope body  201  of the falloposcope  20  to be inserted therethrough. When inserting the falloposcope  20  through the balloon catheter  2 , the falloposcope body  201  of the falloposcope  20  is first inserted through the through-hole  71  in the contact member  7  from the proximal side. Further, the falloposcope body  201  is inserted through the inner catheter  4 . In this manner, the inserting operation is carried out. 
     The proximal end face of the contact member  7  constitutes a contact surface  72  which the enlarged-diameter section  202  of the falloposcope  20  can contact. 
     The material constituting the contact member  7  is not specifically restricted. Examples of materials which can be used to fabricate the contact member  7  include the same material discussed above for the outer hub  32  or the inner hub  42 . 
     The connection mechanism  8  includes two pulley-wire sets, each of which includes a pair of pulleys  81   a  and  81   b , and a linear member or wire  82  wrapped around the pulley  81   a  and the pulley  81   b . The number of pulley-wire sets each including the pair of pulleys  81   a ,  81   b  and the wire  82  is not limited to two, and the number may be three or more, or may be only one. The example discussed in more detail below involves a structure in which two pulley-wire sets are arranged. In this balloon catheter  2 , the two pulley-wire sets are disposed correspondingly on both sides of the center axis of the inner catheter  4  (on the upper side and the lower side in  FIGS. 1 and 2 ). The two pulley-wire sets are the same in configuration, and, therefore, one of the two sets will be described below. The same description applies to the other set. 
     The pulley  81   a  and the pulley  81   b  are spaced from each other along the longitudinal direction of the catheter, and are rotatably supported on a pulley support section (arm)  73  of the contact member  7 . In addition, the pulley  81   a  is disposed on the inside of the outer hub  32  of the outer catheter  3 , whereas the pulley  81   b  is disposed on the outside of the outer hub  32 . 
     The wire  82  is, for example, a bundle (strand) of a multiplicity of metallic wires. The wire  82  is equipped, at intermediate parts thereof, with an outer hub fixing part  821  for fixing the outer hub  32  of the outer catheter  3 , and with an inner hub fixing part  822  for fixing the inner hub  42  of the inner catheter  4 . The outer hub fixing part  821  is a part by which an inner peripheral portion of the proximal end of the outer hub  32  of the outer catheter  3  and the wire  82  are connected and fixed to each other, while the inner hub fixing part  822  is a part by which an outer peripheral portion of the proximal end of the inner hub  42  of the inner catheter  4  and the wire  82  are connected and fixed to each other. The member wrapped around the pulleys  81   a  and  81   b  is not limited to the wire  82 , but may be a belt-shaped member such as a belt, for example. 
     With the position restriction means  6  configured as above, when the inner catheter  4  is gripped and is moved in the distal axial direction by the movement amount L 1 , the contact member  7  is also moved in the same direction attendantly on this movement as seen from a comparison of  FIGS. 1(   a ) and  1 ( b ). As above-mentioned, the inner catheter  4  and the contact member  7  are connected to each other by the connection mechanism  8  having the two sets of the pulleys  81   a ,  81   b  and the wire  82 . Therefore, the movement amount L 3  of the contact member  7  is equal to L 1 / 2 . 
     Because the balloon  5  is folded back at an intermediate portion thereof as above-mentioned, when the inner catheter  4  is moved in the distal axial direction by the movement amount L 1 , the projection amount L 2  is equal to L 1 / 2  as shown in  FIGS. 1(   a ) and  1 ( b ). Thus, when the inner catheter  4  is moved in the distal axial direction, the movement amount L 3  of the contact member  7  and the projection amount L 2  of the balloon  5  are equal to each other. This helps enable the operator to easily grasp or understand the projection amount L 2  of the balloon  5 . 
     In a first state (an initial state) shown in  FIG. 1(   a ), the balloon catheter assembly  1  is in such a state that a distal end face  204  of the enlarged-diameter section  202  of the falloposcope  20  is in abutment on the contact surface  72  of the contact member  7  of the balloon catheter assembly  1  so that the distal-most end  53  of the balloon  5  and the distal end  203  of the falloposcope  20  are located at the same position with respect to the longitudinal direction of the catheter. 
     Then, when the inner catheter  4  is moved by the movement amount L 1  in the distal direction starting from the state shown in  FIG. 1(   a ), a second state shown in  FIG. 1(   b ) is established. In this second state, the contact member  7  has been moved by the movement amount L 3 , which is one half the movement amount L 1 . And the balloon  5  project by the projection amount L 2 , which is one half the movement amount L 1 . 
     Furthermore, as shown in  FIG. 2 , starting from the state shown in  FIG. 1(   b ), the falloposcope  20  is moved in the distal direction until the enlarged-diameter section  202  abuts the contact member  7 . The amount of movement of the falloposcope  20  in this case is L 1 / 2 , naturally. In the third state shown in  FIG. 2 , therefore, the distal end  203  of the falloposcope  20  and the distal-most end  53  of the balloon  5  are located at the same position relative to one another with respect to the longitudinal direction of the catheter as in the state shown in  FIG. 1(   a ). 
     The balloon catheter is thus constructed so that the inner catheter  4  can axially move in the distal direction relative to the outer catheter  3  from a first position shown in  FIG. 1(   a ) to a second position shown in  FIG. 1(   b ) spaced apart from each other by a first axial distance L 1  and this movement causes the balloon  5  to project further distally beyond the distal-most end  312  of the outer catheter  3 . An axial distance between the distal-most end  53  of the balloon  5  at the first position shown in  FIG. 1(   a ) and the distal-most end  53  of the balloon  5  at the second position shown in  FIG. 1(   b ) is a second distance L 2  that is less than the first distance L 1 . In addition, the connection mechanism  8  (connector) connects the contact member  7  (contact portion) and the inner catheter  4  so that the axial movement of the inner catheter  4  relative to the outer catheter  3  over the first axial distance L 1  causes movement of the contact portion  7  over an axial distance no greater than the second axial distance L 2 . 
     Thus, the balloon catheter assembly  1  is constructed in such a way that at the limit of movement of the falloposcope  20  in the distal direction of the falloposcope  20 , the distal end  203  of the falloposcope  20  is located at the distal-most end  53  of the balloon  5 . Consequently, the distal end  203  of the falloposcope  20 , which is inserted through the inner catheter  4  of the balloon catheter assembly  1 , is securely prevented from projecting in excess from the distal-most end  53  of the balloon  5  (i.e., is prevented from projecting distally beyond the distal-most end  53  of the balloon  5 ). 
     If, by way of example, the distal end  203  of the falloposcope  20  projected in excess from the distal-most end  53  of the balloon  5 , the distal end  203  of the falloposcope  20  having thus projected may impinge on the fallopian tube to damage the fallopian tube. Or, on the contrary, the distal end  203  of the falloposcope  20  having impinged on the fallopian tube may be damaged (cracked). 
     The balloon catheter assembly  1  disclosed here can reliably inhibit or prevent this from occurring because the distal end  203  of the falloposcope  20  is prevented from projecting from the distal-most end  53  of the balloon  5 . 
     In addition, as above-mentioned, the distal end  412  of the inner catheter  4  is also prevented from projecting beyond the distal end  312  of the outer catheter  3 . This helps ensure that in the balloon catheter assembly  1 , none of the components, inclusive of the falloposcope  20 , projects beyond the balloon  5 . Therefore, such troubles as mentioned above can be more reliably prevented from occurring. 
     Now, an example of the method of using the balloon catheter assembly  1  will be described in detail below. 
     First, as shown in  FIG. 10(   a ), the balloon catheter assembly  1  is set in the first state previously shown and described in  FIG. 1(   a ). Keeping this state, the balloon catheter assembly  1  is inserted into a fallopian tube  30  to come into the vicinity of a stenosed part  301  of the fallopian tube  30 . This inserting operation can be performed under X-ray fluoroscopy, for example. In addition, during the inserting operation, the distal-most end  203  of the falloposcope  20  is prevented from projecting distally beyond the distal-most end  53  of the balloon  5 , as discussed above. Therefore, damage to the fallopian tube  30  by the distal end  203  is prevented from occurring. 
     Next, as shown in  FIG. 10(   b ), the inner catheter  4  is moved forward (advanced), to establish the second state previously shown and described in  FIG. 1(   b ). The balloon  5  is thus shifted or moved so that it projects distally farther beyond the distal end  312  of the outer catheter body  31  than in the  FIG. 10(   a ) state. Concurrently with this projecting operation, a working fluid is supplied into the balloon  5 . This reliably or assuredly sets the balloon  5  in the projecting state. Consequently, the stenosed part  301  can be enlarged by the balloon  5  in this projecting state. 
     Subsequently, as shown in  FIG. 10(   c ), the inner catheter  4  is moved backward (withdrawn), resulting in that the stenosed part  301  which has been enlarged can be observed through the distal end  203  of the falloposcope  20  located at the distal end  53  of the balloon  5 . 
     In a situation in which it is desired to insert the balloon catheter assembly  1  further into (deeper into) to the fallopian tube  30  starting from the state shown in  FIG. 10(   b ) without performing observation of the stenosed part  301  which has been enlarged, the falloposcope  20  is moved forward (advanced) into the third state previously shown and described in  FIG. 2 , whereby the inserting operation can be carried out. Then, in the third state, the inside of the fallopian tube  30  can be observed through the distal end  203  of the falloposcope  20  located at the distal end  53  of the balloon  5 . Also in the third state, the distal end  203  of the falloposcope  20  is inhibited or prevented from projecting beyond the distal end  53  of the balloon  5  and so the possibility of damaging the fallopian tube  30  by the distal end  203  is prevented from occurring. 
       FIGS. 4(   a ) and  4 ( b ) illustrate a second embodiment of the balloon catheter assembly (balloon catheter) disclosed here. The following description primarily focuses on differences between this embodiment and the earlier described embodiment. Features in this second embodiment which are similar to the first embodiment are identified by a common reference numeral, and a detailed description of such features is not repeated. 
     This second embodiment is the same as the first embodiment above, except for the configuration of the connection mechanism in the position restriction means. 
     As shown in  FIG. 4 , the position restriction means  6 A in this embodiment includes a connection mechanism  8 A having two pinion gear-rack sets, each including a pinion gear  83 , an inside rack  84  provided on the inner catheter  4  (provided on the outer surface of the inner hub  42 ), and an outside rack  85  provided on the outer catheter  3  (provided on the inner surface of the outer hub  32 ). The number of the pinion gear-rack sets each including the pinion gear  83 , the inside rack  84  and the outside rack  85  is not limited to two, as the number may be three or more, or may be only one. This embodiment disclosed by way of example here and discussed in more detail below includes a structure in which two pinion gear-rack sets are included. In this balloon catheter  2 , the pinion gear-rack sets are arranged correspondingly on both sides of the center axis of the inner catheter  4  (the upper side and the lower side in  FIG. 4 ). The two sets are the same as one another and so one of the two sets will be described below, it being understood that the description applies equally to the other set. 
     The pinion gear  83  is rotatably supported on a distal-side portion of the contact member  7 , through a pinion gear support section (arm)  74 . 
     The inside rack  84  is provided at the outer peripheral portion or surface of the inner hub  42  of the inner catheter  4 . The inside rack  84  engages the pinion gear  83 . 
     The outside rack  85  is provided at the inner peripheral portion or surface of the outer hub  32  of the outer catheter  3 . In addition, the outside rack  85  faces the inside rack  84 , with the pinion gear  83  therebetween. The outside rack  85  engages the pinion gear  83 , like the inside rack  84 . 
     Also in the position restriction means  6 A thus configured, like in the position restriction means  6  in the first embodiment above, movement of the inner catheter  4  in the distal direction by the movement amount L 1  results in that the movement amount L 3  of the contact member  7  is equal to L 1 / 2  (see  FIG. 4 ). The projection amount L 2  of the balloon  5  is equal to L 1 / 2  ( FIG. 4 ). Thus, when the inner catheter  4  is moved in the distal direction, the movement amount L 3  of the contact member  7  and the projection amount L 2  of the balloon  5  are equal to each other. This helps enable the operator to relatively easily grasp or understand the projection amount L 2  of the balloon  5 . 
     In a first state shown in  FIG. 4(   a ), the balloon catheter assembly  1  is in such a state that the distal end face  204  of the enlarged-diameter section  202  of the falloposcope  20  is in contact with the contact surface  72  of the contact member  7  of the balloon catheter assembly  1  so that the distal end  53  of the balloon  5  and the distal end  203  of the falloposcope  20  are located at the same position with respect to the longitudinal or axial direction of the catheter. 
     Then, in a second state shown in  FIG. 4(   b ) established when the inner catheter  4  is moved in the distal axial direction by the movement amount L 1  starting from the state shown in  FIG. 4(   a ), the contact member  7  moves by the movement amount L 3 , which is equal to one half the movement amount L 1 . The balloon  5  projects by the projection amount L 2 , which is equal to one half the movement amount L 1 . 
     Further, when the falloposcope  20  is moved in the distal direction until the enlarged-diameter section  202  abuts the contact member  7  starting from the state shown in  FIG. 4(   b ), the distal end  203  of the falloposcope  20  and the distal end  53  of the balloon  5  are once again located at the same position with respect to the longitudinal direction of the catheter. 
     Thus, also in the balloon catheter assembly  1  in this embodiment, it is possible to achieve a restriction such that at the limit of movement of the falloposcope  20  in the distal direction, the distal end  203  of the falloposcope  20  is located at the distal end  53  of the balloon  5 . This ensures that the distal end  203  of the falloposcope  20 , which is inserted through the inner catheter  4  of the balloon catheter assembly  1 , is securely prevented from projecting distally beyond the distal-most end  53  of the balloon  5 . 
       FIG. 5  illustrates a third embodiment of the balloon catheter assembly (balloon catheter) disclosed here. The following description primarily focuses on differences between this embodiment and the earlier described embodiments. Features in this third embodiment which are similar to features in the earlier embodiments are identified by a common reference numeral, and a detailed description of such features is not repeated. 
     This third embodiment is the same as the first embodiment above, except for the configuration of the contact member of the position restriction means. 
     As shown in  FIG. 5 , the position restriction means  6 B includes a contact member  7 B composed of a body section  75  and a bolt  76  which is in screw engagement (threaded engagement) with the body section  75  which is provided with pulley support sections  73 . 
     A through-hole  71  is provided in the bolt  76  and penetrates the bolt  76  in the longitudinal direction of the bolt. The through-hole  71  permits the falloposcope body  201  of the falloposcope  20  to be inserted therethrough. In addition, a top face (proximal end face) of a head section (screw head)  761  of the bolt  76  constitutes the contact surface  72  capable of making contact with the enlarged-diameter section  202  of the falloposcope  20 . The bolt  76  constitutes an adjustment mechanism permitting adjustment of the position of the contact surface in the longitudinal direction of the catheter. 
     In the contact member  7 B thus configured, when the bolt  76  is rotated in a predetermined direction relative to the body section  75 , the position of the contact surface  72  can be adjusted or moved toward the proximal side. When the bolt  76  is rotated in the reverse or opposite direction to the above-mentioned direction, the position of the contact surface  72  can be adjusted or moved toward the distal side. In this manner, the position of the contact surface  72  can be finely adjusted along the longitudinal direction of the catheter. This helps ensure that the position of the distal end  203  of the falloposcope  20  relative to the distal end  53  of the balloon  5  in the first state can be adjusted or varied, for example so that the distal-most end  203  of the falloposcope  20  is located a little on the proximal side relative to the distal-most end  53  of the balloon  5  such as shown in  FIG. 5 . In addition, the position can also be adjusted so that the distal-most end  203  of the falloposcope  20  is located a little on the distal side relative to the distal-most end  53  of the balloon  5 . 
       FIG. 6  illustrates a fourth embodiment of the balloon catheter assembly (balloon catheter) disclosed here. The following description primarily focuses on differences between this embodiment and the earlier described embodiments. Features in this fourth embodiment which are similar to features in the above-described embodiments are identified by common reference numerals, and a detailed description of such features is not repeated. 
     This fourth embodiment is the same as the first embodiment above, except that the position restriction means of the balloon catheter further includes a lock member. 
     As shown in  FIG. 6 , the position restriction means of the balloon catheter  2  further has a lock member  9  for maintaining a state in which the contact member  7  and the enlarged-diameter section  202  of the falloposcope  20  are in contact with each other. 
     The lock member  9  clamps the contact member  7  and the enlarged-diameter section  202  of the falloposcope  20  from the distal side and the proximal side. This helps makes it possible to securely maintain the state in which the contact member  7  and the enlarged-diameter section  202  of the falloposcope  20  are in contact with each other. Accordingly, it is possible to reliably maintain a state in which the distal end  53  of the balloon  5  and the distal end  203  of the falloposcope  20  are located at the same position with respect to the longitudinal direction of the catheter. 
     Starting from the state shown in  FIG. 6(   a ) and performing an operation of moving the lock member  9  in the distal direction, the contact member  7  and the falloposcope  20  move together as seen from a comparison of  FIGS. 6(   a ) and  6 ( b ). Therefore, operationality of the balloon catheter  2  is enhanced, as compared with the case where the contact member  7  and the falloposcope  20  are operated separately. In addition, during the operation of moving the lock member  9 , the state in which the distal end  53  of the balloon  5  and the distal end  203  of the falloposcope  20  are located at the same position with respect to the longitudinal or axial direction of the catheter is constantly maintained. Consequently, the balloon  5  can be moved while observing the inside of the fallopian tube  30  through the falloposcope  20 . 
       FIG. 7  illustrates a fifth embodiment of the balloon catheter assembly (balloon catheter) disclosed here. The following description primarily focuses on differences between this embodiment and the earlier described embodiments. Features in this fifth embodiment which are similar to features in the above-described embodiments are identified by common reference numerals, and a detailed description of such features is not repeated. 
     This fifth embodiment is the same as the first embodiment above, except for a difference in the configuration of the enlarged-diameter section of the falloposcope. 
     As shown in  FIG. 7 , the falloposcope  20 A includes an enlarged-diameter section or enlarged member  202 A which is composed of a body separate from the falloposcope body  201 . The enlarged-diameter section  202 A is composed of a body section  205  and a bolt  206  in screw engagement with the body section  205 . 
     The body section  205  is annular-shaped or ring-shaped. The inside diameter of the body section  205  is greater than the outside diameter of the falloposcope body  201 . 
     The bolt  206  is in screw engagement with a wall part of the body section  205 . In addition, a leg section (screw section)  206   a  of the bolt  206  can contact and clamp the falloposcope body  201  between the inner peripheral portion  205   a  of the body section  205  and the leg section  206   a  as shown in  FIG. 7 . 
     When the bolt  206  is rotated in a predetermined direction relative to the body section  205 , the bolt  206  is loosened so that the leg section  206   a  moves away from the falloposcope body  201 . This permits the enlarged-diameter section  202 A as a whole to move along the longitudinal direction of the falloposcope body  201 , so that the position of the enlarged-diameter section  202 A can be finely adjusted. Then, with the bolt  206  in the finely adjusted position and rotated in the reverse or opposite direction to the above-mentioned direction, movement of the enlarged-diameter section  202 A is restricted. This helps ensure that the position of the distal end  203  of the falloposcope  20 A relative to the distal end  53  of the balloon  5  in the first state can be adjusted so that, for example, the distal-most end  203  of the falloposcope  20 A is located a little on the proximal side relative to the distal-most end  53  of the balloon  5 . In addition, the position can also be adjusted so that the distal-most end  203  of the falloposcope  20 A is located a little on the distal side relative to the distal-most end  53  of the balloon  5 . Consequently, the position of the distal end  203  of the falloposcope  20 A relative to the distal end  53  of the balloon  5  can be finely adjusted according to the operator&#39;s preference or the nature of the intended procedure. 
       FIG. 8  illustrates a sixth embodiment of the balloon catheter assembly (balloon catheter) disclosed here. The following description primarily focuses on differences between this embodiment and the earlier described embodiments. Features in this sixth embodiment which are similar to features in the above-described embodiments are identified by common reference numerals, and a detailed description of such features is not repeated. 
     This sixth embodiment is the same as the fifth embodiment above, except for a difference in the configuration of the enlarged-diameter section of the falloposcope. 
     As shown in  FIG. 8 , the falloposcope  20 B includes an enlarged-diameter section or enlarged member  202 B connected to the falloposcope body  201  through a connection member  207 . 
     The connection member  207 , is cylindrical in outer shape and is fixed to the falloposcope body  201 . The outer peripheral portion of the connection member  207  includes a male screw  207   a.    
     The enlarged-diameter section  202 B is annular-shaped or ring-shaped. The inner peripheral surface of the through hole in the enlarged-diameter section  202 B is screw-threaded to form a female screw  208  for threaded engagement with the male screw  207   a  of the connection member  207 . 
     In the falloposcope  20 B thus configured, when the enlarged-diameter section  202 B is rotated in a predetermined direction relative to the connection member  207 , the enlarged-diameter section  202 B is moved toward the proximal side or in the proximal direction. In addition, when the enlarged-diameter section  202 B is rotated in the reverse or opposite direction to the above-mentioned direction, the enlarged-diameter section  202 B moves toward the distal side. Thus, the position of the enlarged-diameter section  202 B can be finely adjusted in the longitudinal or axial direction of the catheter. This helps ensure that the position of the distal end  203  of the falloposcope  20 B relative to the distal-most end  53  of the balloon  5  in the first state can be adjusted so that, for example the distal end  203  of the falloposcope  20 B is located a little on the proximal side relative to the distal-most end  53  of the balloon  5 . The position can also be adjusted so that the distal-most end  203  of the falloposcope  20 B is located a little on the distal side relative to the distal-most end  53  of the balloon  5 . Consequently, the position of the distal-most end  203  of the falloposcope  20 B relative to the distal-most end  53  of the balloon  5  can be finely adjusted according to the operator&#39;s preference or the nature of the intended procedure. 
       FIG. 9  illustrates a seventh embodiment of the balloon catheter assembly (balloon catheter) disclosed here. The following description primarily focuses on differences between this embodiment and the earlier described embodiments. Features in this seventh embodiment which are similar to features in the above-described embodiments are identified by common reference numerals, and a detailed description of such features is not repeated. 
     This embodiment is the same as the fifth embodiment above, except for a difference in the configuration of the enlarged-diameter section of the falloposcope. 
     As shown in  FIG. 9 , the falloposcope  20 C includes an enlarged-diameter section or enlarged member  202 C composed of a body section  209 , a pin  210  fitted in a through hole in the body section  209 , and a coil spring  211  also positioned in the through hole of the body section and biasing the pin  210 . 
     The body section  209  is ring-shaped or annular-shaped. The inside diameter of the through hole in the body section  209  is greater than the outside diameter of the falloposcope body  201 . 
     The pin  210  is fitted in the wall part of the body section  209  in such a manner as to be movable in a direction orthogonal to the axial direction of the body section  209 . In addition, a flange section  210   a  of the pin  210  can clamp the falloposcope body  201  between an inner peripheral portion  209   a  of the through hole in the body section  209  and the flange section  210   a  of the pin  210  as shown in  FIG. 9 . 
     The coil spring  211  biases the pin  210  in a direction such that the flange section  210   a  clamps the falloposcope body  201  between the inner peripheral portion  209   a  of the body section  209  and the flange section  210   a  of the pin  210 . This helps ensure that the falloposcope body  201  is clamped assuredly. Movement of the enlarged-diameter section  202 C along the longitudinal or axial direction of the falloposcope body  201  is thus restricted. 
     In the falloposcope  20 C thus configured, when the pin  210  is depressed against the biasing force of the coil spring  211 , the clamping force exerted on the falloposcope body  201  is released. As a result, the enlarged-diameter section  202 C as a whole can be moved along the longitudinal direction of the falloposcope body  201 , so that the position of the enlarged-diameter section  202 C can be finely adjusted. Then, when the depressing force on the pin  210  in the finely adjusted position is released, movement of the enlarged-diameter section  202 C is restricted as above-mentioned. This helps ensure that the position of the distal end  203  of the falloposcope  20 C relative to the distal end  53  of the balloon  5  in the first state can be adjusted so that, for example, the distal end  203  of the falloposcope  20 C is located a little on the proximal side relative to the distal end  53  of the balloon  5 . In addition, the position can also be adjusted so that, on the contrary to the above, the distal end  203  of the falloposcope  20 C is located a little on the distal side relative to the distal end  53  of the balloon  5 . Consequently, the position of the distal end  203  of the falloposcope  20 C relative to the distal end  53  of the balloon  5  can be finely adjusted according to the operator&#39;s preference or the nature of the intended procedure. 
     While the balloon catheter and the balloon catheter assembly disclosed here have been described above based on embodiments shown in the drawings, the invention is not limited to the above embodiments. Components of the balloon catheter and the balloon catheter assembly can be replaced by alternatives that can exhibit the same or similar functions. And other features may be added. 
     In addition, the balloon catheter and the balloon catheter assembly may combine arbitrary two or more configurations (characteristic features) of the above-described embodiments. For example, the embodiments shown in  FIGS. 1-4  can be used with the adjustment mechanisms shown in FIGS.  5  and  7 - 9 , and the embodiment shown in  FIG. 6  can be used with the connection mechanism  8 A shown in  FIG. 4 . 
     The balloon catheter assembly disclosed here may be an assembly in which the contact member disposed on the proximal side of the inner catheter and a medical elongate member are inseparably integrated with each other. 
     In addition, the balloon catheter may be provided with graduations for indicating the amount of movement when the inner catheter is operated to move. Or, alternatively, a graduation member having the function as graduations may be provided. The graduation member is not specifically restricted; for example, a bellows-like member can be preferably used. 
     While the falloposcope has been mentioned in the above-described embodiments as an example of the medical elongate member to be inserted through the balloon catheter, this is not limitative. Other examples of the medical elongate member include other kinds of endoscopes, catheters, and guide wires. 
     The balloon catheter disclosed here includes: an outer catheter; an inner catheter inserted in the outer catheter, capable of moving relative to the outer catheter in the longitudinal direction thereof, and permitting a flexible medical elongate member to be inserted therethrough; an inflatable and contractible balloon constructed from a film member, having one end portion and the other end portion fixed respectively to a distal portion of the outer catheter and a distal portion of the inner catheter, and projecting from the distal end of the outer catheter by an amount which varies according to the amount of movement of the inner catheter relative to the outer catheter; and position restriction means for restricting the position of the distal end of the medical elongate member, which is inserted through the inner catheter, relative to the distal end of the balloon. Therefore, the medical elongate member inserted through the inner catheter of the balloon catheter can be prevented from projecting beyond or excessively beyond the distal end of the balloon. Accordingly, the balloon catheter disclosed here has industrial applicability. 
     The detailed description above describes features and aspects of embodiments, disclosed by way of example, of a balloon catheter and a balloon catheter assembly. The invention is not limited, however, to the precise embodiments and variations described and illustrated. Various changes, modifications and equivalents could be effected by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims. It is expressly intended that all such changes, modifications and equivalents which fall within the scope of the claims are embraced by the claims.