Patent Publication Number: US-2021170147-A1

Title: Balloon catheter and method for producing same

Description:
TECHNICAL FIELD 
     One or more embodiments of the present disclosure relate to a balloon catheter in which a balloon has a projecting portion. 
     BACKGROUND 
     It has been known that various diseases are caused by stagnant circulation of blood due to constriction of a blood vessel which is a flow path through which blood is circulated in the body. Particularly when a coronary artery supplying blood to the heart becomes stenosed, serious diseases such as angina or myocardial infarction may be caused. As one of methods for treating such a stenosed part of a blood vessel, technique (for example, angioplasty such as PTA or PTCA) has been used for dilating the stenosed part using a balloon catheter. Angioplasty is a minimally invasive therapy that does not require thoracotomy, such as bypass surgery, and thus is widely used. 
     A stenosed part sclerosed by calcification or the like may occur on the inner wall of a blood vessel. In such a calcified lesion, it is difficult to dilate the sclerosed stenosed part with a common balloon catheter. 
     A method has been used of dilating a stenosed part of a blood vessel by placing an indwelling dilator called a stent in the stenosed part. However, ISR (In-Stent-Restenosis) lesions may occur in which stenosis occurs again in the blood vessel due to excessive neointimal proliferation in the blood vessel after the treatment. In the ISR lesion, the neointima is soft and has a smooth surface. Therefore, when a common balloon catheter is used, the position of the balloon may be displaced from the lesion during inflation of the balloon, so that the blood vessel may be damaged. 
     As balloon catheters that can dilate stenosed parts caused by the calcified lesion or the ISR lesion as described above, there are balloon catheters provided with protrusions on the outer peripheral surface of the balloon (for example, Patent Documents 1 to 4). 
     PATENT DOCUMENTS 
     Patent Document 1: JP-A-2011-513031 
     Patent Document 2: JP-A-2005-517474 
     Patent Document 3: JP-A-2016-521169 
     Patent Document 4: JP-A-2007-135880 
     However, the balloon catheters having protrusions as disclosed in Patent Documents 1 to 4 have poor passage within a blood vessel, because the protrusions protrude radially outward from the central axis of the catheter. Further, depending on the state of the calcified lesion or the ISR lesion, even the balloon catheters as disclosed in Patent Documents 1 to 4 cannot sufficiently dilate the stenosed part. 
     SUMMARY 
     One or more embodiments of the present disclosure has been made in view of the above-described circumstances, and the object thereof is to provide a balloon catheter that has excellent passage within a blood vessel and can sufficiently dilate the stenosed part by applying strong stress on the stenosed part. 
     A balloon catheter of one or more embodiments of the present invention comprises: a shaft having a distal side and a proximal side; and a balloon provided at the distal side of the shaft, wherein the balloon has a plurality of wings in a deflated state, each wing has a projecting portion on an outer surface in a wrapping state, a projecting direction of which is opposite to the wrapping direction of the wing, in cross section perpendicular to a long axis direction of the balloon, a base of the projecting portion has a base first end part farther from a tip of the wing and a base second end part closer to the tip of the wing, and a tip of the projecting portion is closer to a base of the wing respect to a line passing through the base first end part which is perpendicular to a line passing through the base first end part and the base second end part. 
     In one or more embodiments, the balloon catheter is provided wherein, in a cross section perpendicular to a long axis direction of the balloon, a linear component passing through the base first end part and the base second end part in a vector from the base first end part of the projecting portion toward the tip of the wing having the projecting portion, and a linear component passing through the base first end part and the base second end part in a vector from the base first end part of the projecting portion toward the tip of the projecting portion are opposite. 
     In one or more embodiments, the balloon catheter is provided wherein the projecting portion is exposed when the wings are wrapping. 
     In one or more embodiments, the balloon catheter is provided wherein a number of the wings is at least two, and a number of the projecting portion is two or more and five or less. 
     In one or more embodiments, the balloon catheter is provided wherein a number of the projecting portion provided on each of the plurality of wings is at least one. 
     In one or more embodiments, the balloon catheter is provided wherein the projecting portion is at least partially provided with a discontinuous part in a distal and proximal direction of the shaft. 
     In one or more embodiments, the balloon catheter is provided wherein the projecting portion is formed with a plurality of holes aligned in a distal and proximal direction of the shaft. 
     In one or more embodiments, the balloon catheter is provided wherein the projecting portion is formed with a recess extending along a distal and proximal direction of the shaft. 
     In one or more embodiments, the balloon catheter is provided wherein, in a cross section perpendicular to the long axis direction of the balloon, a height from straight line passing through the base first end part and the base second end part to a tip of the projecting portion is greater than a distance from the base first end part to the base second end. 
     In one or more embodiments, the balloon catheter is provided wherein, in a cross section perpendicular to the long axis direction of the balloon, a height from a straight line passing through the base first end part and the base second end part to a tip part of the projecting portion is less than a distance from the base first end part to the base second end part. 
     In one or more embodiments, the balloon catheter is provided wherein, in a cross section perpendicular to the long axis direction of the balloon, the projecting portion has an arc at least at a part from the base first end part to the tip of the projecting portion and at least at a part from the base second end part to the tip of the projecting portion. 
     In one or more embodiments, the balloon catheter provided wherein, in a cross section perpendicular to the long axis direction of the balloon, a distance from a point of intersection where a perpendicular line from the tip of the projecting portion to a straight line passing through the base first end part and the base second end part contacts a straight line passing through the base first end part and the base second end part to the base first end part is greater than a distance from the base first end part to the base second end part. 
     In one or more embodiments, the balloon catheter is provided wherein a material constituting the projecting portion is same as a material constituting the wings. 
     A method for manufacturing a balloon catheter of one or more embodiments of the present disclosure comprises preparing a resin block having a plurality of protrusions in a cross section perpendicular to a long axis direction, protruding directions of the plurality of protrusions having a one-circumferential-direction component; preparing a hollow mold; and placing the resin block inside the mold. 
     In one or more embodiments, the method for manufacturing a balloon catheter is provided wherein the mold has a recessed part in which the protrusions are placeable. 
     The balloon catheter according to one or more embodiments of the present disclosure has a projecting portion on an outer surface of each wing of a balloon in a wrapping state of the wing, wherein a projecting direction of which is opposite to the wrapping direction of the wing. Thus, the balloon catheter has excellent passage within a blood vessel. Further, the balloon easily catches on the stenosed part, and a strong stress can be applied to the stenosed part, whereby the stenosed part can be sufficiently dilated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a balloon catheter according to one or more embodiments of the present disclosure. 
         FIG. 2  is a sectional view of one or more embodiments of the balloon catheter shown in  FIG. 1  along a line II-II. 
         FIG. 3  is an enlarged view of a balloon included in a balloon catheter according to one or more embodiments of the present disclosure. 
         FIG. 4  shows a deflated state of the balloon shown in  FIG. 3  along a line IV-IV. 
         FIG. 5  shows a wrapping state of the balloon shown in  FIG. 4 . 
         FIG. 6  is an enlarged view of a projecting portion of a balloon according to one or more embodiments of the present disclosure. 
         FIG. 7  is a side view showing another example of a balloon according to one or more embodiments of the present disclosure. 
         FIG. 8  is a sectional view showing another example of a balloon according to one or more embodiments of the present disclosure. 
         FIG. 9  is a perspective view of a resin block according to the one or more embodiments of the present disclosure. 
         FIG. 10  is a sectional view of a cavity shape of a mold according to one or more embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     One or more embodiments of the present disclosure will be described below in more detail by way of the following embodiments. However, one or more embodiments of the present disclosure is not limited to the following embodiments. It is obvious that the present invention can be carried out by making modifications, as appropriate, in accordance with the gist described above or later, and such modifications are also included in the technical scope of the present disclosure. Note that, in each drawing, hatching, reference signs for components, and the like may be omitted for convenience of description, and in such a case, the specification and other drawings are to be referred to. Further, the dimensions of the various components in the drawings are not limited to provide for the purpose of facilitating the understanding of the feature of one or more embodiments of the present disclosure, and the dimensions may differ from the actual dimensions in some cases. 
     An overall configuration of a balloon catheter according to one or more embodiments of the present disclosure will be described with reference to  FIGS. 1 to 3 .  FIG. 1  shows a configuration example of a so-called over-the-wire balloon catheter in which a wire is inserted from a distal side to a proximal side of a shaft. One or more embodiments of the present disclosure is also applicable to a so-called rapid exchange balloon catheter in which a wire is inserted from the distal side to a position at the middle between the distal side and the proximal side of the shaft. 
     The balloon catheter  1  has a shaft  2  having a distal side and a proximal side, and a balloon  10  provided on the distal side of the shaft  2 . A hub  5  is provided on the proximal side of the shaft  2 . 
     In one or more embodiments of the present disclosure, the proximal side refers to a user side with respect to the extending direction of the shaft  2 , and the distal side refers to a side opposite to the proximal side, that is, a treatment target side. Further, the extending direction of the shaft  2  is referred to as a long axis direction. The radial direction refers to the radial direction of the shaft  2 , the inner side in the radial direction refers to the direction toward the center of the axis of the shaft  2 , and the outer side in the radial direction refers to the direction toward the opposite side to the inner side. 
     The balloon catheter  1  is configured such that fluid is supplied from the hub  5  to the inside of the balloon  10  through the shaft  2 , and can control inflation and deflation of the balloon  10  using an indeflator (balloon pressurizer). The fluid may be a pressure fluid pressurized by a pump or the like. 
     Commonly, the shaft  2  is internally provided with a fluid flow path and a guide wire insertion path for a guide wire that guides the movement of the shaft  2 . For example, the shaft  2  has an inner tube  3  and an outer tube  4 , wherein the inner tube  3  functions as the insertion path for the guide wire, and a space between the inner tube  3  and the outer tube  4  functions as the fluid flow path. In this case, on the distal side of the shaft  2 , the inner tube  3  extends from the distal end of the outer tube  4  and penetrates the balloon  10  in the axial direction. Thus, the distal side of the balloon  10  is connected to the inner tube  3  and the proximal side of the balloon  10  is connected to the outer tube  4 . 
     The hub  5  includes a fluid injection portion  6  that communicates with the flow path of the pressure fluid, and a guide wire insertion portion  7  that communicates with the insertion path for the guide wire. The guide wire insertion portion  7  having a function of inserting the guide wire there through can also function as an injection port for drug or the like and as a suction port for fluid or the like in a body cavity. 
     The balloon  10 , the shaft  2  (inner tube  3  and outer tube  4 ), and the hub  5  can be joined by using conventionally known joining methods such as a method using an adhesive or heat welding. A radiopaque marker may be placed in the portion of the shaft  2  where the balloon  10  is located in order that an operator can confirm the position of the balloon  10  under X-ray fluoroscopy. 
     In one or more embodiments, the balloon  10  may have a straight tube portion  11  as shown in  FIG. 3 . When the balloon  10  is configured as described above, the contact area between the balloon  10  and the stenosed part can be increased, whereby the stenosed part can be easily dilated. In one or more embodiments, the balloon  10  may have a proximal tapered portion  12  connected to the proximal side of the straight tube portion  11 , and a distal tapered portion  13  connected to the distal side of the straight tube portion  11 , the proximal tapered portion  12  and the distal tapered portion  13  being reduced in diameter with distance from the straight tube portion  11 . Due to such configuration of the balloon  10 , the strength of the balloon  10  can be increased. In addition, a step generated when the balloon  10  is wrapped around the shaft  2  can be reduced, whereby the balloon  10  can be easily inserted into a blood vessel. In order to fix the balloon  10 , a cylindrical proximal sleeve  14  may be connected to the proximal side of the proximal tapered portion  12 , and a cylindrical distal sleeve  15  may be connected to the distal side of the distal tapered portion  13 . In the balloon catheter  1  shown in  FIG. 1 , the proximal sleeve  14  is joined to the outer tube  4  of the shaft  2 , and the distal sleeve  15  is joined to the inner tube  3  of the shaft  2 . The balloon  10  can be configured such that the distal tapered portion  13  is inflated by a fluid supplied from the proximal tapered portion  12  through the straight tube portion  11 . In one or more embodiments of the present disclosure, an inflatable part is regarded as the balloon  10 . 
     Examples of the material constituting the balloon  10  include: polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; polyester resins such as polyethylene terephthalate and polyester elastomers; polyurethane resins such as polyurethane and polyurethane elastomers; polyphenylene sulfide resins; polyamide resins such as polyamide or polyamide elastomers; fluorine resins; silicon resins; and natural rubber such as latex rubber. These materials may be used alone, or two or more of them may be used in combination. Among them, polyamide resin, polyester resin, and polyurethane resin may be used. Particularly, an elastomer resin may be used from the viewpoint of reduction in thickness and flexibility of the balloon. Among polyamide resins, nylon 11 and nylon 12, for example, can be used as materials suitable for the balloon 10, and nylon 12 is suitably used because it can be relatively easily molded during blow molding. From the viewpoint of reduction in thickness and flexibility of the balloon  10 , a polyamide elastomer, such as a polyether ester amide elastomer or a polyamide ether elastomer, may be used. Among them, a polyether ester amide elastomer may be used from the viewpoint of high yield strength and high dimensional stability of the balloon  10 . 
     In one or more embodiments, the outer diameter of the balloon  10  may be 0.5 mm or more, 1 mm or more, or 3 mm or more. Due to the lower limit value of the outer diameter of the balloon  10  being set as described above, the stenosed part in the blood vessel can be sufficiently dilated. Further, in one or more embodiments the outer diameter of the balloon  10  may be 35 mm or less, 30 mm or less, or 25 mm or less. Due to the upper limit value of the outer diameter of the balloon  10  being set as described above, a sufficient blood flow path can be ensured in a blood vessel. 
     In one or more embodiments, the length of the balloon  10  in the long axis direction may be 5 mm or more, 10 mm or more, or 15 mm or more. Due to the lower limit value of the length of the balloon  10  in the long axis direction being set as described above, the area of the stenosed part that can be dilated at a time can be increased. In addition, in one or more embodiments the length of the balloon  10  in the long axis direction may be 300 mm or less, 200 mm or less, or 100 mm or less. Due to the upper limit value of the length of the balloon  10  in the long axis direction being set as described above, a load during inflation of the balloon  10  can be reduced. 
     In one or more embodiments, the thickness of the balloon  10  may be 5 μm or more, 7 μm or more, or 10 μm or more. Due to the lower limit value of the thickness of the balloon  10  being set as described above, sufficient strength of the balloon  10  can be obtained. In one or more embodiments, the thickness of the balloon  10  may be 45 μm or less. The thickness of the balloon  10  can be set according to the purpose of use of the balloon catheter. For example, when used as a high pressure resistant balloon, the balloon  10  may have a thickness of 30 μm or more and 45 μm or less in one or more embodiments. Moreover, when it is desired to improve the passage of the balloon portion, the thickness may be set to 30 μm or less in one or more embodiments. 
     As shown in  FIG. 4 , the balloon  10  of one or more embodiments has a plurality of wings  21  in a deflated state. The wing  21  refer to portions where the inner surfaces of the balloon  10  are partly in contact with each other when the balloon  10  is deflated. 
     In one or more embodiments, the number of the wing  21  may be one or more, and may be at least two or three. Due to such configuration of the wings  21 , the balloon  10  is easily folded when being deflated. Each wing  21  may have a discontinuous part  23 , which will be described later, in distal and proximal direction of the shaft  2 . Even if the wing  21  has the discontinuous part  23  in the distal and proximal direction of the shaft  2 , such wing  21  is regarded as a single piece. 
     As shown in  FIG. 5 , each wing  21  has a projecting portion  22  on an outer surface in a wrapping state. The wrapping state of the wing  21  refers to a state in which the wing  21  is folded while being wrapped along the outer periphery of the balloon  10  in the deflated state of the balloon  10 . 
     The projecting direction of the projecting portion  22  has a component in the direction opposite to the wrapping direction of the wing  21 . In other words, the projecting direction of the projecting portion  22  of which is opposite to the wrapping direction of the wing  21 . That is, as shown in  FIG. 6 , the projecting portion  22  is configured such that an angle between a straight line connecting a base  22   a  of the projecting portion  22  and a tip  22   b  of the projecting portion  22  and a straight line connecting the base  22   a  of the projecting portion  22  and a tip  21   b  of the wing  21  exceeds 90 degrees. Due to such configuration of the projecting portion  22 , when the balloon  10  passes through a blood vessel, the projecting portion  22  is less likely to catch on the inner wall of the blood vessel, whereby passage of the balloon  10  within the blood vessel can be improved. Further, when the balloon  10  is inserted while being rotated in the direction from the tip  22   b  of the projecting portion  22  toward the tip  21   b  of the wing  21  during passage of the balloon  10  through the blood vessel, interference between the projecting portion  22  and the inner wall of the blood vessel can be prevented, whereby the passage of the balloon  10  within the blood vessel can be further improved. 
     In a cross section perpendicular to a long axis direction of the balloon  10 , the base  22   a  of the projecting portion  22  has a base first end part  22   a   1  farther from the tip  21   b  of the wing  21  and a base second end part  22   a   2  closer to the tip  21   b  of the wing  21 , and the tip  22   b  of projecting portion  22  is perpendicular to a straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2 , and is closer to the base of the wing  21  than a straight line passing through the base first end part  22   a   1 . In other words, a tip  22   b  of the projecting portion  22  is closer to a base of the wing  21  respect to a line passing through the base first end part  22   a   1  which is perpendicular to a line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2 . Due to such configuration of the projecting portion  22 , passage of the balloon  10  within the blood vessel can be improved. 
     Examples of the material constituting the projecting portion  22  include: metal such as stainless steel, aluminum, aluminum alloy, titanium, titanium alloy, copper, copper alloy, tantalum, or cobalt alloy; and synthetic resins including polyolefin resins such as polyvinyl chloride, polyethylene, polypropylene, or cyclic polyolefin, polystyrene resins, polymethylpentene resins such as poly-(4-methylpentene-1), polycarbonate resins, acrylic resins, ABS resins, polyester resins such as polyethylene terephthalate, or polyethylene naphthalate, and polyamide resins such as butadiene-styrene copolymer, nylon 6, nylon 6,6, nylon 6,10, or nylon 12. These materials may be used alone, or two or more of them may be used in combination. It is provided that the material constituting the projecting portion  22  of one or more embodiments may be the same as the material constituting the wing  21 . That is, in one or more embodiments it may be provided that the material constituting the projecting portion  22  is the same as the materials constituting the balloon  10  and the wing  21 . Due to such configuration of the projecting portion  22 , the joint strength between the wing  21  and the projecting portion  22  can be increased. Further, the wing  21  and the projecting portion  22  are integrated in one or more embodiments, which will be described later. When the wing  21  and the projecting portion  22  are configured as described above, the joint strength between the wing  21  and the projecting portion  22  can be increased, whereby the strength of the balloon  10  can be increased. 
     In one or more embodiments, the Shore hardness of the projecting portion  22  is 30 D or more and 80 D or less, and the Rockwell hardness of the projecting portion  22  is 50 or more and 150 or less. When being configured as described above, the projecting portion  22  can easily catch on the stenosed part. When a resin having the hardness as described above is selected from the abovementioned materials, the projecting portion  22  can be formed to have a predetermined hardness. 
     As shown in  FIG. 6 , in one or more embodiments it is provided that, in a cross section perpendicular to the long axis direction of the balloon  10 , a direction which is an extending direction of the wing  21  and which is from the base first end part  22   a   1  toward the tip part  21   b  of the wing  21  has a one-circumferential-direction component with respect to the long axis of the balloon  10 , and a direction which is from the base first end part  22   a   1  toward the tip part  22   b  of the projecting portion  22  has an other-circumferential-direction component with respect to the long axis of the balloon  10 . That is, in one or more embodiments it is provided that the direction from the base first end part  22   a   1  toward the tip part  22   b  has a component in the direction from the tip part  21   b  of the wing  21  toward the base first end part  22   a   1 . In other words, a linear component passing through the base first end part  22   a   1  and the base second end part  22   a   2  in a vector from the base first end part  22   a   1  of the projecting portion  22  toward the tip part  21   b  of the wing  21  having the projecting portion  22 , and a linear component passing through the base first end part  22   a   1  and the base second end part  22   a   2  in a vector from the base first end part  22   a   1  of the projecting portion  22  toward the tip part  22   b  of the projecting portion  22  are opposite. Due to such configuration of the projecting portion  22 , the projecting portion  22  is less likely to interfere with the inner wall of the blood vessel when the balloon  10  passes through the blood vessel, whereby the passage of the balloon  10  within the blood vessel can be improved. 
     In one or more embodiments, the projecting portion  22  is exposed when the wing  21  is wrapping. That is, in one or more embodiments it is provided that the projecting portion  22  is at a position where the wings  21  do not overlap each other when the wings  21  are wrapping. Due to such configuration of the projecting portion  22 , when the balloon  10  is inflated at the stenosed part, the projecting portion  22  easily catches on the stenosed part in the middle of the inflation of the balloon  10 . Thus, the balloon  10  is easily fixed to the stenosed part, whereby the stenosed part can be easily dilated. 
     Particularly, in one or more embodiments the projecting portion  22  is provided at a location exposed on the outermost surface in a wrapping state and closer to the tip part  21   b  of the wing  21  in an area from the tip part  21   b  to the root part of the wing  21 . Due to such configuration of the projecting portion  22 , the projecting portion  22  easily catches on the stenosed part in an initial stage of the inflation of the balloon  10 . Further, due to the presence of the projecting portion  22  at the tip part  21   b  of the wing  21 , when the inflated balloon  10  is again deflated, the balloon  10  easily returns to the state, the same as the state before inflation, where the wing  21  is wrapping. Thus, even when the balloon  10  is inserted into the blood vessel again, the balloon  10  can satisfactorily pass through the blood vessel. 
     In one or more embodiments, the number of the projecting portions  22  is two or more, and three or more. Due to the lower limit value of the number of the projecting portions  22  being set as described above, the balloon  10  can be reliably fixed to the stenosed part. Further, in one or more embodiments the number of the projecting portions  22  is five or less, and four or less. Due to the upper limit value of the number of the projecting portions  22  being set as described above, the passage of the balloon  10  within the blood vessel can be enhanced. In one or more embodiments, the number of the projecting portions  22  is the same as the number of the wings  21 . In one or more embodiments, each of the wings  21  are provided with one projecting portion  22 . However, each of the wings  21  may be provided with a plurality of projecting portions  22 . When each of the wings  21  is provided with a plurality of projecting portions  22 , the projecting portions  22  may be provided adjacent to each other or separated from each other. 
     In one or more embodiments, it is provided that at least one projecting portion  22  is on each of the plurality of wings  21 . Due to such configuration of the projecting portion  22 , the balloon  10  can be firmly fixed to the stenosed part, whereby the stenosed part can be efficiently dilated. 
     In one or more embodiments, it is provided that the number of the projecting portions  22  is equal to the number of the wings  21 , and each of the wings  21  is provided with one projecting portion  22 . Particularly, in one or more embodiments it is provided that the number of the wings  21  is two or more and five or less, the number of the projecting portions  22  is equal to the number of the wings  21 , and each of the wings  21  is provided with one projecting portion  22 . Due to such configuration of the projecting portion  22 , it is possible to achieve both improvement in passage of the balloon  10  within the blood vessel and dilation force for the stenosed part. 
     As shown in  FIG. 6 , in one or more embodiments it is provided that, in a cross section perpendicular to the long axis direction of the balloon  10 , a height L 1  from the base  22   a  of the projecting portion  22  to the tip  22   b  of the projecting portion  22  may be greater than a length L 2  of the base  22   a  of the projecting portion  22 . The length L 2  indicates the length of the base  22   a  of the projecting portion  22  in the wrapping direction of the wing  21 . That is, in one or more embodiments in a cross section perpendicular to the long axis direction of the balloon  10 , a height is provided from a straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  to a tip  22   b  of the projecting portion  22  may be greater than a distance from the base first end part  22   a   1  to the base second end part  22   a   2 . Due to such configuration of the projecting portion  22 , the projecting portion  22  easily catches on the stenosed part, whereby the stenosed part is easily dilated. When the length of the base  22   a  is increased, that is, when the base  22   a  is thick, the projecting portion  22  is less likely to collapse, which is effective for dilating the stenosed part. 
     In one or more embodiments, the height of the projecting portion  22  is 0.03 mm or more, 0.05 mm or more, and 0.10 mm or more. Due to the lower limit value of the height of the projecting portion  22  being set as described above, the projecting portion  22  is easily fixed to the stenosed part, whereby the stenosed part is easily dilated. Further, in one or more embodiments the height of the projecting portion  22  is 1.00 mm or less, 0.80 mm or less, and 0.65 mm or less. Due to the upper limit value of the height of the projecting portion  22  being set as described above, the passage of the balloon  10  within the blood vessel can be improved. Note that the height of the projecting portion  22  refers to the height L 1  from the base  22   a  of the projecting portion  22  to the tip  22   b  of the projecting portion  22 . 
     In one or more embodiments, the length of the base  22   a  of the projecting portion  22  is 0.01 mm or more, 0.03 mm or more, and 0.05 mm or more. Due to the lower limit value of the length of the base  22   a  of the projecting portion  22  being set as described above, the projecting portion  22  can be easily hooked and fixed on the stenosed part, whereby the stenosed part is easily dilated. Further, in one or more embodiments the length of the base  22   a  of the projecting portion  22  is 1.20 mm or less, 1.00 mm or less, and 0.85 mm or less. Due to the upper limit value of the length of the base  22   a  of the projecting portion  22  being set as described above, the projecting portion  22  is less likely to interfere with the inner wall of the blood vessel while the balloon  10  passes through the blood vessel. The length of the base part  22   a  of the projecting portion  22  refers to the length L 2  from a base first end part  22   a   1  to a second end  22   a   2  of the base  22   a  of the projecting portion  22 . 
     In one or more embodiments it is also provided that, in a cross section perpendicular to the long axis direction of the balloon  10 , the height L 1  from the base  22   a  of the projecting portion  22  to the tip  22   b  of the projecting portion  22  is less than the length L 2  of the base  22   a  of the projecting portion  22 . That is, in one or more embodiments it is also provided that in cross section perpendicular to the long axis direction of the balloon  10 , a height from a straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  to a tip  22   b  of the projecting portion  22  is less than a distance from the base first end part  22   a   1  to the base second end part  22   a   2 . Such configuration of the projecting portion  22  can provide an effect of making the projecting portion  22  easily catch on the stenosed part in the middle of inflation of the balloon  10  and an effect of improving passage of the balloon  10  within the blood vessel. 
     As shown in  FIGS. 7 and 8 , in one or more embodiments it is provided that the projecting portion  22  is at least partially provided with the discontinuous part  23  in the distal and proximal direction of the shaft  2 . Due to such configuration of the projecting portion  22 , the projecting portion  22  can be made flexible and less likely to interfere with the inner wall of the blood vessel while the balloon  10  passes through the blood vessel. 
     The discontinuous part  23  may have a depth from the tip  22   b  of the projecting portion  22  to the base  22   a  of the projecting portion  22 , or may have a depth from the tip  22   b  of the projecting portion  22  to the middle between the tip  22   b  of the projecting portion  22  and the base  22   a  of the projecting portion  22 . That is, the discontinuous part  23  may exist throughout the height of the projecting portion  22  or may exist up to the middle of the projecting portion  22  in the height direction. In one or more embodiments it is provided that the discontinuous part  23  has a depth from the tip  22   b  of the projecting portion  22  to the base  22   a  of the projecting portion  22 . Due to such configuration of the discontinuous part  23 , the flexibility of the projecting portion  22  can be increased. 
     In one or more embodiments, the number of the discontinuous part  23  may be one, but it is provided to be two or more. Due to such configuration of the discontinuous part  23 , the projecting portion  22  becomes more flexible. 
     In one or more embodiments, the length of the discontinuous part  23  in the distal and proximal direction is 0.03 mm or more, 0.05 mm or more, and 0.10 mm or more. Due to the lower limit value of the length of the discontinuous part  23  in the distal and proximal direction being set as described above, the projecting portion  22  can be made more flexible. Further, in one or more embodiments the length of the discontinuous part  23  in the distal and proximal direction is 1.00 mm or less, 0.80 mm or less, and 0.65 mm or less. Due to the upper limit value of the length of the discontinuous part  23  in the distal and proximal direction being set as described above, flexibility and rigidity of the projecting portion  22  can be balanced, whereby the projecting portion  22  can reliably catch on the stenosed part. 
     In one or more embodiments, the total length of the discontinuous parts  23  in the distal and proximal direction is shorter than the total length of the projecting portion  22  in the distal and proximal direction. Due to such configuration of the projecting portion  22 , the projecting portion  22  becomes flexible, which improves passage of the balloon  10  within the blood vessel. Further, the projecting portion  22  has rigidity enough to catch on the stenosed part, whereby the balloon  10  catches on the stenosed part and can sufficiently dilate the stenosed part. 
     In one or more embodiments, the projecting portion  22  is formed with a plurality of holes  24  aligned in the distal and proximal direction of the shaft  2 . Due to such configuration of the projecting portion  22 , the flexibility of the projecting portion  22  is increased, so that the projecting portion  22  easily bends in the circumferential direction of the balloon  10 . Thus, the projecting portion  22  is less likely to catch on the inner wall of the blood vessel when the balloon  10  passes through the blood vessel. 
     The shape of each hole  24  is not particularly limited, and may be a circle, an ellipse, a polygon, or the like. Among these, a circle or an ellipse is provided in one or more embodiments. Due to such configuration of the holes  24 , when stress is applied to the projecting portion  22 , damage of the projecting portion  22  such as rupture of the projecting portion  22  from the holes  24  can be prevented. 
     In one or more embodiments, the length of each hole  24  in the long axis direction is shorter than the length L 1  from the tip part  22   b  of the projecting portion  22  to the base part  22   a  of the projecting portion  22 . That is, in one or more embodiments the length of the hole  24  in the long axis direction is shorter than the height of the projecting portion  22 . Due to such configuration of the holes  24 , the projecting portion  22  becomes adequately rigid, so that the projecting portion can easily catch on the stenosed part. 
     In addition, it is also provided in one or more embodiments that a recess  25  extending along the distal and proximal direction of the shaft  2  is formed in the projecting portion  22 . The recess  25  is, for example, a groove or a hole-shaped dent that does not penetrate. Due to such configuration of the projecting portion  22 , the projecting portion  22  becomes flexible and is less likely to catch on the inner wall of the blood vessel when the balloon  10  passes through the blood vessel. 
     It is also provided in one or more embodiments that the projecting portion  22  has both a plurality of holes  24  and the recess  25  formed therein. Due to such configuration of the projecting portion  22 , the flexibility of the projecting portion  22  can be further increased, whereby the passage of the balloon  10  within the blood vessel can be further improved. 
     It is provided in one or more embodiments that, in a cross section perpendicular to the long axis direction of the balloon  10 , the projecting portion  22  has an arc  26  that protrudes toward the tip part  21   b  of the wing  21 . In other words, it is provided in one or more embodiments that, in the projecting portion  22 , at least one of the surfaces along the long axis direction of the balloon  10  is a curved surface protruding toward the tip  21   b  of the wing  21 . Due to such configuration of the projecting portion  22 , the projecting portion  22  easily catches on the stenosed part even in the middle of the inflation of the balloon  10 , whereby the stenosed part can be more efficiently dilated. 
     It is provided in one or more embodiments that, in a cross section perpendicular to the long axis direction of the balloon  10 , the projecting portion  22  has the arc  26  on a side opposite to the tip  21   b  of the wing  21 . Due to such configuration of the projecting portion  22 , the projecting portion  22  can easily catch on the stenosed part. 
     In one or more embodiments, it is provided that, in cross section perpendicular to the long axis direction of the balloon  10 , the projecting portion  22  has an arc at least at a part from the base first end part  22   a   1  to the tip  22   b  of the projecting portion  22  and at least at a part from the base second end part  22   a   2  to the tip  22   b  of the projecting portion  22 . Due to such configuration of the projecting portion  22 , increase the rigidity of the projecting portion  22 , the projecting portion  22  can easily catch on the stenosed part. 
     In one or more embodiments, it is provided that, in cross section perpendicular to the long axis direction of the balloon  10 , the projecting portion  22  has a first arc from the base first end part  22   a   1  to the tip  22   b  of the projecting portion  22  and a second arc from the base second end part  22   a   2  to the tip  22   b  of the projecting portion  22 , the first arc and the second arc are convex in the same direction, and the length of the first arc is shorter than the length of the second arc. Due to such configuration of the projecting portion  22 , the projecting portion  22  can easily catch on the stenosed part. 
     It is provided in one or more embodiments that, in a cross section perpendicular to the long axis direction of the balloon  10 , the base  22   a  of the projecting portion  22  includes a base first end part  22   a   1  farther from the tip  21   b  of the wing  21 , and a base second end part  22   a   2  closer to the tip  21   b  of the wing  21 , and with respect to the outer surface of the wing  21 , a distance L 3  from a point P 1  where a perpendicular line X 2  from the tip  22   b  of the projecting portion  22  to a straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  is in contact with the outer surface of the wing  21  to the base first end part  22   a   1  is greater than a distance L 2  from the base first end part  22   a   1  to the base second end part  22   a   2 . That is, it is also provided in one or more embodiments that on the outer surface of the wing  21  in cross section perpendicular to the long axis direction of the balloon  10 , a distance from a point of intersection where a perpendicular line X 2  from the tip  22   b  of the projecting portion  22  to a straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  contacts a straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  to the base first end part  22   a   1  is greater than a distance L 2  from the base first end part  22   a   1  to the base second end part  22   a   2 . Due to such configuration of the projecting portion  22 , the projecting portion  22  is less likely to interfere with the inner wall of the blood vessel while the balloon  10  passes through the blood vessel, whereby passage of the balloon  10  is improved. In addition, the projecting portion  22  easily catches on the stenosed part, whereby the stenosed part can be efficiently dilated. In addition, when the balloon  10  is rotated in the direction from the tip  21   b  of the wing  21  toward the projecting portion  22  while being placed in the stenosed part, the projecting portion  22  more easily catches on the stenosed part, whereby the stenosed part is more easily dilated. 
     In one or more embodiments, the distance L 3  from the point P 1  where the perpendicular line X 2  from the tip  22   b  of the projecting portion  22  to the straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  is in contact with the outer surface of the wing  21  to the base first end part  22   a   1  is 1.1 times or more, 1.2 times or more, and 1.3 times or more the distance L 2  from the base first end part  22   a   1  to the second end part  22   a   2 . Due to the lower limit value of the ratio between the distance L 3  and the distance L 2  being set as described above, the projecting portion  22  is less likely to interfere with the inner wall of the blood vessel while the balloon  10  passes through the blood vessel. Further, in one or more embodiments the distance L 3  from the point P 1  where the perpendicular line X 2  from the tip  22   b  of the projecting portion  22  to the straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  is in contact with the outer surface of the wing  21  to the base first end part  22   a   1  is 2.0 times or less, 1.8 times or less, and 1.5 times or less the distance L 2  from the base first end part  22   a   1  to the base second end part  22   a   2 . Due to the upper limit value of the ratio between the distance L 3  and the distance L 2  being set as described above, the projecting portion  22  can more easily catch on the stenosed part. 
     It is provided in one or more embodiments that, in a cross section perpendicular to the long axis direction of the balloon  10 , the distance L 3  from the point P 1  where the perpendicular line X 2  from the tip  22   b  of the projecting portion  22  to the straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  is in contact with the outer surface of the wing  21  to the base first end part  22   a   1  is less than the height L 1  from the base  22   a  of the projecting portion  22  to the tip  22   b  of the projecting portion  22 . That is, it is provided in one or more embodiments that the distance L 3  from the point P 1  where the perpendicular line X 2  from the tip  22   b  of the projecting portion  22  to the straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  is in contact with the outer surface of the wing  21  to the base first end part  22   a   1  is greater than the distance L 2  from the base first end part  22   a   1  to the base second end part  22   a   2  and less than the height L 1  from the base  22   a  of the projecting portion  22  to the tip  22   b  of the projecting portion  22 . Due to such configuration of the projecting portion  22 , it is possible to improve both passage of the balloon  10  within the blood vessel and efficiency in dilating the stenosed part. 
     In one or more embodiments, the distance L 3  from the point P 1  where the perpendicular line X 2  from the tip  22   b  of the projecting portion  22  to the straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  is in contact with the outer surface of the wing  21  to the base first end part  22   a   1  is 0.03 mm or more, 0.05 mm or more, and 0.10 mm or more. Due to the lower limit value of the distance L 3  being set as described above, the projecting portion  22  more easily catches on the stenosed part. Further, in one or more embodiments the distance L 3  from the point P 1  where the perpendicular line X 2  from the tip  22   b  of the projecting portion  22  to the straight line X 1  passing through the base first end part  22   a   1  and the base second end part  22   a   2  is in contact with the outer surface of the wing  21  to the base first end part  22   a   1  is 1.00 mm or less, 0.85 mm or less, and 0.65 mm or less. Due to the upper limit value of the distance L 3  being set as described above, the projecting portion  22  is less likely to interfere with the inner wall of the blood vessel while the balloon  10  passes through the blood vessel, whereby passage of the balloon  10  can be improved. 
     In one or more embodiments, it is provided that, in a cross section perpendicular to the long axis direction of the balloon  10 , the projecting portion  22  has two arcs  26  protruding toward the tip  21   b  of the wing  21 . One of the two arcs connects the tip  22   b  of the projecting portion  22  and the base part  22   a   1  of the projecting portion  22 , and the other connects the tip  22   b  of the projecting portion  22  and the base part  22   a   2  of the projecting portion  22 . In other words, in one or more embodiments it is provided that, in the projecting portion  22 , the two surfaces along the long axis direction of the balloon  10  are curved surfaces protruding toward the tip  21   b  of the wing  21 . Due to such configuration of the projecting portion  22 , the projecting portion  22  easily catches on the stenosed part. 
     A method for producing the balloon catheter according to one or more embodiments of the present disclosure includes: a step of preparing a resin block having a plurality of protrusions in a cross section perpendicular to the long axis direction, the protruding directions of the plurality of protrusions having a one-circumferential-direction component; a step of preparing a hollow mold; and a step of placing the resin block inside the mold. 
     As shown in  FIG. 9 , the balloon  10  is produced using a resin block  110  having a plurality of protrusions  111  in a cross section perpendicular to the long axis direction, the protruding directions of the plurality of protrusions  111  having a one-circumferential-direction component. The balloon  10  is produced by blow molding. 
     When the balloon  10  is produced, the resin block  110  having a plurality of protrusions  111  is prepared. A cylindrical resin block (parison)  110  is produced by extrusion molding. In a cross section perpendicular to the long axis direction, the protruding directions of the protrusions  111  have a one-circumferential-direction component. That is, in a cross section perpendicular to the long axis direction of the resin block  110 , the protruding directions of the protrusions  111  are inclined in the same direction. Since the resin block  110  is configured as described above, the projecting portion  22  can be formed integrally with the balloon  10 . 
     Before stretch blow molding is performed, a step may be added of stretching and extending the portion in the axial direction to become the proximal tapered portion  12  and the distal tapered portion  13  in the resin block  110  while locally heating the portion to be molded as the proximal tapered portion  12  and the distal tapered portion  13  of the balloon  10  shown in  FIG. 3 . Thus, the molded tapered portions  12  and  13  can be sufficiently reduced in thickness. In that case, the portion which has been reduced in thickness by stretching is cut while leaving a predetermined length, whereby a preformed resin block  110  is formed. 
     Meanwhile, a hollow mold is prepared. The mold may be hollow so that the resin block  110  can be placed therein. As shown in  FIG. 10 , the mold  120  has recessed parts  121  in which the protrusions  111  can be placed in one or more embodiments. Since the mold  120  has such a cavity, the tip part  22   b  of the projecting portion  22  can be sharpened, whereby the balloon  10  can easily catch on the stenosed part. The cavity of the mold  120  indicates the shape inside the mold  120 . 
     A single mold  120  may be used, or a plurality of molds  120  may be used. It is provided in one or more embodiments to form the balloon  10  using a plurality of molds  120  by changing the shapes of the cavity of the mold  120  and the recessed parts  121  in a stepwise manner from the shape of the resin block  110  to the shape of the balloon  10 . Due to such molding of the balloon  10 , the mass production of the balloons  10  having small errors in shape and dimension is enabled. 
     Then, the resin block  110  is placed inside the mold  120 . The resin block  110  is placed in the cavity of the mold  120 . When the mold  120  has the recessed parts  121 , the protrusions  111  are placed in the recessed parts  121 . Then, the mold  120  is closed, and compressed air is supplied to the interior, by which the resin block  110  is expanded and molded into the cavity shape. The blow molding may be performed under heating conditions, and may be performed several times. Further, stretching in the radial direction and stretching in the long axis direction may be simultaneously performed, or after either of the stretching in the radial direction or the stretching in the long axis direction is performed, the other may be performed. Stretching and blowing may be performed at the same time, or after either of stretching or blowing is performed, the other may be performed. After blow molding, the compressed air is removed from the inside of the balloon  10 . At this time, in one or more embodiments the balloon  10  is heat fixed in order to fix the folds and dimensions of the balloon  10  to improve foldability during rewrapping and to increase strength. Specifically, it is provided in one or more embodiments that the compressed air is removed from the inside of the balloon  10  with portions where the folds are to be formed being pressed or with a mold having a predetermined shape being in contact with the balloon. 
     In order to form the holes  24  or the recess  25  in the projecting portion  22  of the balloon  10 , the recessed part  121  inside the mold  120  is configured to have a member that can form the recess  25 , or the holes  24  and the recess  25  are formed in the projecting portion  22  of the balloon  10  after blow molding by post treatment, for example. After the balloon  10  is molded, the holes  24  can be formed in the projecting portion  22  by laser processing or punching. In particular, it is provided in one or more embodiments to form the holes  24  and the recess  25  in the projecting portion  22  by using a configuration in which the recessed part  121  includes a member that can form the holes  24  and the recess  25 . By adopting such a method, it is possible to produce the balloon  10  with a small error in position, shape, and dimensions of the holes  24  and the recess  25  in a short time. 
     As described above, the balloon catheter according to one or more embodiments of the present disclosure includes: a shaft having a distal side and a proximal side; and a balloon provided at the distal side of the shaft, wherein the balloon has a plurality of wings in a deflated state, the each wing has a projecting portion on an outer surface in a wrapping state, and a projecting direction of which is opposite to the wrapping direction of the wing, in cross section perpendicular to a long axis direction of the balloon, a base of the projecting portion has a base first end part farther from a tip of the wing and a base second end part closer to the tip of the wing, and a tip of the projecting portion is closer to a base of the wing respect to a line passing through the base first end part which is perpendicular to a line passing through the base first end part and the base second end part. With such a configuration, passage of the balloon within a blood vessel can be improved. Further, the balloon can easily catch on the stenosed part, and a strong stress is applied to the stenosed part, whereby the stenosed part can be sufficiently dilated. 
     The present application claims the benefit of priority based on Japanese patent application number 2017-230943 filed on Nov. 30, 2017. The entire content of the specification of Japanese patent application number 2017-230943 filed on Nov. 30, 2017 is incorporated herein by reference. 
     DESCRIPTION OF REFERENCE SIGNS 
       1 : balloon catheter 
       2 : shaft 
       3 : inner tube 
       4 : outer tube 
       5 : hub 
       6 : fluid injection portion 
       7 : guide wire insertion portion 
       10 : balloon 
       11 : straight tube portion 
       12 : proximal tapered portion 
       13 : distal tapered portion 
       14 : proximal sleeve 
       15 : distal sleeve 
       21 : wing 
       21   b : tip part of wing 
       22 : projecting portion (projection) 
       22   a : base of projecting portion 
       22   a   1 : base first end part 
       22   a   2 : base second end part 
       22   b : tip of projecting portion 
       23 : discontinuous part 
       24 : hole 
       25 : recess 
       26 : arc 
       110 : resin block 
       111 : protrusion 
       120 : mold 
       121 : recessed part 
     X 1 : straight line passing through base first end part and base second end part 
     X 2 : perpendicular line from tip of projecting portion to straight line X 1   
     P 1 : point where perpendicular line X 2  and outer surface of wing contact 
     L 1 : height from base of projecting portion to tip of projecting portion 
     L 2 : length of base of projecting portion (distance from base first end part to base second end part) 
     L 3 : distance from point P 1  to base first end part 
     Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.