Patent Description:
A balloon catheter is widely known as a medical device that dilates a lesion area such as a stenosed site formed in a body lumen such as a blood vessel. Generally, there are an over-the-wire type balloon catheter and a rapid exchange type balloon catheter.

As described in PTL <NUM>, in the rapid exchange type balloon catheter, a guide wire lumen into which a guide wire is inserted is formed only on a distal side of a catheter shaft in which a balloon is disposed. For this reason, a guide wire port (proximal opening portion) through which the guide wire can be inserted into and removed from the guide wire lumen is provided at a predetermined position on the distal side of the catheter shaft in an axial direction (longitudinal direction).

In a catheter shaft used in the rapid exchange type balloon catheter, an outer distal shaft, an outer proximal shaft, and an inner shaft which are configuration elements of the catheter shaft are integrated with each other by heat-welding, and a guide wire port is formed in the vicinity of a proximal portion of the inner shaft. Note that each of the outer distal shaft and the outer proximal shaft is a tubular member forming an inflation lumen through which a pressurizing medium (working fluid) for inflating a balloon flows. The inner shaft is a tubular member including a lumen forming a guide wire lumen.

PTL <NUM>: <CIT>. <CIT> discloses a method for manufacturing a medical elongated body comprising supplying an outer distal shaft, outer proximal shaft, an inner shaft, a first mandrel to be disposed in a lumen of the inner shaft, and a second mandrel to be disposed in a lumen of the outer distal shaft and a lumen of the outer proximal shaft; the method involving disposing a heat shrinkable tube so as to cover a distal end of the outer proximal shaft and the inner shaft.

In a procedure using the balloon catheter, an operator such as a physician inserts the guide wire into a lesion area such as a stenosed site formed in a blood vessel. The operator inserts a proximal side of the guide wire into the guide wire lumen from a distal side of the inner shaft, and causes the guide wire to come out from the guide wire lumen through the guide wire port on the proximal side of the inner shaft. The operator guides the balloon of the balloon catheter to the lesion area by moving the balloon catheter along the guide wire.

In the middle of the procedure, the operator moves the guide wire to a proximal side or a distal side in a state where the guide wire is inserted into the guide wire lumen of the balloon catheter, and takes the guide wire out from a proximal opening portion of the inner shaft. When the operator performs such operation, if stress is excessively concentrated in the vicinity of the guide wire port of the inner shaft, there is a potential that the inner shaft of the balloon catheter may be fractured. If the guide wire is caught in a fractured portion (torn-out portion) of the inner shaft, since the operator has difficulties in smoothly moving the guide wire, the operability of the guide wire deteriorates remarkably.

The present invention has been made in light of the problem, and an object of the present invention is to provide a balloon catheter in which the vicinity of the proximal opening portion formed by the inner shaft can be prevented from being fractured and to provide a method for manufacturing a medical elongated body.

According to the present invention, there is provided a balloon catheter including an inner shaft; an outer shaft covering a part of the inner shaft; and a balloon fixed to the inner shaft and the outer shaft. The outer shaft has an outer distal shaft having a lumen, and an outer proximal shaft fixed to a proximal side of the outer distal shaft and having a lumen communicating with the lumen of the outer distal shaft. A distal side of the inner shaft is disposed in the lumen of the outer distal shaft, a proximal side of the inner shaft is disposed on an outer surface of the outer proximal shaft, and the inner shaft forms a proximal opening portion which opens on an outer surface side of the outer proximal shaft. The inner shaft has a first region and a second region disposed on a proximal side of the first region, in a range from a proximal end of the outer distal shaft disposed on the outer surface of the outer proximal shaft to the proximal opening portion. The first region is fixed to the outer surface of the outer proximal shaft. The second region is not fixed to the outer surface of the outer proximal shaft. The outer diameter of the outer proximal shaft is smaller than the outer diameter of the outer distal shaft.

In addition, according to the present invention, there is provided a method for manufacturing a medical elongated body, the method including supplying an outer distal shaft, an outer proximal shaft, an inner shaft, a first mandrel to be disposed in a lumen of the inner shaft, and a second mandrel to be disposed in a lumen of the outer distal shaft and a lumen of the outer proximal shaft; disposing the inner shaft in the lumen of the outer distal shaft; inserting the first mandrel into the lumen of the inner shaft; disposing the outer proximal shaft such that a distal side of the inner shaft is disposed in the lumen of the outer distal shaft and a proximal side of the inner shaft is disposed on an outer surface of the outer proximal shaft; inserting the second mandrel into the lumen of the outer distal shaft and the lumen of the outer proximal shaft; disposing a heat shrinkable tube so as to cover a proximal end of the outer distal shaft, a distal end of the outer proximal shaft, and the inner shaft; positioning a proximal end of the heat shrinkable tube closer to a distal side than a proximal end of the inner shaft; and welding together the outer distal shaft, the outer proximal shaft, and the inner shaft in a state where the heat shrinkable tube is shrunk by applying heat thereto and the proximal end of the inner shaft is not welded by the heat shrinkable tube.

The second region positioned on the proximal side of the inner shaft is not fixed to the outer surface of the outer proximal shaft. Therefore, for example, when the guide wire is being taken out from the proximal opening portion of the inner shaft, the foregoing configuration of the balloon catheter can prevent stress from being concentrated in the vicinity of the proximal opening portion. In the balloon catheter, therefore, the inner shaft can be prevented from being fractured, and a deterioration in the operability of the guide wire can be prevented, which would otherwise be induced by fracturing of the inner shaft. In addition, since the second region positioned on the proximal side of the inner shaft is not fixed to the outer surface of the outer proximal shaft, when the balloon catheter is delivered to a body lumen such as a curved blood vessel, the balloon catheter is easily deformed such that the second region follows the guide wire. Therefore, the balloon catheter improves the followability of the inner shaft with respect to the guide wire.

In the method for manufacturing a medical elongated body, when the inner shaft is being welded to the outer shaft, since the proximal end of the inner shaft is not welded by the heat shrinkable tube, the proximal end of the inner shaft is not fixed to the outer surface of the outer proximal shaft. Therefore, for example, when the guide wire is being taken out from the proximal opening portion of the inner shaft, stress can be prevented from being concentrated in the vicinity of the proximal end of the inner shaft in the medical elongated body manufactured by the manufacturing method. In addition, when being delivered to a body lumen such as a curved blood vessel, the vicinity of the proximal end of the inner shaft is easily deformed to follow the guide wire, so that the inner shaft in the medical elongated body manufactured by the manufacturing method has an improved ability to follow the guide wire.

As illustrated in <FIG>, a balloon catheter <NUM> according to an embodiment is a medical device that widens and treats a lesion area such as a stenosed site formed in a body lumen by inflating a balloon <NUM>, which is disposed on a distal side of a shaft <NUM>, in the lesion area.

The balloon catheter <NUM> is configured as a balloon catheter used in the PTCA treatment which is used to widen a stenosed site in a coronary artery. However, the balloon catheter <NUM> can be also configured as a balloon catheter intended to treat a lesion area such as a stenosed site formed in body organs such as other blood vessels, biliary duct, trachea, esophagus, other digestive tracts, urethra, ear and nose cavity, and other organs.

Hereinbelow, the balloon catheter <NUM> will be described.

As illustrated in <FIG>, the balloon catheter <NUM> has an elongated shaft (equivalent to a "medical elongated body") <NUM>; the balloon <NUM> disposed on the distal side of the shaft <NUM>; and a hub <NUM> disposed on a proximal side of the shaft <NUM>.

In the description of the embodiment, a side on which the balloon <NUM> is disposed refers to a distal side of the balloon catheter <NUM>, a side on which the hub <NUM> is disposed refers to a proximal side of the balloon catheter <NUM>, and a stretching direction of the shaft <NUM> refers to an axial direction. In addition, in the description of the embodiment, a distal portion indicates a certain range containing a distal end (distalmost end) and the vicinity of the distal end, and a proximal portion indicates a certain range containing a proximal end (proximalmost end) and the vicinity of the proximal end.

As illustrated in <FIG>, the balloon catheter <NUM> is configured as a so-called rapid exchange type catheter in which a proximal opening portion (guide wire port) <NUM>, through which a guide wire <NUM> can be inserted and removed, is formed close to the distal side of the shaft <NUM>.

As illustrated in <FIG>, the shaft <NUM> has an outer shaft <NUM> including a lumen (inflation lumen) <NUM>, and an inner shaft <NUM> including a lumen (guide wire lumen) <NUM> which is disposed in the lumen <NUM> of the outer shaft <NUM> and into which the guide wire <NUM> is inserted.

As illustrated in <FIG> and <FIG>, the shaft <NUM> has the proximal opening portion (equivalent to a "proximal opening portion of the inner shaft") <NUM> communicating with the lumen <NUM> of the inner shaft <NUM>. The proximal opening portion <NUM> is formed in the vicinity of a proximal end of the inner shaft <NUM>.

As illustrated in <FIG>, the outer shaft <NUM> has an outer distal shaft <NUM>, and an outer proximal shaft <NUM> fixed to a proximal side of the outer distal shaft <NUM>.

The outer distal shaft <NUM> is formed as a tubular member in which a lumen <NUM> extending in the axial direction is formed. Similarly, the outer proximal shaft <NUM> is formed as a tubular member in which a lumen <NUM> extending in the axial direction is formed.

The outer distal shaft <NUM> and the outer proximal shaft <NUM> are integrally connected (welded) to the inner shaft <NUM> in the vicinity of the proximal opening portion <NUM> of the shaft <NUM>.

As illustrated in <FIG>, the lumen <NUM> of the outer distal shaft <NUM> communicates with the lumen <NUM> of the outer proximal shaft <NUM>. In addition, in a state where the lumen <NUM> of the outer distal shaft <NUM> communicates with the lumen <NUM> of the outer proximal shaft <NUM>, the lumen <NUM> and the lumen <NUM> form the lumen (inflation lumen) <NUM> communicating with an inflation space <NUM> of the balloon <NUM>.

The outer distal shaft <NUM> and the outer proximal shaft <NUM> can be formed of, for example, polyolefin such as polyethylene, polypropylene, ethylene-propylene copolymer, or ethylene-vinyl acetate copolymer, thermoplastic resin such as soft polyvinyl chloride, any of various elastomers such as polyurethane elastomer, polyamide elastomer, and polyester elastomer, polyamide, or crystalline plastic such as polyamide, crystalline polyethylene, or crystalline polypropylene.

As illustrated in <FIG>, a distal side of the inner shaft <NUM> is disposed in the lumen <NUM> of the outer distal shaft <NUM>. A certain range on the distal side of the inner shaft <NUM> is disposed protruding to a distal side of the outer distal shaft <NUM>.

In addition, as illustrated in <FIG>, the inner shaft <NUM> is configured such that a proximal side of the inner shaft <NUM> is disposed on an outer surface of the outer proximal shaft <NUM>. The proximal opening portion <NUM> which opens on an outer surface side of the outer proximal shaft <NUM> is formed on the proximal side of the inner shaft <NUM>. Note that a first region 150A and a second region 150B which will be described later are formed on the proximal side of the inner shaft <NUM>.

As illustrated in <FIG>, the inner shaft <NUM> has a distal member <NUM> disposed on the distal side. The distal member <NUM> has a lumen <NUM> into which the guide wire <NUM> can be inserted.

Since the inner shaft <NUM> includes the distal member <NUM> on the distal side, when a distal end of the balloon catheter <NUM> comes into contact with a body lumen (intravascular wall or the like), the distal end is prevented from causing damages to a body organ. The distal member <NUM> can be formed of, for example, a flexible resin material. However, the material of the distal member <NUM> is not specifically limited if the distal member <NUM> can be fixed to the inner shaft <NUM>.

As illustrated in <FIG>, the lumen <NUM> of the inner shaft <NUM> communicates with the lumen <NUM> of the distal member <NUM> on the distal side of the inner shaft <NUM>. In addition, as illustrated in <FIG>, the lumen <NUM> of the inner shaft <NUM> communicates with the proximal opening portion <NUM> on the proximal side of the inner shaft <NUM>.

The inner shaft <NUM> can be formed of, for example, the same materials as the materials exemplified as the configuration material of the outer shaft <NUM>.

As illustrated in <FIG>, the balloon <NUM> has a distal portion <NUM> fixed to a distal portion of the inner shaft <NUM>; a proximal portion <NUM> fixed to a distal portion of the outer shaft <NUM> (distal portion of the outer distal shaft <NUM>); and an intermediate portion <NUM> that forms a maximum outer diameter portion formed between the distal portion <NUM> of the balloon <NUM> and the proximal portion <NUM> of the balloon <NUM>. In addition, the balloon <NUM> has a distal side tapered portion <NUM> formed between the distal portion <NUM> of the balloon <NUM> and the intermediate portion <NUM> of the balloon <NUM>, and a proximal side tapered portion <NUM> formed between the proximal portion <NUM> of the balloon <NUM> and the intermediate portion <NUM> of the balloon <NUM>.

The balloon <NUM> has the inflation space <NUM> formed between the balloon <NUM> and an outer circumferential surface of the shaft <NUM> and communicating with the lumen <NUM> of the outer shaft <NUM>. If a fluid flows into the inflation space <NUM>, the balloon <NUM> is inflated in a radial direction of the balloon <NUM> which intersects the axial direction.

The balloon <NUM> can be formed of, for example, polyolefin such as polyethylene, polypropylene, or ethylene-propylene copolymer, polyester such as polyethylene terephthalate, thermoplastic resin such as polyvinyl chloride, ethylene-vinyl acetate copolymer, cross-linked ethylene-vinyl acetate copolymer, or polyurethane, polyamide, polyamide elastomer, polystyrene elastomer, silicone rubber, or latex rubber.

As illustrated in <FIG>, the inner shaft <NUM> has a contrast marker <NUM> indicating substantially an axially central position of the intermediate portion <NUM> of the balloon <NUM>. The contrast marker <NUM> can be formed of, for example, metal such as platinum, gold, silver, iridium, titanium, or tungsten, or alloys thereof. Note that the contrast marker <NUM> may be disposed at a position indicating a boundary portion between the distal side tapered portion <NUM> and the intermediate portion <NUM> in the inner shaft <NUM>, or at a position indicating a boundary portion between the proximal side tapered portion <NUM> and the intermediate portion <NUM> in the inner shaft <NUM>.

As illustrated in <FIG>, the hub <NUM> has a port <NUM> that can be liquid-tightly and air-tightly connected to a supply device (not illustrated) such as an indeflator for supplying a fluid (for example, contrast agent or physiological salt solution). For example, the port <NUM> of the hub <NUM> can be configured as a well-known Lure taper or the like which is configured such that a tube or the like can be connected to and detached therefrom.

Subsequently, the inner shaft <NUM> will be described in detail.

As illustrated in <FIG> and <FIG>, the inner shaft <NUM> has the first region 150A, and the second region 150B disposed on a proximal side of the first region 150A. Note that <FIG> is an enlarged cross-sectional view (enlarged cross-sectional view of the inner shaft <NUM> in the axial direction) of a portion 3A surrounded by the broken line illustrated in <FIG>.

As illustrated in <FIG>, the first region 150A is a region where the inner shaft <NUM> and the outer proximal shaft <NUM> are fixed (welded) together in a range from a proximal end <NUM> of the outer distal shaft <NUM> to the proximal opening portion <NUM> of the inner shaft <NUM> (in an axial range from the proximal end <NUM> of the outer distal shaft <NUM> to a proximal end of the proximal opening portion <NUM> of the inner shaft <NUM>). In addition, the second region 150B is a region where the inner shaft <NUM> and the outer proximal shaft <NUM> are not fixed (welded) together in the range from the proximal end <NUM> of the outer distal shaft <NUM> to the proximal opening portion <NUM> of the inner shaft <NUM>.

As will be described later in a method for manufacturing the shaft <NUM>, the first region 150A is formed in a region where a heat shrinkable tube <NUM> is disposed in the inner shaft <NUM> when welding together the shafts <NUM>, <NUM>, and <NUM>. In addition, the second region 150B is formed in a region located farther to the proximal side than the region where the heat shrinkable tube <NUM> is disposed in the inner shaft <NUM> (refer to <FIG>).

As illustrated in <FIG>, the inner shaft <NUM> has an inclined portion <NUM> inclined from the first region 150A to the second region 150B. In addition, the proximal opening portion <NUM> of the inner shaft <NUM> is formed in the inclined portion <NUM>.

As illustrated in <FIG>, in an axial cross-section of the inner shaft <NUM>, the proximal opening portion <NUM> of the inner shaft <NUM> is inclined from the proximal side of the inner shaft <NUM> to the distal side. Since the proximal opening portion <NUM> is formed in the inclined portion <NUM>, the proximal opening portion <NUM> and the inclined portion <NUM> are disposed on the same plane.

Note that the inclined angle of the inclined portion <NUM> inclined with respect to the axial direction is not specifically limited. In addition, the proximal opening portion <NUM> may not be formed in the inclined portion <NUM>, but instead, for example, may be formed in such a way that the proximal opening portion <NUM> opens substantially perpendicular to the axial direction of the inner shaft <NUM>.

As illustrated in <FIG>, the proximal opening portion <NUM> of the inner shaft <NUM> has a non-fixed portion <NUM> at the position of the second region 150B facing the outer surface of the outer proximal shaft <NUM>. Note that <FIG> is an arrow view of the inner shaft <NUM> taken in the direction of an arrow head 4A illustrated in <FIG>.

The non-fixed portion <NUM> is formed in a proximal portion of a peripheral edge portion 105a of the proximal opening portion <NUM>. In addition, the non-fixed portion <NUM> forms a flat portion 147a in the peripheral edge portion 105a of the proximal opening portion <NUM>.

In the arrow view illustrated in <FIG>, the flat portion 147a is formed at a proximal end of the peripheral edge portion 105a of the proximal opening portion <NUM> and in the vicinity of the proximal end such that the flat portion 147a is continuous with an inner surface of the inner shaft <NUM>. The flat portion 147a is formed such that a width W1 of the flat portion 147a along the axial direction of the inner shaft <NUM> is longer than the width of an opposite portion <NUM> (which will be described later) (region formed at a distal end of the peripheral edge portion 105a of the proximal opening portion <NUM> and in the vicinity of the distal end), and a distance L1 of the flat portion 147a in a direction perpendicular to the axial direction of the inner shaft <NUM> is longer than the distance of the opposite portion <NUM> (which will be described later) (region formed at the distal end of the peripheral edge portion 105a of the proximal opening portion <NUM> and in the vicinity of the distal end). Therefore, since the flat portion 147a is formed in a region in the peripheral edge portion 105a of the proximal opening portion <NUM>, in which the thickness of the inner shaft <NUM> is large and the circumferential length of the inner shaft <NUM> is long, even though the non-fixed portion <NUM> is excessively bent due to being aligned with the guide wire inserted into the lumen <NUM> of the inner shaft <NUM>, it is possible to restrain the non-fixed portion <NUM> from being bent and improve the operability of the guide wire operated by an operator. As will be described later, it is possible to form the flat portion 147a by adjusting a cut angle (cut direction) of the inner shaft <NUM> and cutting away the proximal end of the peripheral edge portion 105a of the proximal opening portion <NUM> when forming the proximal opening portion <NUM> and the inclined portion <NUM> of the inner shaft <NUM> (refer to <FIG>).

As illustrated in <FIG>, the flat portion 147a is formed such that a thickness t1 of the flat portion 147a decreases from the distal side toward the proximal side in the axial direction. The thickness t1 of the flat portion 147a decreases gradually toward the proximal side along an inclined direction of the inclined portion <NUM>, and becomes minimum at the proximal end of the peripheral edge portion 105a of the proximal opening portion <NUM>.

As illustrated in <FIG>, the proximal opening portion <NUM> includes the opposite portion <NUM> that is opposite to the non-fixed portion <NUM> in a state where the lumen <NUM> (or the proximal opening portion <NUM>) of the inner shaft <NUM> is interposed therebetween, and a pair of side wall portions 149a and 149b at positions intersecting a direction (rightward and leftward direction in <FIG>) along which the non-fixed portion <NUM> is connected to the opposite portion <NUM>.

As illustrated in <FIG>, in the proximal opening portion <NUM>, the thickness of each of the side wall portions 149a and 149b increases from the opposite portion <NUM> toward the flat portion 147a. For this reason, as illustrated in <FIG>, in the proximal opening portion <NUM>, a width W2 (refer to <FIG>) of each of the side wall portions 149a and 149b increases from the opposite portion <NUM> toward the flat portion 147a.

As will be described later, the opposite portion <NUM> is formed in a portion covered with the heat shrinkable tube <NUM> when the shafts <NUM>, <NUM>, and <NUM> are welded together. In addition, when the shafts <NUM>, <NUM>, and <NUM> are to be welded together, at least part of each of the side wall portions 149a and 149b is disposed closer to the proximal side than a proximal end <NUM> of the heat shrinkable tube <NUM> (refer to <FIG>). Herein, heat applied to the heat shrinkable tube <NUM> affects a certain range closer to the proximal side than the proximal end <NUM> of the heat shrinkable tube <NUM>. For this reason, a portion of the inner shaft <NUM> in which each of the side wall portions 149a and 149b is formed has a thickness after welding and the width W2 which increase from the distal side relatively highly affected by heat applied to the heat shrinkable tube <NUM> toward the proximal side not much affected by heat. Therefore, as illustrated in <FIG>, the proximal opening portion <NUM> is formed such that the thickness and the width W2 increase from the opposite portion <NUM> toward the flat portion 147a.

As illustrated in <FIG>, in an axial cross-section of the inner shaft <NUM>, an axial length L2 of the second region 150B of the inclined portion <NUM> is shorter than an axial length L3 of the first region 150A of the inclined portion <NUM>.

The axial length of the second region 150B of the inclined portion <NUM> can be set, for example, from <NUM> to <NUM>, and the axial length of the first region 150A of the inclined portion <NUM> can be set, for example, from <NUM> to <NUM>.

As illustrated in <FIG>, the outer distal shaft <NUM> has a large diameter portion <NUM> formed having a predetermined outer diameter D1. In addition, an outer diameter (maximum outer diameter formed by the outer shaft <NUM> and the inner shaft <NUM> at a portion corresponding to the first region 150A and the second region 150B) D2 formed by the outer shaft <NUM> and the inner shaft <NUM> at a portion corresponding to the first region 150A and the second region 150B is smaller than the outer diameter D1 of the large diameter portion <NUM>.

As will be described later, when the shafts <NUM>, <NUM>, and <NUM> are welded together (refer to <FIG>), a predetermined range of the shafts <NUM>, <NUM>, and <NUM> are covered with the heat shrinkable tube <NUM>. If heat is applied to the shafts <NUM>, <NUM>, and <NUM> in this state, a range of the shafts <NUM>, <NUM>, and <NUM> covered with the heat shrinkable tube <NUM> shrink radially inward (in a direction toward the inside of the shaft <NUM>). At that time, a range of the outer distal shaft <NUM> which is not affected by heat maintains a constant outer diameter before and after welding. As illustrated in <FIG>, a portion of the outer distal shaft <NUM>, which maintains the constant outer diameter before and after welding, forms the large diameter portion <NUM>. A portion of the outer distal shaft <NUM> which has an outer diameter decreased after the shafts <NUM>, <NUM>, and <NUM> are welded together, namely, the portion covered with the heat shrinkable tube <NUM> when the shafts <NUM>, <NUM>, and <NUM> are being welded together forms a small diameter portion <NUM> having an outer diameter smaller than the outer diameter of the large diameter portion <NUM>. In addition, a boundary portion <NUM> is formed between the large diameter portion <NUM> and the small diameter portion <NUM>, and heat applied to the heat shrinkable tube <NUM> causes the outer diameter of the boundary portion <NUM> to increase gradually from the small diameter portion <NUM> toward the large diameter portion <NUM>.

Subsequently, the method for manufacturing the shaft (medical elongated body) <NUM> will be described with reference to <FIG>.

Firstly, a worker manufacturing the shaft <NUM> supplies (prepares) the outer distal shaft <NUM>, the outer proximal shaft <NUM>, the inner shaft <NUM>, a first mandrel <NUM> to be disposed in the lumen <NUM> of the inner shaft <NUM>, and a second mandrel <NUM> to be disposed in the lumen <NUM> of the outer distal shaft <NUM> and the lumen <NUM> of the outer proximal shaft <NUM>.

As the outer distal shaft <NUM>, for example, the worker prepares a tubular member having an outer diameter and an inner diameter which are substantially constant in an axial direction. In addition, as the outer proximal shaft <NUM>, for example, the worker prepares a tubular member, the distal end of which is obliquely inclined from a distal side toward a proximal side, and in which a portion other than the distal end has an outer diameter and an inner diameter which are substantially constant in an axial direction. In addition, as the inner shaft <NUM>, for example, the worker prepares a tubular member having an outer diameter and an inner diameter which are substantially constant in an axial direction, and in which an opening portion 143a is formed in a proximal end <NUM> (refer to <FIG> for an example of the shape of each of the shafts <NUM>, <NUM>, and <NUM>).

As each of the first mandrel <NUM> and the second mandrel <NUM>, for example, the worker may use a well-known mandrel that extends substantially straight in an axial direction.

As illustrated in <FIG>, the worker disposes the inner shaft <NUM> in the lumen <NUM> of the outer distal shaft <NUM>. At that time, the worker disposes the inner shaft <NUM> such that the proximal side of the inner shaft <NUM> protrudes by a predetermined range from the proximal end <NUM> of the outer distal shaft <NUM>.

Subsequently, as illustrated in <FIG>, the worker inserts the first mandrel <NUM> into the lumen <NUM> of the inner shaft <NUM>. The first mandrel <NUM> is disposed such that a proximal side of the first mandrel <NUM> protrudes from the opening portion 143a of the inner shaft <NUM>.

Subsequently, as illustrated in <FIG>, the worker disposes the outer proximal shaft <NUM> such that the distal side of the inner shaft <NUM> is disposed in the lumen <NUM> of the outer distal shaft <NUM> and the proximal side of the inner shaft <NUM> is disposed on the outer surface of the outer proximal shaft <NUM>.

Subsequently, as illustrated in <FIG>, the worker inserts the second mandrel <NUM> into the lumen <NUM> of the outer distal shaft <NUM> and the lumen <NUM> of the outer proximal shaft <NUM>.

Note that the worker may perform, in random order, the operation of disposing the inner shaft <NUM> in the lumen <NUM> of the outer distal shaft <NUM>, the operation of disposing the first mandrel <NUM> in the inner shaft <NUM>, the operation of disposing the outer proximal shaft <NUM> in the outer distal shaft <NUM>, and the operation of inserting the second mandrel <NUM> into the lumen <NUM> of the outer distal shaft <NUM> and the lumen <NUM> of the outer proximal shaft <NUM>.

Subsequently, as illustrated in <FIG>, the worker disposes the heat shrinkable tube <NUM> so as to cover the proximal end <NUM> of the outer distal shaft <NUM>, a distal end <NUM> of the outer proximal shaft <NUM>, and the inner shaft <NUM>. At that time, the worker disposes the proximal end <NUM> of the heat shrinkable tube <NUM> closer to the distal side in the axial direction than the proximal end <NUM> of the inner shaft <NUM>, and disposes a distal end <NUM> of the heat shrinkable tube <NUM> closer to the distal side in the axial direction than the proximal end <NUM> of the outer distal shaft <NUM> and the distal end <NUM> of the outer proximal shaft <NUM>.

As the heat shrinkable tube <NUM>, for example, the worker may use a hollow cylindrical member formed of polyolefin or the like.

Subsequently, the worker causes the heat shrinkable tube <NUM> to shrink by applying heat thereto, and welds together the outer distal shaft <NUM>, the outer proximal shaft <NUM>, and the inner shaft <NUM> in a state where the proximal end <NUM> of the inner shaft <NUM> is not welded by the heat shrinkable tube <NUM>. If the heat shrinkable tube <NUM> is heated, the heat shrinkable tube <NUM> shrinks and is deformed such that the inner diameter of the heat shrinkable tube <NUM> after being heated becomes smaller than the inner diameter of the heat shrinkable tube <NUM> before being heated.

The worker welds together the shafts <NUM>, <NUM>, and <NUM> by causing the heat shrinkable tube <NUM> to shrink, so that as illustrated in <FIG>, the first region 150A and the second region 150B are formed in the inner shaft <NUM>.

As illustrated in <FIG>, since the first region 150A positioned closer to the proximal side than the proximal end <NUM> of the heat shrinkable tube <NUM> is affected by heat applied to the heat shrinkable tube <NUM> when the shafts <NUM>, <NUM>, and <NUM> are being welded together, the first region 150A has a cross-sectional shape, the thickness of which increases gradually from the distal side toward the proximal side. In addition, since the vicinity of the proximal end <NUM> of the inner shaft <NUM> is not hardly affected by heat applied to the heat shrinkable tube <NUM>, the thickness is maintained substantially constant before and after welding.

Similar to the inner shaft <NUM>, since a portion of the outer proximal shaft <NUM> positioned in the vicinity of the proximal end <NUM> of the heat shrinkable tube <NUM> is affected by heat applied to the heat shrinkable tube <NUM>, the outer proximal shaft <NUM> has such cross-sectional shape that the thickness of the portion increases from the distal side toward the proximal side. In addition, the thickness of a portion of the outer proximal shaft <NUM>, which is spaced apart by a predetermined distance from the proximal end <NUM> of the heat shrinkable tube <NUM> toward the proximal side, is maintained substantially constant before and after welding.

As illustrated in <FIG>, after welding, the small diameter portion <NUM> is formed in a portion of the outer distal shaft <NUM> which is covered with the heat shrinkable tube <NUM>, the boundary portion <NUM> is formed in a portion (positioned closer to the distal side than the small diameter portion <NUM>) thereof which is not covered with the heat shrinkable tube <NUM>, and the large diameter portion <NUM> is formed on a distal side of the boundary portion <NUM>.

After the shafts <NUM>, <NUM>, and <NUM> are welded together, the worker pulls the first mandrel <NUM> out from the lumen <NUM> of the inner shaft <NUM>. For example, in random order, the worker may pull the second mandrel <NUM> out from the lumen <NUM> of the outer distal shaft <NUM> and the lumen <NUM> of the outer proximal shaft <NUM>, and pulling the first mandrel <NUM> out from the lumen <NUM> of the inner shaft <NUM>. Note that in the illustrated example, the worker pulls out the mandrels <NUM> and <NUM> after welding.

Subsequently, as illustrated in <FIG>, the worker obliquely cuts a proximal portion (certain range on the proximal side containing the proximal end <NUM>) of the inner shaft <NUM> across the first region 150A of the inner shaft <NUM> and the second region 150B of the inner shaft <NUM> (example of a cut position illustrated by a broken line c1 of <FIG>). Note that before obliquely cutting the proximal portion of the inner shaft <NUM> (certain range on the proximal side containing the proximal end <NUM>) across the first region 150A of the inner shaft <NUM> and the second region 150B of the inner shaft <NUM>, the worker pulls out the heat shrinkable tube <NUM>. <FIG> is an enlarged cross-sectional view of a portion surrounded by a broken line portion 7A of <FIG>, and a view for describing the cut position.

Since the worker cuts the inner shaft <NUM> as described above, the inclined portion <NUM> inclined from the first region 150A of the inner shaft <NUM> toward the second region 150B of the inner shaft <NUM> is formed (refer to <FIG>). At that time, the worker cuts the inner shaft <NUM> such that the axial length L2 of the second region 150B of the inclined portion <NUM> is shorter than the axial length L3 of the first region 150A of the inclined portion <NUM> (refer to <FIG>).

Since the worker cuts the inner shaft <NUM> as described above, the proximal opening portion <NUM> is formed in the inner shaft <NUM> (refer to <FIG>). In addition, at that time, the worker forms the non-fixed portion <NUM>, which is not fixed to the outer proximal shaft <NUM>, in the peripheral edge portion 105a of the proximal opening portion <NUM> of the inner shaft <NUM> (refer to <FIG>).

In addition, since the worker cuts the inner shaft <NUM> as described above, as illustrated in <FIG>, the flat portion 147a is formed in the non-fixed portion <NUM> positioned in the second region 150B, the opposite portion <NUM> is formed in the peripheral edge portion 105a of the proximal opening portion <NUM> at a position opposite to the non-fixed portion <NUM> in a state where the lumen <NUM> is interposed between the opposite portion <NUM> and the non-fixed portion <NUM>, and the side wall portions 149a and 149b are formed connecting the opposite portion <NUM> to the non-fixed portion <NUM>.

Each of the side wall portions 149a and 149b is formed across the first region 150A and the second region 150B of the inner shaft <NUM>. In addition, each of the side wall portions 149a and 149b of the proximal opening portion <NUM> of the inner shaft <NUM> has the thickness and the width W2 illustrated in <FIG> which increase from the opposite portion <NUM> toward the flat portion 147a.

It is possible to cut the inner shaft <NUM> using a well-known tool provided with a blade capable of cutting the inner shaft <NUM>.

Note that the cut position or the cut angle (cut direction) of the inner shaft <NUM> is not specifically limited. In the embodiment, the inner shaft <NUM> is cut at a predetermined position where the flat portion 147a is formed in the peripheral edge portion 105a of the proximal opening portion <NUM>, and at a predetermined angle. However, for example, the worker may cut the inner shaft <NUM> substantially perpendicular to the axial direction of the inner shaft <NUM> such that the proximal opening portion <NUM> of the inner shaft <NUM> does not have an inclined cross-sectional shape.

The worker may execute each step described above to manufacture the shaft <NUM> including the inner shaft <NUM> in which the first region 150A and the second region 150B are formed, and the outer shaft <NUM> formed by the outer distal shaft <NUM> and the outer proximal shaft <NUM>.

Subsequently, effects of the balloon catheter <NUM> and effects of the method for manufacturing the shaft <NUM> according to the embodiment will be described.

The balloon catheter <NUM> according to the embodiment includes the inner shaft <NUM>; the outer shaft <NUM> covering part of the inner shaft <NUM>; and the balloon <NUM> fixed to the inner shaft <NUM> and the outer shaft <NUM>. The outer shaft <NUM> has the outer distal shaft <NUM> having the lumen <NUM>, and the outer proximal shaft <NUM> fixed to the proximal side of the outer distal shaft <NUM> and having the lumen <NUM> communicating with the lumen <NUM> of the outer distal shaft <NUM>. In addition, the distal side of the inner shaft <NUM> is disposed in the lumen <NUM> of the outer distal shaft <NUM>, and the proximal side of the inner shaft <NUM> is disposed on the outer surface of the outer proximal shaft <NUM>. The inner shaft <NUM> forms the proximal opening portion <NUM> which opens on the outer surface side of the outer proximal shaft <NUM>. The inner shaft <NUM> has the first region 150A and the second region 150B disposed on the proximal side of the first region 150A, in the range from the proximal end <NUM> of the outer distal shaft <NUM> disposed on the outer surface of the outer proximal shaft <NUM> to the proximal opening portion <NUM> of the inner shaft <NUM>. The first region 150A is fixed to the outer surface of the outer proximal shaft <NUM>, and the second region 150B is not fixed to the outer surface of the outer proximal shaft <NUM>.

Since the second region 150B positioned on the proximal side of the inner shaft <NUM> is not fixed to the outer surface of the outer proximal shaft <NUM>, for example, when the guide wire <NUM> is being taken out from the proximal opening portion (guide wire port) <NUM> of the inner shaft <NUM>, the foregoing configuration of the balloon catheter <NUM> can prevent stress from being concentrated in the vicinity of the proximal opening portion <NUM>. In the balloon catheter <NUM>, therefore, the inner shaft <NUM> can be prevented from being fractured, and a deterioration in the operability of the guide wire <NUM> can be prevented, which would otherwise be induced by fracturing of the inner shaft <NUM>. In addition, since the second region 150B positioned on the proximal side of the inner shaft <NUM> is not fixed to the outer surface of the outer proximal shaft <NUM>, when the balloon catheter <NUM> is delivered to a body lumen such as a curved blood vessel, the balloon catheter <NUM> is easily deformed such that the second region 150B follows the guide wire <NUM>. Therefore, in the balloon catheter <NUM>, the followability of the inner shaft <NUM> with respect to the guide wire <NUM> improves.

In addition, the inner shaft <NUM> of the balloon catheter <NUM> has the inclined portion <NUM> inclined from the first region 150A toward the second region 150B. The proximal opening portion <NUM> is formed in the inclined portion <NUM>. For this reason, in the balloon catheter <NUM>, the proximal opening portion <NUM> can be formed having a larger opening area compared to when the proximal opening portion <NUM> of the inner shaft <NUM> opens perpendicular to the axial direction of the inner shaft <NUM>. Therefore, an operator can easily take out the guide wire <NUM> through the proximal opening portion <NUM> of the balloon catheter <NUM>.

In addition, the proximal opening portion <NUM> of the balloon catheter <NUM> has the non-fixed portion <NUM> at the position of the second region 150B facing the outer surface of the outer proximal shaft <NUM>. The non-fixed portion <NUM> forms the flat portion 147a in the peripheral edge portion 105a of the proximal opening portion <NUM>. For this reason, the flat portion 147a improves the kink resistance of the non-fixed portion <NUM>. Therefore, even though the non-fixed portion <NUM> is excessively bent when aligned with the guide wire <NUM> inserted into the lumen <NUM> of the inner shaft <NUM>, bending of the non-fixed portion <NUM> can be limited in the balloon catheter <NUM>. For this reason, when the guide wire <NUM> is taken out through the proximal opening portion <NUM> of the inner shaft <NUM>, the balloon catheter <NUM> can prevent a coil portion or the like of the guide wire <NUM> from being caught at the proximal end of the proximal opening portion <NUM>. Therefore, the operator can easily and smoothly take the guide wire <NUM> out from the proximal opening portion <NUM> of the inner shaft <NUM>.

In addition, the thickness of the flat portion 147a of the inner shaft <NUM> of the balloon catheter <NUM> decreases from the distal side toward the proximal side. In such configuration, the inner shaft <NUM> is fixed to the outer shaft <NUM> at a position closer to the distal side than the portion of the inner shaft <NUM> in which the flat portion 147a is formed. Namely, in the inner shaft <NUM>, a proximal end (portion having the smallest thickness in the peripheral edge portion 105a of the proximal opening portion <NUM>) of the flat portion 147a formed in the peripheral edge portion 105a of the proximal opening portion <NUM> of the inner shaft <NUM> is not fixed to the outer shaft <NUM>. In the inner shaft <NUM>, therefore, stress can be prevented from being concentrated at the proximal end of the flat portion 147a, and the occurrence of fracture can be advantageously prevented, which would otherwise be induced by stress concentrated on a portion of the inner shaft <NUM> which is positioned closer to the distal side than the flat portion 147a and has a relatively large thickness.

In addition, the proximal opening portion <NUM> of the inner shaft <NUM> of the balloon catheter <NUM> includes the opposite portion <NUM> that is opposite to the non-fixed portion <NUM> in a state where the lumen <NUM> of the inner shaft <NUM> is interposed therebetween, and the side wall portions 149a and 149b formed at the positions intersecting the direction along which the non-fixed portion <NUM> is connected to the opposite portion <NUM>. The thickness of each of the side wall portions 149a and 149b increases from the opposite portion <NUM> toward the flat portion 147a.

In the balloon catheter <NUM> with the foregoing configuration, the thickness of each of the side wall portions 149a and 149b increases toward a proximal side of the peripheral edge portion 105a of the proximal opening portion <NUM>. For this reason, in the balloon catheter <NUM>, it is possible to reinforce the peripheral edge portion 105a of the proximal opening portion <NUM> of the inner shaft <NUM> by increasing the thickness of a portion of each of the side wall portions 149a and 149b in a region, which is positioned closer to the distal side than the non-fixed portion <NUM> of the inner shaft <NUM>. Therefore, when stress is concentrated on the portion of each of the side wall portions 149a and 149b of the inner shaft <NUM>, which is positioned closer to the distal side than the non-fixed portion <NUM>, the balloon catheter <NUM> can prevent the inner shaft <NUM> from being fractured in the vicinity of the peripheral edge portion 105a of the proximal opening portion <NUM>. Note that if the proximal opening portion <NUM> is formed by the inclined portion <NUM>, a cross section of the proximal portion of the inner shaft <NUM> which is perpendicular to the axial direction of the inner shaft <NUM> has an area decreasing from the distal side toward the proximal side. For this reason, in the balloon catheter <NUM>, it is possible to increase the opening area of the proximal opening portion <NUM> and to reinforce the peripheral edge portion 105a of the proximal opening portion <NUM> of the inner shaft <NUM> by increasing the thickness of the portion of each of the side wall portions 149a and 149b, which is closer to the distal side than the non-fixed portion <NUM> of the inner shaft <NUM>.

In addition, in the axial cross-section of the inner shaft <NUM>, the axial length of the second region 150B of the inclined portion <NUM> of the balloon catheter <NUM> is shorter than the axial length of the first region 150A of the inclined portion <NUM>.

In the balloon catheter <NUM> with the foregoing configuration, in a large range of the inclined portion <NUM>, the inner shaft <NUM> is in contact with the outer shaft <NUM> in the axial direction. For this reason, the balloon catheter <NUM> can have an increased fixing force between the inner shaft <NUM> and the outer shaft <NUM> in the inclined portion <NUM>, and reduce the concentration of stress on the peripheral edge portion 105a of the proximal opening portion <NUM> of the inner shaft <NUM> by virtue of the non-fixed portion <NUM>. For example, when the guide wire <NUM> comes into contact with the opposite portion <NUM> of the inner shaft <NUM>, the balloon catheter <NUM> can reduce the concentration of stress between the proximal portion of the inner shaft <NUM> and the outer proximal shaft <NUM> by virtue of the non-fixed portion <NUM>. Therefore, when stress is concentrated in the vicinity of the proximal opening portion <NUM> of the inner shaft <NUM>, the balloon catheter <NUM> can more advantageously prevent the inner shaft <NUM> or the outer proximal shaft <NUM> from being fractured in the vicinity of the proximal opening portion <NUM>.

In addition, the outer distal shaft <NUM> of the balloon catheter <NUM> has the large diameter portion <NUM> formed having the predetermined outer diameter, and the outer diameter formed by the outer shaft <NUM> and the inner shaft <NUM> at the portion corresponding to the first region 150A and the second region 150B is smaller than the outer diameter of the large diameter portion <NUM>.

When inserting the balloon catheter <NUM> into a body lumen such as a blood vessel, the operator or the like may insert another medical device (for example, a balloon catheter separate from the balloon catheter or a catheter device used in image diagnosis) together with the balloon catheter <NUM> using one catheter (well-known guiding catheter or the like). At that time, if the outer diameter of the vicinity of the proximal opening portion <NUM> of the balloon catheter <NUM> is excessively large, the balloon catheter <NUM> may interfere with the other medical devices inside the catheter, and the smooth movement of both may be interrupted. As described above, since the outer diameter formed by the outer shaft <NUM> and the inner shaft <NUM> at the portion corresponding to the first region 150A and the second region 150B is smaller than the outer diameter of the large diameter portion <NUM> of the outer distal shaft <NUM>, it is possible to suitably prevent the balloon catheter <NUM> from interfering with the other medical device in a lumen of the catheter.

The method for manufacturing the shaft <NUM> according to the embodiment supplies the outer distal shaft <NUM>, the outer proximal shaft <NUM>, the inner shaft <NUM>, the first mandrel <NUM> to be disposed in the lumen <NUM> of the inner shaft <NUM>, and the second mandrel <NUM> to be disposed in the lumen <NUM> of the outer distal shaft <NUM> and the lumen <NUM> of the outer proximal shaft <NUM>. In addition, in the manufacturing method, the inner shaft <NUM> is disposed in the lumen <NUM> of the outer distal shaft <NUM>, the first mandrel <NUM> is inserted into the lumen <NUM> of the inner shaft <NUM>, the outer proximal shaft <NUM> is disposed such that the distal side of the inner shaft <NUM> is disposed in the lumen <NUM> of the outer distal shaft <NUM> and the proximal side of the inner shaft <NUM> is disposed on the outer surface of the outer proximal shaft <NUM>, the second mandrel <NUM> is inserted into the lumen <NUM> of the outer distal shaft <NUM> and the lumen <NUM> of the outer proximal shaft <NUM>, the heat shrinkable tube <NUM> is disposed so as to cover the proximal end <NUM> of the outer distal shaft <NUM>, the distal end <NUM> of the outer proximal shaft, and the inner shaft <NUM>, and the proximal end <NUM> of the heat shrinkable tube <NUM> is positioned closer to the distal side than the proximal end <NUM> of the inner shaft <NUM>. The manufacturing method contains welding together the outer distal shaft <NUM>, the outer proximal shaft <NUM>, and the inner shaft <NUM> in a state where the heat shrinkable tube <NUM> is shrunk by applying heat thereto and the proximal end <NUM> of the inner shaft <NUM> is not welded by the heat shrinkable tube <NUM>.

In the method for manufacturing the shaft <NUM>, when the inner shaft <NUM> is being welded to the outer shaft <NUM>, since the proximal end <NUM> of the inner shaft <NUM> is not welded by the heat shrinkable tube <NUM>, the proximal end <NUM> of the inner shaft <NUM> is not fixed to the outer surface of the outer proximal shaft <NUM>. Therefore, for example, when the guide wire <NUM> is being taken out from the proximal opening portion <NUM> of the inner shaft <NUM>, the shaft <NUM> manufactured by the manufacturing method can prevent stress from being concentrated in the vicinity of the proximal end <NUM> of the inner shaft <NUM>. In addition, when being delivered to a body lumen such as a curved blood vessel, the vicinity of the proximal end <NUM> of the inner shaft <NUM> is easily deformed to follow the guide wire <NUM>. In the shaft <NUM> manufactured by the manufacturing method, therefore, the inner shaft <NUM> can have an improved ability to follow the guide wire <NUM>.

In addition, in the method for manufacturing the shaft <NUM>, after the outer distal shaft <NUM>, the outer proximal shaft <NUM>, and the inner shaft <NUM> are welded together, the inner shaft <NUM> has the first region 150A in which the inner shaft <NUM> is welded to the outer proximal shaft <NUM>, and the second region 150B which is disposed on the proximal side of the first region 150A and in which the inner shaft <NUM> is not welded to the outer proximal shaft <NUM>, in a range from the proximal end <NUM> of the outer distal shaft <NUM> disposed in an outer surface of the outer shaft <NUM> to the proximal end <NUM> of the inner shaft <NUM>. The manufacturing method contains obliquely cutting the proximal portion of the inner shaft <NUM> across the first region 150A and the second region 150B to form the inclined portion <NUM> inclined from the first region 150A toward the second region 150B.

In the method for manufacturing the shaft <NUM>, the proximal end <NUM> of the inner shaft <NUM> is obliquely cut across the first region 150A and the second region 150B to form the inclined portion <NUM> inclined from the first region 150A toward the second region 150B. Moreover, in the manufacturing method, the proximal opening portion <NUM> of the inner shaft <NUM> is formed across the first region 150A of the inner shaft <NUM> and the second region 150B of the inner shaft <NUM>. In the shaft <NUM> manufactured by the manufacturing method, the opening area of the proximal opening portion <NUM> is larger compared to when the proximal opening portion <NUM> of the inner shaft <NUM> opens perpendicular to the axial direction of the inner shaft <NUM>, and thus the operator can easily take out the guide wire <NUM> through the proximal opening portion <NUM> of the balloon catheter <NUM>. In addition, since the proximal end of the proximal opening portion <NUM> is contained in the second region 150B where the inner shaft <NUM> is not fixed to the outer shaft <NUM>, the shaft <NUM> can prevent stress from being concentrated at the proximal end of the proximal opening portion <NUM> of the inner shaft <NUM>. Therefore, the shaft <NUM> can advantageously prevent the fracturing of the vicinity of the proximal opening portion <NUM> of the inner shaft <NUM>, which would otherwise be induced by the concentration of stress.

In addition, the method for manufacturing the shaft <NUM> contains pulling the first mandrel <NUM> out from the lumen <NUM> of the inner shaft <NUM> before cutting the proximal portion of the inner shaft <NUM>. For this reason, in the manufacturing method, when cutting the inner shaft <NUM>, it is possible to prevent the first mandrel <NUM> from interrupting the smooth progress of the cutting operation. Therefore, a worker manufacturing the shaft <NUM> can easily cut the proximal portion of the inner shaft <NUM> into a predetermined shape across the first region 150A and the second region 150B.

In addition, in the method for manufacturing the shaft <NUM>, when the inclined portion <NUM> inclined from the first region 150A toward the second region 150B is formed by cutting the proximal portion of the inner shaft <NUM>, the inner shaft <NUM> is cut such that in the axial cross-section of the inner shaft <NUM>, the axial length of the second region 150B of the inclined portion <NUM> is shorter than the axial length of the first region 150A of the inclined portion <NUM>.

In the shaft <NUM> manufactured by the method for manufacturing the shaft <NUM>, in a large range of the first region 150A, the inclined portion <NUM> of the inner shaft <NUM> is in contact with the outer shaft <NUM> in the axial direction. For this reason, the balloon catheter <NUM> can have an increased fixing force between the inner shaft <NUM> and the outer shaft <NUM> in the inclined portion <NUM>, and reduce the concentration of stress on the peripheral edge portion 105a of the proximal opening portion <NUM> of the inner shaft <NUM> by virtue of the non-fixed portion <NUM>. For example, when the guide wire <NUM> comes into contact with the opposite portion <NUM> of the inner shaft <NUM>, the balloon catheter <NUM> can reduce the concentration of stress between the proximal portion of the inner shaft <NUM> and the outer proximal shaft <NUM> by virtue of the non-fixed portion <NUM>. Therefore, when stress is concentrated in the vicinity of the proximal opening portion <NUM> of the inner shaft <NUM>, the shaft <NUM> can more advantageously prevent the inner shaft <NUM> or the outer proximal shaft <NUM> from being fractured in the vicinity of the proximal opening portion <NUM>.

The balloon catheter and the method for manufacturing a medical elongated body of the present invention have been described above according to the embodiment. However, various modifications based on the claims can be made to the present invention, and the present invention is not limited only to the content of the embodiment which has been described.

For example, appropriate changes can be made to the structure, the disposition of the members, and the like of the balloon catheter which have been described in the embodiment and the like. Additional members described with reference to the drawings can be omitted, and other additional members which have not been described can be appropriately used. Similarly, appropriate changes can be made also to each step of the method for manufacturing a medical elongated body, the manufacturing instruments used, and the like.

Claim 1:
A balloon catheter (<NUM>) comprising:
an inner shaft (<NUM>);
an outer shaft (<NUM>) covering a part of the inner shaft (<NUM>); and
a balloon (<NUM>) fixed to the inner shaft (<NUM>) and the outer shaft (<NUM><NUM>), wherein
the outer shaft (<NUM>) has an outer distal shaft (<NUM>) having a lumen (<NUM>), and an outer proximal shaft (<NUM>) fixed to a proximal side of the outer distal shaft (<NUM>) and having a lumen (<NUM>) communicating with the lumen (<NUM>) of the outer distal shaft (<NUM>),
a distal side of the inner shaft (<NUM>) is disposed in the lumen (<NUM>) of the outer distal shaft (<NUM>), a proximal side of the inner shaft (<NUM>) is disposed on an outer surface of the outer proximal shaft (<NUM>), and the inner shaft (<NUM>) forms a proximal opening portion (<NUM>) which opens on an outer surface side of the outer proximal shaft (<NUM>),
the inner shaft (<NUM>) has a first region (150A) and a second region (150B) disposed on a proximal side of the first region (150A), in a range from a proximal end (<NUM>) of the outer distal shaft (<NUM>) disposed on the outer surface of the outer proximal shaft (<NUM>) to the proximal opening portion (<NUM>),
the first region (150A) is fixed to the outer surface of the outer proximal shaft (<NUM>), and
the second region (150B) is not fixed to the outer surface of the outer proximal shaft (<NUM>),
characterized in that the outer diameter of the outer proximal shaft (<NUM>) is smaller than the outer diameter of the outer distal shaft (<NUM>).