Patent Publication Number: US-2023141641-A1

Title: Balloon catheter

Description:
TECHNICAL FIELD 
     This disclosure relates to a balloon catheter. 
     BACKGROUND 
     As shown in JP 5913739 B2, in recent years, treatment using a balloon catheter has been performed. Balloon catheters are used to cauterize myocardial tissue with heated liquid in the balloon, for example, in the treatment of arrhythmias.  FIG.  9    illustrates a catheter system  100  to which a conventional balloon catheter  110  is applied. 
     The catheter system  100  illustrated in  FIG.  9    includes a balloon catheter  110 , a stirring device  120  that stirs liquid in the balloon catheter  110 , and a heating device  130  that heats the liquid. The balloon catheter  110  includes a catheter shaft  111  in which a liquid feeding path is formed, a balloon  112  attached to a distal end portion of the catheter shaft  111 , and a syringe  113  that supplies and discharges liquid to and from the liquid feeding path of the catheter shaft  111  and the balloon  112 . The syringe  113  and the stirring device  120  are connected to the catheter shaft  111  via a three-way stopcock  140  and a flexible tube  145 . By operating the three-way stopcock  140 , one of the syringe  113  and the stirring device  120  can communicate with the liquid feeding path of the catheter shaft  111 . 
     Such an operation of the balloon catheter  110  is very complicated because it is necessary to operate the three-way stopcock  140  and the like while holding the catheter shaft  111  inserted into the body of the patient. Therefore, operation of the balloon catheter  110  requires a plurality of personnel. For example, as indicated by broken lines in  FIG.  9   , while a person holds the catheter shaft  111  with his/her both hands A1 and A2, another person operates the three-way stopcock  140  or the like with both hands B1 and B2. 
     Meanwhile, it is required to improve the operability of the balloon catheter so that the number of personnel required for operating the balloon catheter can be reduced. 
     It could therefore be helpful to provide a balloon catheter with improved operability. 
     SUMMARY 
     We thus provide: 
     A balloon catheter comprises: a housing; a catheter shaft having a proximal end portion disposed in the housing and forming a liquid feeding path communicating with an inside of a balloon attached to a distal end portion of the catheter shaft; a supply-discharge line connection portion which has an internal space communicating with the liquid feeding path, and to which a supply-discharge line that supplies and discharges liquid to and from the liquid feeding path through the internal space can be connected; and a stopcock capable of closing the internal space of the supply-discharge line connection portion, in which a position of the supply-discharge line connection portion with respect to the housing is fixed. 
     The balloon catheter may further comprise: the supply-discharge line connected to the supply-discharge line connection portion; and a supply-discharge device that is connected to the supply-discharge line to supply and discharge liquid to and from the supply-discharge line, and the supply-discharge line may include a soft tube having a length of 200 mm or more. 
     The balloon catheter may further comprise a stirring line connection portion which has an internal space communicating with the liquid feeding path, and to which a stirring line that sucks and discharges liquid from and into the liquid feeding path through the internal space of the stirring line connection portion to stir liquid in the balloon can be connected, and a connection portion between the internal space of the stirring line connection portion and the liquid feeding path may be located closer to the distal end portion of the catheter shaft than a connection portion between the internal space of the supply-discharge line connection portion and the liquid feeding path. 
     The stirring line connection portion may be fixed to the housing. 
     The catheter shaft may include an inner cylinder shaft to which a distal end of the balloon is fixed and an outer cylinder shaft to which a proximal end of the balloon is fixed, the outer cylinder shaft having a lumen into which the inner cylinder shaft is inserted to form the liquid feeding path between the outer cylinder shaft and the inner cylinder shaft, and the housing may be provided with an operation unit that extends the balloon by moving the inner cylinder shaft relative to the outer cylinder shaft along a first direction in which the proximal end portion of the catheter shaft extends. 
     The housing may include a narrow portion narrowed in a direction intersecting a first direction in which the proximal end portion of the catheter shaft extends, a first gripping portion connected to the narrow portion from one side in the first direction, and a second gripping portion connected to the narrow portion from the other side in the first direction. 
     The catheter shaft may include an inner cylinder shaft to which a distal end of the balloon is fixed and an outer cylinder shaft to which a proximal end of the balloon is fixed, the outer cylinder shaft having a lumen into which the inner cylinder shaft is inserted to form the liquid feeding path between the outer cylinder shaft and the inner cylinder shaft, a maximum outer radius of the first gripping portion about an axis extending along the first direction may be larger than a maximum outer radius of the second gripping portion about an axis extending along the first direction, and the first gripping portion may be provided with an operation unit that moves the inner cylinder shaft relative to the outer cylinder shaft along the first direction to extend the balloon. 
     Alternatively, a balloon catheter comprises: a housing; and a catheter shaft having a proximal end portion disposed in the housing and forming a liquid feeding path communicating with an inside of a balloon attached to a distal end portion, in which the housing includes a narrow portion narrowed in a direction intersecting a first direction in which the proximal end portion of the catheter shaft extends, a first gripping portion connected to the narrow portion from one side in the first direction, and a second gripping portion connected to the narrow portion from the other side in the first direction. 
     Alternatively, a balloon catheter comprises: a housing; 
     a catheter shaft having a proximal end portion disposed in the housing and forming a liquid feeding path communicating with an inside of a balloon attached to a distal end portion of the catheter shaft;   a supply-discharge line connection portion which has an internal space communicating with the liquid feeding path, and to which a supply-discharge line that supplies and discharges liquid to and from the liquid feeding path through the internal space of the supply-discharge line connection portion can be connected; and   a stirring line connection portion which has an internal space communicating with the liquid feeding path, and to which a stirring line that sucks and discharges liquid from and into the liquid feeding path through the internal space of the stirring line connection portion to stir liquid in the balloon can be connected,   in which a connection portion between the internal space of the stirring line connection portion and the liquid feeding path is located closer to the distal end portion of the catheter shaft than a connection portion between the internal space of the supply-discharge line connection portion and the liquid feeding path.   

     It is thus possible to provide a balloon catheter with improved operability. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a view showing an example, and illustrates an overall configuration of a catheter system to which a balloon catheter is applied. 
         FIG.  2    is a side view illustrating a proximal end portion of the balloon catheter illustrated in  FIG.  1   . 
         FIG.  3    is a cross-sectional view schematically illustrating a catheter shaft and a balloon. 
         FIG.  4    is a cross-sectional view schematically illustrating the catheter shaft and the balloon. 
         FIG.  5    is a diagram illustrating a method of operating an operation unit. 
         FIG.  6    is a view illustrating a partial cross-sectional view of a housing taken along line I-I of  FIG.  1    together with a movement restricting protrusion of an operation unit. 
         FIG.  7    is a view illustrating a method of operating a stopcock. 
         FIG.  8    is a front view of the housing as viewed from a distal end side of the housing. 
         FIG.  9    is a diagram illustrating an overall configuration of a conventional catheter system. 
     
    
    
     REFERENCE SIGNS LIST 
       1  catheter system  1 ,  10  balloon catheter  15  balloon  20  catheter shaft  22  inner cylinder shaft  24  outer cylinder shaft  30  supply-discharge line connection portion  31  internal space of supply-discharge line connection portion  35  stopcock  40  stirring line connection portion  41  internal space of stirring line connection portion  50  operation unit  55  housing  57  narrow portion  58  first gripping portion  59  second gripping portion  60  stirring line  65  stirring device  70  heating electrode  71  lead wire  75  heating device 
     DETAILED DESCRIPTION 
       FIG.  1    shows a balloon catheter according to an example.  FIG.  1    schematically illustrates an overall configuration of a catheter system  1  to which a balloon catheter  10  in the example is applied. The balloon catheter  10  in the example is devised to improve operability. 
     The catheter system  1  illustrated in  FIG.  1    comprises the balloon catheter (“catheter”)  10  to and from which liquid is supplied and discharged, a stirring line  60  and a stirring device  65  that stirs the liquid in the catheter  10 , and a heating device  75  that heats the liquid in the catheter  10 . 
     The catheter  10  comprises a catheter shaft  20  having a distal end to which a balloon  15  is attached, a supply-discharge line connection portion  30 , a stopcock  35 , a stirring line connection portion  40 , an operation unit  50  for extending the balloon  15 , and a housing  55  that accommodates a proximal end portion of the catheter shaft  20 . In the illustrated example, the catheter  10  further comprises a supply-discharge line  36  connected to the supply-discharge line connection portion  30 , a supply-discharge device  38  connected to the supply-discharge line  36 , and a heating electrode  70  electrically connected to the heating device  75  to heat the liquid in the balloon  15 . 
     The terms “distal ends” and “distal end portions” used with respect to the balloon  15 , the catheter shaft  20  (including its inner cylinder shaft  22  and outer cylinder shaft  24  to be described later), the operation unit  50 , and the housing  55  (including each portion of the housing  55 ) respectively mean end portions on the side close to the distal end of the catheter  10  extended in a straight line unless otherwise specified. In addition, the terms “proximal ends” and “proximal end portions” used with respect to the balloon  15 , the catheter shaft  20 , the operation unit  50 , and the housing  55  respectively mean end portions opposite to the distal ends of the balloon  15 , the catheter shaft  20 , the operation unit  50 , and the housing  55  unless otherwise specified. 
       FIG.  2    illustrates a side view of the proximal end portion of the catheter shaft  20 . Further,  FIGS.  3  and  4    are cross-sectional views schematically illustrating the structure of the catheter shaft  20 .  FIG.  3    illustrates a cross section of the catheter shaft  20  with the balloon  15  in a liquid inflatable state in which the balloon  15  is inflatable with liquid, and  FIG.  4    illustrates a cross section of the catheter shaft  20  with the balloon  15  in an extended state. 
     As illustrated in  FIGS.  3  and  4   , the catheter shaft  20  is formed with a liquid feeding path  21  for feeding liquid to the balloon  15 . The liquid feeding path  21  communicates with the inside of the balloon  15 . In the illustrated example, as illustrated in  FIGS.  2  to  4   , the catheter shaft  20  includes an inner cylinder shaft  22  and an outer cylinder shaft  24 . The inner cylinder shaft  22  is inserted into the lumen of the outer cylinder shaft  24 . The liquid feeding path  21  is formed between the inner cylinder shaft  22  and the outer cylinder shaft  24 . A guide wire (not illustrated) for guiding the catheter shaft  20  in the body of the patient is inserted into the lumen of the inner cylinder shaft  22 . 
     The outer cylinder shaft  24  is not movable with respect to the inside of the housing  55 . The inner cylinder shaft  22  is movable relative to the outer cylinder shaft  24  along the longitudinal direction of the catheter shaft  20 . In the illustrated example, the inner cylinder shaft  22  is movable between two positions (balloon inflatable position illustrated in  FIG.  3    and balloon extension position illustrated in  FIG.  4   ) with reference to the outer cylinder shaft  24 . The operation unit  50  for moving the inner cylinder shaft  22  relative to the outer cylinder shaft  24  is fixed to the inner cylinder shaft  22 . 
     The length of the catheter shaft  20  is preferably 0.5 to 2 m from the viewpoint of allowing the balloon  15  to reach the myocardial tissue. Further, the diameter of the catheter shaft  20  is preferably 3 to 5 mm from the viewpoint of insertion into a blood vessel. The material of the catheter shaft  20  is preferably a flexible material having excellent antithrombogenicity, and examples thereof include a fluororesin, a polyamide resin, a polyurethane resin, and a polyimide resin, but are not limited thereto. 
     The internal space of the balloon  15  communicates with the liquid feeding path  21 . In the example illustrated in  FIGS.  3  and  4   , the distal end of the balloon  15  is fixed to the distal end of the inner cylinder shaft  22 . Further, the proximal end of the balloon  15  is fixed to the distal end of the outer cylinder shaft  24 . Then, by moving the inner cylinder shaft  22  relative to the outer cylinder shaft  24  along the longitudinal direction of the catheter shaft  20 , the balloon  15  can be extended in the direction of the relative movement between the inner cylinder shaft  22  and the outer cylinder shaft  24 . 
     The diameter of the balloon  15  is preferably  20  to 40 mm from the viewpoint of being able to closely contact the site where the arrhythmia occurs. Further, the balloon  15  preferably has a spherical shape. Further, the thickness of the balloon  15  is preferably 20 to 100 µm. As the material of the balloon  15 , a stretchable material excellent in antithrombogenicity is preferable, and a polyurethane-based polymer material is more preferable. Examples of the polyurethane-based polymer material include thermoplastic polyether urethane, polyether polyurethane urea, fluorine polyether urethane urea, polyether polyurethane urea resin, and polyether polyurethane urea amide. 
     As illustrated in  FIGS.  2  to  4   , the operation unit  50  is fixed to the inner cylinder shaft  22 . In addition, the operation unit  50  is movable relative to the housing  55  in a first direction D1 along the proximal end portion of the catheter shaft  20 . Therefore, the operation unit  50  is movable together with the inner cylinder shaft  22  relative to the housing  55  and the outer cylinder shaft  24  in the first direction D1. In the illustrated example, the proximal end portion of the inner cylinder shaft  22  extends from the proximal end of the outer cylinder shaft  24 , and a proximal end portion  51  of the operation unit  50  is connected to the proximal end portion of the inner cylinder shaft  22 . A distal end portion  52  of the operation unit  50  is exposed to the outside of the housing  55  through an operation unit opening  55   a  formed in the housing  55 , and the operation unit  50  can be operated from the outside of the housing  55 . As illustrated in  FIG.  5   , such an operation unit  50  can be operated with the same hand H 2  as the hand H 2  gripping the housing  55 . 
       FIG.  6    is a cross-sectional view illustrating the housing  55  and the proximal end portion of the operation unit  50 . In the illustrated example, as illustrated in  FIG.  6   , the proximal end portion  51  of the operation unit  50  is provided with a movement restricting protrusion  53  that protrudes in a second direction D2 intersecting the first direction D1 that is the moving direction of the operation unit  50 . The relative movement of the operation unit  50  relative to the housing  55  is restricted by engaging the movement restricting protrusion  53  with any one of a plurality of movement restricting recesses  56  provided along the first direction D1 on the inner wall of the housing  55 . This may maintain the balloon  15  at a desired length along the longitudinal direction of the catheter shaft  20 . 
     The engagement between the movement restricting protrusion  53  and the movement restricting recess  56  can be released by the proximal end portion  51  of the operation unit  50  being elastically deformed in the second direction D2. In the illustrated example, since each movement restricting recess  56  is delimited by inclined surfaces of the side wall portions  56   b  facing one another in the first direction D1, when a force in the first direction D1 is applied to the operation unit  50  in a state where the movement restricting protrusion  53  and the movement restricting recess  56  are engaged, a force in the second direction D2 is applied from the side wall portion  56   a  to the movement restricting protrusion  53 , and the proximal end portion  51  of the operation unit  50  is elastically deformed in the second direction D2. As a result, the movement restricting protrusion  53  moves in the second direction D2, and the engagement between the movement restricting protrusion  53  and the movement restricting recess  56  is released. As a matter of course, the method of releasing the engagement between the movement restricting protrusion  53  and the movement restricting recess  56  is not limited thereto. The engagement between the movement restricting protrusion  53  and the movement restricting recess  56  may be released, for example, by the housing  55  being elastically deformed in the second direction D2. 
     The supply-discharge line connection portion  30  is formed in a tubular shape and has an internal space  31  communicating with the liquid feeding path  21  (see  FIGS.  3  and  4   ). The liquid is supplied to and discharged from the liquid feeding path  21  through the internal space  31 . In the illustrated example, the supply-discharge line connection portion  30  is connected to the proximal end portion of the outer cylinder shaft  24 , and the position thereof with respect to the housing  55  is fixed. 
     As illustrated in  FIG.  1   , one end of the supply-discharge line  36  is connected to the supply-discharge device  38 , and the other end thereof is connected to the supply-discharge line connection portion  30 . The supply-discharge line  36  supplies and discharges liquid to and from the liquid feeding path  21  through the internal space  31  of the supply-discharge line connection portion  30 . In the illustrated example, the supply-discharge line  36  includes a soft tube having a length of 200 mm or more. Since the supply-discharge line  36  includes a soft tube having a sufficient length, as illustrated in  FIG.  7   , it is possible to curve the supply-discharge line  36  to operate the stopcock  35  while gripping the supply-discharge device  38  in a state where the supply-discharge device  38  is connected to the catheter shaft  20  via the supply-discharge line  36  and the supply-discharge line connection portion  30 . As the material of the supply-discharge line  36 , for example, polyvinyl chloride, polyurethane, silicon, polyamide or the like can be employed. 
     The supply-discharge device  38  supplies and discharges liquid to and from the supply-discharge line  36 . In the illustrated example, the supply-discharge device  38  is a syringe, but is not limited thereto. In the example illustrated in  FIG.  1   , the supply-discharge device  38  is provided with a ring/rings  39  through which a person who operates the supply-discharge device  38  passes his/her finger/fingers. This makes it easy to operate the stopcock  35  and the like while gripping the supply-discharge device  38 . As the liquid supplied and discharged by the supply-discharge device  38 , a contrast medium or a contrast medium diluted with physiological saline is preferable so that the balloon  15  inflated with the liquid can be confirmed by an X-ray fluoroscopic image. 
     The supply-discharge line  36  and the supply-discharge device  38  may be included in the catheter system  1  and may not be included in the balloon catheter  10 . 
     The stopcock  35  is provided in the supply-discharge line connection portion  30 . More specifically, a part of the stopcock  35  is arranged in the internal space  31  of the supply-discharge line connection portion  30 , and the internal space  31  of the supply-discharge line connection portion  30  can be closed by rotating the stopcock  35  relative to the supply-discharge line connection portion  30  and arranging the stopcock  35  in a predetermined direction. In the illustrated example, the stopcock  35  is rotatable between a closed position indicated by a solid line in  FIG.  2    and an open position indicated by a broken line in  FIG.  2   . When the stopcock  35  is disposed at the closed position, the internal space  31  of the supply-discharge line connection portion  30  is closed, and the communication between the supply-discharge line  36  and the liquid feeding path  21  is blocked. When the stopcock  35  is disposed at the open position, the internal space  31  of the supply-discharge line connection portion  30  is opened, and the supply-discharge line  36  and the liquid feeding path  21  communicate with each other. 
     As described above, the position of the supply-discharge line connection portion  30  with respect to the housing  55  is fixed. This improves the operability of the stopcock  35 . Specifically, first, as illustrated in  FIG.  7   , the catheter shaft  20  and the supply-discharge line connection portion  30  can be simultaneously retained by retaining the housing  55 . In other words, the supply-discharge line connection portion  30  can be retained by a hand holding the catheter shaft  20 . Therefore, it is possible to retain the catheter shaft  20  and the supply-discharge line connection portion  30  by gripping the housing  55  with one hand and operate the stopcock  35  with the other hand. That is, it is possible that a person who operates the catheter shaft  20  operates the stopcock  35  while retaining the catheter shaft  20 . 
     The stirring line connection portion  40  is formed in a tubular shape and has an internal space  41  communicating with the liquid feeding path  21  (see  FIGS.  3  and  4   ). The stirring line connection portion  40  is connected with a stirring line  60  that sucks and discharges liquid from and into the liquid feeding path  21  through the internal space  41  of the stirring line connection portion  40 . When the stirring line  60  is connected and the liquid is sucked and discharged from and into the liquid feeding path  21 , the liquid in the balloon  15  vibrates and is stirred. By stirring the liquid in the balloon  15 , the surface temperature of the balloon  15  can be made uniform, and the diseased part can be uniformly cauterized. 
     The stirring line  60  is connected to the stirring device  65  to suck and discharge the liquid from and into the liquid feeding path  21 . The stirring device  65  periodically sucks and discharges the liquid from and into the internal space of the stirring line  60 . The stirring device  65  is preferably a device that repeats suction and discharge of liquid 1 to 5 times per 1 second, and preferably includes a pump selected from the group consisting of a roller pump, a diaphragm pump, a bellows pump, a vane pump, a centrifugal pump, and a pump including a combination of a piston and a cylinder. 
     The stirring line connection portion  40  is connected to the proximal end portion of the outer cylinder shaft  24 . In the illustrated example, the stirring line connection portion  40  is fixed to the housing  55 . Accordingly, by holding the housing  55 , the stirring line connection portion  40  and the stirring line  60  can be held together with the catheter shaft  20 . 
     In the illustrated example, as illustrated in  FIG.  2   , the stirring line connection portion  40  is provided closer to the distal end portion of the catheter shaft  20  than the supply-discharge line connection portion  30 . In other words, as illustrated in  FIGS.  3  and  4   , the connection portion between the internal space  41  of the stirring line connection portion  40  and the liquid feeding path  21  is located closer to the distal end portion of the catheter shaft  20  than the connection portion between the internal space  31  of the supply-discharge line connection portion  30  and the liquid feeding path  21 . As a result, it is possible to control stirring of the liquid and supply and discharge of the liquid independently. Specifically, even during supply of the liquid from the supply-discharge line  36  to the liquid feeding path  21  and discharge of the liquid from the liquid feeding path  21  to the supply-discharge line  36 , the liquid can be sucked and discharged from and into the liquid feeding path  21  through the internal space  41  of the stirring line connection portion  40  to stir the liquid in the balloon  15 . As a result, even if the liquid is supplied and discharged to and from the liquid feeding path  21  during the cauterization of the diseased part, the surface temperature of the balloon  15  can be uniformly maintained, and the occurrence of uneven cauterization in the diseased part can be prevented. Then, the therapeutic effect can be improved, and the burden on the patient can be reduced. 
     The stirring line connection portion  40  is not provided with the stopcock  35 . In the illustrated example, the stirring line connection portion  40  causes the stirring line  60  and the liquid feeding path  21  to always communicate with each other at least while the stirring line  60  is connected. 
     As illustrated in  FIG.  1   , the heating electrode  70  is fixed to the outer peripheral surface of the inner cylinder shaft  22  inside the balloon  15 . The distal end of the lead wire  71  is connected to the heating electrode  70 . The other end portion of the lead wire  71  is provided with a connector  72  for electrically connecting the lead wire  71  to the heating device  75 . The heating device  75  applies electrical energy to the heating electrode  70  via the lead wire  71  to heat the liquid around the heating electrode  70 . As the heating device  75 , a high frequency generation device capable of generating a high frequency current of 100 Hz or more can be employed, but our catheters are not limited thereto. 
     In the illustrated example, the lead wire  71  is inserted into the liquid feeding path  21 , but our catheters are not limited thereto. 
     As illustrated in  FIG.  1   , the housing  55  includes a narrow portion  57  narrowed in a direction intersecting the first direction D1 in which the proximal end portion of the catheter shaft  20  extends, a first gripping portion  58  connected to the narrow portion  57  from one side (proximal end side) in the first direction D1, and a second gripping portion  59  connected to the narrow portion  57  from the other side (distal end side) in the first direction D1. Since the narrow portion  57  is formed in the housing  55 , both the first gripping portion  58  and the second gripping portion  59  can be easily gripped. In addition, it is possible to prevent the housing  55  from being displaced in the first direction D1 from the hand of a person who grips the housing  55  (person who operates the catheter  10 ) while the housing  55  is gripped. As a result, it is possible to prevent the catheter shaft  20  and the balloon  15  from unintentionally moving along the longitudinal direction of the catheter shaft  20  while the housing  55  is gripped. As a result, it is possible to prevent the catheter shaft  20  and the balloon  15  from being unintentionally separated from the diseased part during cauterization of the diseased part. 
       FIG.  8    illustrates a view of the housing  55  as viewed from its distal end side. In  FIG.  8   , an arrow extending along a direction perpendicular to the paper surface of the drawing is represented by a symbol of a circled dot. 
     In the illustrated example, as illustrated in  FIG.  8   , a maximum radius (“maximum outer radius”) R1 of the circumscribed circle of the first gripping portion  58  about an axis X 1  extending along the first direction D1 is larger than a maximum radius (maximum outer radius) R2 of the circumscribed circle of the second gripping portion  59  about an axis X 2  extending along the first direction D1. The first gripping portion  58  is provided with the operation unit  50  for extending the balloon  15 . As a result, the operation method of the catheter  10  can be visually transmitted. That is, when operating the operation unit  50 , it is necessary to apply a relatively large force capable of releasing the engagement between the movement restricting protrusion  53  and the movement restricting recess  56  to the housing  55  and the operation unit  50 . Therefore, it is understood that the first gripping portion  58  should be firmly gripped to operate operation unit  50  as illustrated in  FIG.  5   . On the other hand, in other instances, since it is sufficient to apply a relatively small force to the housing  55 , it is understood that it is only necessary to lightly hold the second gripping portion  59  as illustrated in  FIG.  7   . 
     Next, an example of a method of operating the catheter system  1  to which the above-described balloon catheter  10  is applied will be described with reference to  FIGS.  1  to  5  and  7   . Hereinafter, an example where the catheter system  1  is applied to ablation treatment of atrial fibrillation will be described. 
     First, the distal end of the catheter  10  is inserted into the pulmonary vein. At this time, the inner cylinder shaft  22  is disposed at the balloon extension position illustrated in  FIG.  4   , and the balloon  15  is extended. No liquid is contained in the balloon  15 . Further, the stopcock  35  is disposed at a closed position (position indicated by a solid line in  FIG.  2   ), and the internal space  31  of the supply-discharge line connection portion  30  is closed. Therefore, communication between the supply-discharge line  36  and the liquid feeding path  21  is blocked. In addition, the stirring line  60  is connected to the stirring line connection portion  40  and the heating device  75  is connected to the connector  72 , but the stirring device  65  and the heating device  75  are not operated. 
     After the distal end of the catheter  10  is inserted into the pulmonary vein, as illustrated in  FIG.  5   , while the second gripping portion  59  of the housing  55  is gripped with one hand H 1 , the first gripping portion  58  of the housing  55  is firmly gripped with the other hand H 2 . Then, while gripping the first gripping portion  58  with the other hand H 2 , the operation unit  50  is moved to the proximal end side of the housing  55  with a finger/fingers of the other hand H 2 . As a result, the inner cylinder shaft  22  moves to the balloon inflatable position illustrated in  FIG.  3   . 
     Next, as illustrated in  FIG.  7   , while the second gripping portion  59  of the housing  55  is gripped with the one hand H 1 , the supply-discharge device  38  is gripped with the other hand H 2 . Then, while gripping the supply-discharge device  38  with the other hand H 2 , the supply-discharge line  36  is curved, and the stopcock  35  is rotated to the open position (position indicated by the broken line in  FIG.  2   ) with the other hand H 2 . As a result, the supply-discharge line  36  and the liquid feeding path  21  communicate with each other. Thereafter, the supply-discharge device  38  is operated with the other hand H 2  to supply the liquid into the liquid feeding path  21  and the balloon  15 . 
     When the balloon  15  is sufficiently inflated by the supplied liquid, as illustrated in  FIG.  7   , the supply-discharge line  36  is curved while the supply-discharge device  38  is gripped by the other hand H 2 , and the stopcock  35  is rotated to the closed position by the other hand H 2 . As a result, the internal space  31  of the supply-discharge line connection portion  30  is closed, and communication between the supply-discharge line  36  and the liquid feeding path  21  is blocked. Thereafter, the stirring device  65  and the heating device  75  are operated to stir the liquid in the balloon  15  while heating the liquid. As a result, the diseased part is cauterized. During the cauterization, the catheter shaft  20  and/or the second gripping portion  59  of the housing  55  are held with one hand H 2  and/or both hands H 1  and H 2  so that the balloon  15  is not separated from the diseased part, and the catheter shaft  20  is retained against the diseased part. 
     When it is determined that the balloon  15  has insufficient liquid or the balloon  15  has excessive liquid during cauterization, the liquid is supplied or discharged while the stirring of the liquid in the balloon  15  by the stirring device  65  is continued. Specifically, as illustrated in  FIG.  7   , the supply-discharge device  38  is gripped with the other hand H 2 , the supply-discharge line  36  is curved while the supply-discharge device  38  is gripped, and the stopcock  35  is rotated to the open position with the other hand H 2 . As a result, the liquid feeding path  21  and the supply-discharge line  36  communicate with each other. Then, the supply-discharge device  38  is operated with the other hand H 2  to supply and discharge the liquid to and from the liquid feeding path  21  and the balloon  15 . During this time, since the liquid in the balloon  15  continues to be stirred by the stirring device  65 , the temperature of the surface of the balloon  15  is maintained uniform. Then, when the amount of the liquid in the balloon  15  reaches an appropriate amount, as illustrated in  FIG.  7   , the supply-discharge line  36  is curved while the supply-discharge device  38  is gripped with the other hand H 2 , and the stopcock  35  is rotated to the closed position with the other hand H 2 . As a result, communication between the liquid feeding path  21  and the supply-discharge line  36  is blocked. 
     When the cauterization is completed, the stirring device  65  and the heating device  75  are stopped. Then, the liquid is discharged from the balloon  15  and the liquid feeding path  21 . Specifically, as illustrated in  FIG.  7   , while the second gripping portion  59  of the housing  55  is gripped with the one hand H 1 , the supply-discharge device  38  is gripped with the other hand H 2 , the supply-discharge line  36  is curved while the supply-discharge device  38  is gripped, and the stopcock  35  is rotated to the open position with the other hand H 2 . As a result, the liquid feeding path  21  and the supply-discharge line  36  communicate with each other. Then, the supply-discharge device  38  is operated with the other hand H 2  to discharge the liquid from the balloon  15  and the liquid feeding path  21 . When the liquid in the balloon  15  is sufficiently discharged, the supply-discharge line  36  is curved while holding the supply-discharge device  38  with the other hand H 2 , and the stopcock  35  is rotated to the closed position with the other hand H 2 . As a result, communication between the liquid feeding path  21  and the supply-discharge line  36  is blocked. 
     Next, the balloon  15  is extended while gripping the second gripping portion  59  of the housing  55  with the one hand H 1 . Specifically, as illustrated in  FIG.  5   , the other hand H 2  firmly grips the first gripping portion  58  of the housing  55 , and a finger/ fingers of the other hand H 2  move the operation unit  50  to the distal end side of the housing  55 . As a result, the inner cylinder shaft  22  moves to the balloon extension position illustrated in  FIG.  4   . Once the balloon  15  is sufficiently extended, the catheter  10  is withdrawn from the pulmonary vein. 
     As described above, the balloon catheter  10  may comprise the housing  55 , the catheter shaft  20  having the proximal end portion disposed in the housing  55  and forming the liquid feeding path  21  communicating with the inside of the balloon  15  attached to the distal end portion of the catheter shaft, the supply-discharge line connection portion  30  which has the internal space  31  communicating with the liquid feeding path  21 , and to which the supply-discharge line  36  that supplies and discharges the liquid to and from the liquid feeding path  21  through the internal space  31  can be connected, and the stopcock  35  capable of closing the internal space  31  of the supply-discharge line connection portion  30 . The position of the supply-discharge line connection portion  30  with respect to the housing  55  is fixed. According to such a balloon catheter  10 , the operability of the stopcock  35  is improved. 
     Further, the balloon catheter  10  may further comprise the supply-discharge line  36  connected to the supply-discharge line connection portion  30  and the supply-discharge device  38  that is connected to the supply-discharge line  36  to supply and discharge the liquid to and from the supply-discharge line  36 . The supply-discharge line  36  includes a soft tube having a length of  200  mm or more. According to such a balloon catheter  10 , the stopcock  35  can be operated while gripping the supply-discharge device  38  in a state where the supply-discharge device  38  is connected to the catheter shaft  20  via the supply-discharge line  36  and the supply-discharge line connection portion  30 . 
     The balloon catheter  10  may further comprise the stirring line connection portion  40  which has the internal space  41  communicating with the liquid feeding path  21 , and to which the stirring line  60  that sucks and discharges the liquid from and into the liquid feeding path  21  through the internal space  41  to stir the liquid in the balloon  15  can be connected. The connection portion between the internal space  41  of the stirring line connection portion  40  and the liquid feeding path  21  is located closer to the distal end portion of the catheter shaft than the connection portion between the internal space  31  of the supply-discharge line connection portion  30  and the liquid feeding path  21 . According to such a balloon catheter  10 , even during supply of the liquid from the supply-discharge line  36  to the liquid feeding path  21  and discharge of the liquid from the liquid feeding path  21  to the supply-discharge line  36 , the liquid can be sucked and discharged from and into the liquid feeding path  21  through the internal space  41  of the stirring line connection portion  40  to stir the liquid in the balloon  15 . As a result, even if the liquid is supplied and discharged to and from the liquid feeding path  21  during the cauterization of the diseased part, the surface temperature of the balloon  15  can be uniformly maintained, and the occurrence of uneven cauterization in the diseased part can be prevented. Then, the therapeutic effect can be improved, and the burden on the patient can be reduced. 
     In addition, in the balloon catheter  10 , the stirring line connection portion  40  may be fixed to the housing  55 . Accordingly, by holding the housing  55 , the stirring line connection portion  40  and the stirring line  60  can be held together with the catheter shaft  20 . 
     In addition, in the balloon catheter  10 , the catheter shaft  20  may include the inner cylinder shaft  22  to which the distal end of the balloon  15  is fixed, and the outer cylinder shaft  24  to which the proximal end of the balloon  15  is fixed, the outer cylinder shaft  24  having a lumen into which the inner cylinder shaft  22  is inserted to form the liquid feeding path  21  between the outer cylinder shaft  24  and the inner cylinder shaft  22 . The housing  55  is provided with the operation unit  50  that moves the inner cylinder shaft  22  relative to the outer cylinder shaft  24  along the first direction D1 in which the proximal end portion of the catheter shaft  20  extends to extend the balloon  15 . According to such a balloon catheter  10 , the operation unit  50  can be operated with the same hand H 2  as the hand H 2  gripping the housing  55 . 
     In addition, in the balloon catheter  10 , the housing  55  may include the narrow portion  57  narrowed in the direction intersecting the first direction D1 in which the proximal end portion of the catheter shaft  20  extends, the first gripping portion  58  connected to the narrow portion  57  from one side in the first direction D1, and the second gripping portion  59  connected to the narrow portion  57  from the other side in the first direction D1. According to such a balloon catheter  10 , it is possible to prevent the housing  55  from being displaced in the first direction D1 from the hand of a person who grips the housing  55  (person who operates the catheter  10 ) while the housing  55  is gripped. As a result, it is possible to prevent the catheter shaft  20  and the balloon  15  from unintentionally moving along the longitudinal direction of the catheter shaft  20  while the housing  55  is gripped. As a result, it is possible to prevent the catheter shaft  20  and the balloon  15  from being unintentionally separated from the diseased part during cauterization of the diseased part. 
     In addition, in the balloon catheter  10 , the catheter shaft  20  may include the inner cylinder shaft  22  to which the distal end of the balloon  15  is fixed, and the outer cylinder shaft  24  to which the proximal end of the balloon  15  is fixed, the outer cylinder shaft  24  having a lumen into which the inner cylinder shaft  22  is inserted to form the liquid feeding path  21  between the outer cylinder shaft  24  and the inner cylinder shaft  22 . The maximum outer radius R1 of the first gripping portion  58  about the axis X 1  extending along the first direction D1 is larger than the maximum outer radius R2 of the second gripping portion  59  about the axis X 2  extending along the first direction D1, and the first gripping portion  58  is provided with the operation unit  50  that moves the inner cylinder shaft  22  relative to the outer cylinder shaft  24  along the first direction D1 to stretch the balloon  15 . According to such a balloon catheter  10 , the operation method of the catheter  10  can be visually transmitted. That is, it is understood that when operating the operation unit  50 , the first gripping portion  58  should be firmly gripped to operate the operation unit  50  as illustrated in  FIG.  5   . On the other hand, in other instances, it is understood that the second gripping portion  59  may be lightly held as illustrated in  FIG.  7   . 
     Alternatively, the balloon catheter  10  may comprise the housing  55  and the catheter shaft  20  having the proximal end portion disposed in the housing  55  and forming the liquid feeding path  21  communicating with the inside of the balloon  15  attached to the distal end portion of the catheter shaft  20 . The housing  55  includes the narrow portion  57  narrowed in the direction intersecting the first direction D1 in which the proximal end portion of the catheter shaft  20  extends, the first gripping portion  58  connected to the narrow portion  57  from one side in the first direction D1, and the second gripping portion  59  connected to the narrow portion  57  from the other side in the first direction D1. According to such a balloon catheter  10 , it is possible to prevent the housing  55  from being displaced in the first direction D1 from the hand of a person who grips the housing  55  (person who operates the catheter  10 ) while the housing  55  is gripped. As a result, it is possible to prevent the catheter shaft  20  and the balloon  15  from unintentionally moving along the longitudinal direction of the catheter shaft  20  while the housing  55  is gripped. As a result, it is possible to prevent the catheter shaft  20  and the balloon  15  from being unintentionally separated from the diseased part during cauterization of the diseased part. 
     Alternatively, the balloon catheter  10  may comprise the housing  55 , the catheter shaft  20  having the proximal end portion disposed in the housing  55  and forming the liquid feeding path  21  communicating with the inside of the balloon  15  attached to the distal end portion of the catheter shaft  20 , the supply-discharge line connection portion  30  which has the internal space  31  communicating with the liquid feeding path  21 , and to which the supply-discharge line  36  that supplies and discharges the liquid to and from the liquid feeding path  21  through the internal space  31  can be connected, and the stirring line connection portion  40  which has the internal space  41  communicating with the liquid feeding path  21 , and to which the stirring line  60  that sucks and discharges the liquid from and into the liquid feeding path  21  through the internal space  41  to stir the liquid in the balloon  15  can be connected. The connection portion between the internal space  41  of the stirring line connection portion  40  and the liquid feeding path  21  is located closer to the distal end portion of the catheter shaft  20  than the connection portion between the internal space  31  of the supply-discharge line connection portion  30  and the liquid feeding path  21 . According to such a balloon catheter  10 , even during supply of the liquid from the supply-discharge line  36  to the liquid feeding path  21  and discharge of the liquid from the liquid feeding path  21  to the supply-discharge line  36 , the liquid can be sucked and discharged from and into the liquid feeding path  21  through the internal space  41  of the stirring line connection portion  40  to stir the liquid in the balloon  15 . As a result, even if the liquid is supplied and discharged to and from the liquid feeding path  21  during the cauterization of the diseased part, the surface temperature of the balloon  15  can be uniformly maintained, and the occurrence of uneven cauterization in the diseased part can be prevented. Then, the therapeutic effect can be improved, and the burden on the patient can be reduced. 
     The above-described example and modifications thereof are included in the scope of this disclosure, and are included in the scope of the appended claims and the equivalents thereof. In addition, as a matter of course, it is also possible to partially appropriately combine the above-described example and modifications thereof within the scope of this disclosure.