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 biological lumen such as a blood vessel.

A general balloon catheter includes an inner tube shaft provided with a lumen forming a guide wire lumen, an outer tube shaft provided with a lumen (inflation lumen) for circulating a pressurizing medium, and a balloon fixed to the inner tube shaft and the outer tube shaft. In the balloon catheter configured in this way, the inner tube shaft is located coaxially with the outer tube shaft, in a state where a distal end of the inner tube shaft is inserted into the lumen of the outer tube shaft so as to protrude from a distal side of the outer tube shaft.

When an operator causes the balloon catheter to pass through the lesion area such as the stenosed site in a medical procedure using the balloon catheter, in some cases, the operator may perform a thrust operation on the balloon catheter from a proximal side. For example, if the above-described thrust operation is performed on the balloon catheter in a state where a distal end of the balloon catheter bumps against the stenosed site, the inner tube shaft receives a reaction force responded to the thrust operation. In this manner, the inner tube shaft cannot move in a state where the inner tube shaft is parallel to the outer tube shaft while keeping coaxial with the outer tube shaft. Consequently, the inner tube shaft may be warped in some cases. If the inner tube shaft is warped in the balloon catheter, there is a possibility that a balloon fixed to the inner tube shaft may buckle. In addition, since the inner tube shaft is warped, there is a possibility that the balloon catheter may have poor pushing ability (pushing performance).

For example, with regard to the problem as described above, PTL <NUM> below has proposed the balloon catheter as follows. An outer surface of the inner tube shaft and an inner surface of the outer tube shaft are fusion-bonded to each other at a position separated to the proximal side from the balloon. In addition, PTL <NUM> discloses a method of fusion-bonding the outer surface of the inner tube shaft and the inner surface of the outer tube shaft to each other by an ultrasound fusion-bonding method, in which ultrasound waves are emitted from an ultrasound oscillation horn being pressed against the outer surface of the outer tube shaft.

As described above, according to the balloon catheter disclosed in PTL <NUM>, the outer surface of the inner tube shaft and the inner surface of the outer tube shaft are partially fusion-bonded to each other. In this manner, even in a case of performing the thrust operation in a state where the distal end of the balloon catheter bumps against the stenosed site, the inner tube shaft can move in the state where the inner tube shaft is parallel to the outer tube shaft while keeping coaxial with the outer tube shaft.

In addition, according to a method of manufacturing the balloon catheter disclosed in PTL <NUM>, an ultrasound fusion-bonding method is adopted as a method of fusion-bonding the outer surface of the inner tube shaft and the inner surface of the outer tube shaft to each other. In this manner, when fusion bonding is carried out, portions other than a joint portion are prevented from being affected by heat.

According to the above manufacturing method, a worker who carries out manufacturing work adjusts an output of the ultrasound waves oscillating from the ultrasound oscillation horn. In this manner, the worker can prevent the portions other than the joint portion from being affected by the heat.

However, in a case where the inner tube shaft and the outer tube shaft are fusion-bonded to each other by means of ultrasound fusion bonding, the heat quantity of fusion bonding contributing to the fusion bonding between the inner tube shaft and the outer tube shaft depends on a force that brings the inner tube shaft and the outer tube shaft into contact with each other or frictional resistance acting between the inner tube shaft and the outer tube shaft. Therefore, the ultrasound fusion bonding between the inner tube shaft and the outer tube shaft varies depending on a contact state between the inner tube shaft and the outer tube shaft or each material of the inner tube shaft and the outer tube shaft.

Therefore, in a case of adopting the ultrasound fusion bonding method using the ultrasound oscillation horn, the worker needs to consider the material in view of the frictional resistance between the inner tube shaft and the outer tube shaft. In addition, when the worker joins the inner tube shaft and the outer tube shaft to each other, while the worker accurately adjusts the contact state between the respective shafts, the worker has to precisely control an output of the ultrasound waves oscillating from the ultrasound oscillation horn, and a force or a position for pressing the ultrasound oscillation horn against the outer surface of the outer tube shaft. Therefore, depending on a shape or a material of the inner tube shaft or the outer tube shaft, the ultrasound fusion bonding may be less useful in some cases.

The present invention has been made in order to solve the above-described problems, and an object thereof is to provide a balloon catheter which allows easier fusion bonding between an inner tube shaft and an outer tube shaft and in which the inner tube shaft can be prevented from being warped when the inner tube shaft passes through a stenosed site, and to provide a method of manufacturing such a balloon catheter. Solution to Problem.

According to the present invention, there is provided a balloon catheter according to independent claim <NUM> and a method for manufacturing a balloon catheter according to independent claim <NUM>. The dependent claims relate to advantageous embodiments.

In manufacturing the balloon catheter configured as described above, the heat generating light is applied from the outer surface side of the outer tube shaft. In this manner, the heat generating light is absorbed by the first layer of the inner tube shaft having the higher optical absorption property than the outer tube shaft and the second layer of the inner tube shaft. In this manner, the first layer of the inner tube shaft is melted, and the inner tube shaft and the outer tube shaft are fusion-bonded to each other. Then, when the inner tube shaft and the outer tube shaft are fusion-bonded, the outer surface of the outer tube shaft and the inner surface of the inner tube shaft are less likely to be thermally affected by heat generation of the first layer. Accordingly, sliding ability of a guide wire passing through the lumen of the inner tube shaft can be prevented from being degraded, or a leakage can be prevented from occurring in the lumen of the outer tube shaft.

According to the method of manufacturing the balloon catheter, when the outer tube shaft and the inner tube shaft are fusion-bonded to each other, the heat generating light is applied from the outer surface side of the outer tube shaft. The heat generating light is absorbed in the contact location between the inner surface of the outer tube shaft and the outer surface of the inner tube shaft. If the heat generating light is absorbed, the first layer of the inner tube shaft is melted, thereby fusion boding the inner tube shaft and the outer tube shaft to each other. Therefore, a worker who manufactures the balloon catheter carries out relatively easy work for applying the heat generating light toward the outer tube shaft and the inner tube shaft. In this manner, while the outer surface of the outer tube shaft and the inner surface of the inner tube shaft are prevented from being excessively affected by the heat generation, the inner tube shaft and the outer tube shaft can be fusion-bonded to each other.

Hereinafter, an illustrative example not falling under the scope of the claims as well as an embodiment according to the present invention will be described with reference to each drawing. Dimensional proportions in the drawings are exaggerated and different from actual proportions for convenience of description, in some cases.

As illustrated in <FIG>, a balloon catheter <NUM> according to an illustrative example not falling under the scope of the claims is a medical device that widens and treats a lesion area by inflating a balloon <NUM> located on a distal side of a shaft <NUM> in the lesion area such as a stenosed site formed in a biological lumen.

The balloon catheter <NUM> is configured to serve as a balloon catheter for PTCA treatment used in order to widen the stenosed site of a coronary artery. However, for example, the balloon catheter <NUM> can be configured to serve as a balloon catheter in order to treat the lesion area such as the stenosed site formed in a biological organ such other blood vessels, a bile duct, a trachea, an esophagus, the other digestive tract, a urethra, an aurinasal lumen, and other organs.

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

As illustrated in <FIG>, the balloon catheter <NUM> has an elongated shaft <NUM>, the balloon <NUM> located on the distal side of the shaft <NUM>, and a hub <NUM> located on a proximal side of the shaft <NUM>.

In the description of the illustrative example, a side on which the balloon <NUM> is located will be referred to as a distal side of the balloon catheter <NUM>, a side on which the hub <NUM> is located will be referred to as a proximal side of the balloon catheter <NUM>, and a stretching direction of the shaft <NUM> will be referred to as an axial direction.

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

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

As illustrated in <FIG> and <FIG>, the shaft <NUM> has a proximal opening portion (proximal opening portion of the inner tube shaft <NUM>) <NUM> which communicates with the guide wire lumen <NUM> of the inner tube shaft <NUM>. The proximal opening portion <NUM> is formed in the vicinity of a proximal portion <NUM> (proximal portion of a first layer <NUM> and a second layer <NUM> of the inner tube shaft <NUM>) of the inner tube shaft <NUM>.

As illustrated in <FIG>, the outer tube shaft <NUM> has a distal side shaft 110A and a proximal side shaft 110B connected to the proximal side of the distal side shaft 110A.

The distal side shaft 110A and the proximal side shaft 110B are integrally connected (fusion-bonded) to the inner tube shaft <NUM> in the vicinity of the proximal opening portion <NUM> of the shaft <NUM>.

A lumen (not illustrated) of the distal side shaft 110A and a lumen (not illustrated) of the proximal side shaft 110B has the lumen (inflation lumen) <NUM> which communicates with an inflatable space <NUM> of the balloon <NUM> in a state where the distal side shaft 110A and the proximal side shaft 110B are connected to each other.

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

The inner tube shaft <NUM> has the distal member <NUM> on the distal side. In this manner, the biological organ can be prevented from being damaged when a distal end of the balloon catheter <NUM> comes into contact with the biological lumen (such as an intravascular wall). For example, the distal member <NUM> can be formed of a flexible resin material. However, a material of the distal member <NUM> is not particularly limited as long as the distal member <NUM> can be fixed to the inner tube shaft <NUM>.

As illustrated in <FIG>, the guide wire lumen <NUM> communicates with the lumen <NUM> of the distal member <NUM> on the distal side of the inner tube shaft <NUM>. In addition, as illustrated in <FIG>, the guide wire lumen <NUM> communicates with the proximal opening portion <NUM> on the proximal side of the inner tube shaft <NUM>. The guide wire lumen <NUM> is formed on an inner surface side of the second layer <NUM> of the inner tube shaft <NUM> (to be described later).

As illustrated in <FIG>, the balloon <NUM> has a distal portion <NUM> fixed to a distal portion <NUM> of the inner tube shaft <NUM>, a proximal portion <NUM> fixed to a distal portion <NUM> of the outer tube shaft <NUM>, and an intermediate portion <NUM> which forms a largest outer diameter portion formed between the distal portion <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> and the intermediate portion <NUM>, and a proximal side tapered portion <NUM> formed between the proximal portion <NUM> and the intermediate portion <NUM>.

The balloon <NUM> forms the inflatable space <NUM> which communicates with the lumen <NUM> between the balloon <NUM> and an outer peripheral surface of the shaft <NUM>. The balloon <NUM> is inflated in a radial direction intersecting the axial direction, if a fluid flows into the inflatable space <NUM>.

As illustrated in <FIG>, the inner tube shaft <NUM> has a contrast marker <NUM> which indicates a substantially center position in the axial direction of the intermediate portion <NUM> of the balloon <NUM>. For example, the contrast marker <NUM> can be formed of metal such as platinum, gold, silver, iridium, titanium, and tungsten, or an alloy thereof. The contrast marker <NUM> may be located at a position indicating a boundary portion between the distal side tapered portion <NUM> and the intermediate portion <NUM> in the inner tube shaft <NUM>, and a position indicating a boundary portion between the proximal side tapered portion <NUM> and the intermediate portion <NUM> in the inner tube shaft <NUM>.

As illustrated in <FIG>, for example, the hub <NUM> has a port <NUM> which can be connected in a liquid-tight and airtight manner to a supply device (not illustrated) such as an indeflator for supplying a fluid (for example, a contrast agent or a physiological salt solution). For example, the port <NUM> of the hub <NUM> can be configured to include a known luer taper configured so that a tube is connectable thereto and separable therefrom.

Next, the outer tube shaft <NUM> and the inner tube shaft <NUM> will be described in detail.

As illustrated in <FIG>, the inner tube shaft <NUM> has the first layer <NUM> and the second layer <NUM> to be located on the inner surface side of the first layer <NUM>. Specifically, the inner tube shaft <NUM> has the first layer <NUM> and the second layer <NUM> located on the inner surface side of the first layer <NUM> and existing coaxially with the first layer <NUM>.

The coaxial described above means that the respective layers <NUM> and <NUM> are arranged so that an axis passing through the distal side of the first layer <NUM> and an axis passing through the distal side of the second layer <NUM> extend substantially parallel to each other. The term does not mean only a state where the axes of the respective layers <NUM> and <NUM> strictly overlap each other.

The first layer <NUM> of the inner tube shaft <NUM> is formed of a material having a higher optical absorption property than the outer tube shaft <NUM> and the second layer <NUM> of the inner tube shaft <NUM>. In addition, the second layer <NUM> of the inner tube shaft <NUM> is formed of a material having a melting point higher than that of the first layer <NUM> of the inner tube shaft <NUM>. A specific example of a configuration material of the outer tube shaft <NUM> and a configuration material of the inner tube shaft <NUM> will be described later.

As illustrated in <FIG>, <FIG>, while the outer tube shaft <NUM> is recessed toward the inner tube shaft <NUM> side (axial center side of the shaft <NUM>), the outer tube shaft <NUM> is fusion-bonded to the first layer <NUM> of the inner tube shaft <NUM>. <FIG> is an enlarged view of a portion surrounded by a broken line portion 3A in <FIG>, and <FIG> is a sectional view (sectional view perpendicular to the axial direction of the inner tube shaft <NUM>) along an arrow line 4A-4A illustrated in <FIG>.

As illustrated in <FIG>, the shaft <NUM> has a fusion-bonded portion <NUM> in a portion fusion-bonded in a state where the outer tube shaft <NUM> is recessed toward the inner tube shaft <NUM> side.

For example, the fusion-bonded portion <NUM> is separated to the proximal side as much as <NUM> to <NUM> in the axial direction from the proximal portion <NUM> of the balloon <NUM>.

An axial position or an axial length (range) for forming the fusion-bonded portion <NUM>, and the number of the fusion-bonded portions <NUM> formed in one shaft <NUM> are not particularly limited as long as the lumen <NUM> of the outer tube shaft <NUM> is not closed by the fusion-bonded portion <NUM>.

As illustrated in <FIG>, the thickness of the first layer <NUM> of the inner tube shaft <NUM> increases toward the fusion-bonded portion <NUM>, in a cross section perpendicular to the axial direction of the inner tube shaft <NUM>.

When the fusion-bonded portion <NUM> is formed by fusion-boding the outer tube shaft <NUM> and the inner tube shaft <NUM> to each other, the first layer <NUM> of the inner tube shaft <NUM> is fusion-bonded to the outer tube shaft <NUM> in a state of partially coming into contact with the outer tube shaft <NUM>. After fusion-bonded, the first layer <NUM> of the inner tube shaft <NUM> has a concave portion <NUM>, a thickness increasing portion <NUM>, and a thickness maintaining portion <NUM>.

The concave portion <NUM> is formed in the fusion-bonded portion <NUM> and a peripheral portion thereof. The concave portion <NUM> is formed as follows. In a state where the first layer <NUM> is in contact with (is pressed against) the outer tube shaft <NUM>, heat is applied to the first layer <NUM>. In this manner, a resin configuring the first layer <NUM> flows into a periphery thereof from a contact location 106a (refer to <FIG>) between the first layer <NUM> and the outer tube shaft <NUM>. Therefore, the concave portion <NUM> forms a thinnest portion in the first layer <NUM> after the fusion-bonded portion <NUM> is formed.

The thickness increasing portion <NUM> of the first layer <NUM> includes a resin configuring the first layer <NUM> which flows into a side in the circumferential direction of the first layer <NUM> as the concave portion <NUM> is formed. That is, the thickness increasing portion <NUM> of the first layer <NUM> is formed as follows. The resin of the portion having the concave portion <NUM> of the first layer <NUM> flows into the thickness increasing portion <NUM> of the first layer <NUM> so as to increase an original thickness (thickness indicated by t1 in the drawing) of the first layer <NUM>. Therefore, the thickness of the thickness increasing portion <NUM> gradually increases as the thickness increasing portion <NUM> is closer to the fusion-bonded portion <NUM> of the first layer <NUM> along the circumferential direction of the first layer <NUM>.

The thickness maintaining portion <NUM> of the first layer <NUM> is formed in a portion which is hardly affected by the heat applied to the first layer <NUM> of the inner tube shaft <NUM> when the fusion-bonded portion <NUM> is formed. That is, the thickness maintaining portion <NUM> is formed in a direction away from the fusion-bonded portion <NUM> from the thickness increasing portion <NUM> in the circumferential direction of the first layer <NUM>.

As illustrated in <FIG>, the outer tube shaft <NUM> has a concave portion <NUM> and a convex portion <NUM>.

The concave portion <NUM> of the outer tube shaft <NUM> is formed so that the outer surface of the outer tube shaft <NUM> is recessed toward the inner tube shaft <NUM> side. The convex portion <NUM> of the outer tube shaft <NUM> is formed so that the inner surface of the outer tube shaft <NUM> protrudes to the inner tube shaft <NUM> side. The concave portion <NUM> and the convex portion <NUM> of the outer tube shaft <NUM> are formed by applying the heat thereto in a state where the outer tube shaft <NUM> and the inner tube shaft <NUM> are brought into contact with each other when the fusion-bonded portion <NUM> is formed.

As illustrated in <FIG>, the first layer <NUM> of the inner tube shaft <NUM> forms an outermost layer of the inner tube shaft <NUM>. Therefore, the first layer <NUM> of the inner tube shaft <NUM> is interposed between the inner surface of the outer tube shaft <NUM> and the outer surface of the second layer <NUM> of the inner tube shaft <NUM>.

As illustrated in <FIG>, the second layer <NUM> of the inner tube shaft <NUM> is thinner than the first layer <NUM> of the inner tube shaft <NUM>, in a cross section perpendicular to the axial direction of the inner tube shaft <NUM>.

The thin inner tube shaft <NUM> described above means that the thickness of the second layer <NUM> before the fusion-bonded portion <NUM> is formed is thinner than the thickness of the first layer <NUM> before the fusion-bonded portion <NUM> is formed. The thickness of the first layer <NUM> before the fusion-bonded portion <NUM> is formed is substantially the same as the thickness of the thickness maintaining portion <NUM>.

The thickness (thickness of the thickness maintaining portion <NUM>) t1 of the first layer <NUM> of the inner tube shaft <NUM> can be formed to be <NUM> to <NUM>, for example. A thickness t2 of the second layer <NUM> of the inner tube shaft <NUM> can be formed to be <NUM> to <NUM>, for example.

The second layer <NUM> of the inner tube shaft <NUM> mainly contributes to a decrease in sliding resistance of the guide wire <NUM> inserted into the guide wire lumen <NUM>. Therefore, even if the thickness t2 of the second layer <NUM> is formed to be relatively thin, there is no disadvantage in performance of the balloon catheter <NUM>.

Next, a configuration material of the balloon catheter <NUM> will be described.

For example, the balloon <NUM> can be formed of polyamide resin, polyamide elastomer resin, or a blend thereof, in addition to thermoplastic elastomer such as vinyl chloride, polyurethane elastomer, polystyrene elastomer, styrene-ethylene-butylene-styrene copolymer (SEBS), and styrene-ethylene-propylene-styrene copolymer (SEPS), thermoplastic resins such as PET, thermosetting resins such as rubber and silicone elastomer. In addition, the balloon <NUM> may be a multilayer balloon having two or more layers. It is preferable that the balloon <NUM> is formed of the polyamide resin, polyamide elastomer resin, or a blend thereof. In this case, in the balloon <NUM>, in a case where the outer tube shaft <NUM> is formed of polyamide resin and the first layer <NUM> of the inner tube shaft <NUM> is formed of a polyamide layer, a fixing force (fusion bonding force) between the outer tube shaft <NUM> and the inner tube shaft <NUM> can be strengthened.

For example, the distal member <NUM> can be formed of polyolefin (for example, polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or a mixture of the above-described two or more materials), polymeric materials such as polyvinyl chloride, polyamide, polyamide elastomer, polyurethane, polyurethane elastomer, polyimide, fluorocarbon resin, or a mixture thereof, and alternatively, a multilayer tube having the above-described two or more polymeric materials. It is preferable that the distal member <NUM> is formed of a material softer than the materials forming the first layer <NUM> and the second layer <NUM> of the inner tube shaft <NUM>.

For example, the outer tube shaft <NUM> can be formed of a material containing the polyamide resin (polyamide-based resin). The polyamide resin is not particularly limited as long as the polyamide resin has an acid amide bond (-CO-NH-) in the main chain. The polyamide resin is usually manufactured through polymerization (homopolymerization) of lactam or amino acid having a ring structure, or through condensation polymerization of dicarboxylic acid and diamine under the presence of a suitable catalyst.

Monomers that can be polymerized alone include ε-caprolactam, undecane lactam, lauryllactam, aminocaproic acid, <NUM>-aminoheptanoic acid, <NUM>-aminoundecanoic acid, <NUM>-aminododecanoic acid, <NUM>-aminononanoic acid, and piperidone.

In addition, dicarboxylic acid in a case of condensation polymerization of dicarboxylic acid and diamine includes adipic acid, sebacic acid, dodecanedicarboxylic acid, glutaric acid, terephthalic acid, <NUM>-methylterephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Diamine includes tetramethylenediamine, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, paraphenylenediamine, and metaphenylenediamine.

A polyamide elastomer resin may be used as the polyamide resin. For example, the polyamide elastomer resin includes a block copolymer of polyamide (hard segment) and polyether (soft segment). More specifically, the polyamide elastomer resin includes a block copolymer of nylon <NUM> and polytetramethylene glycol or a block copolymer of nylon <NUM> and polytetramethylene glycol.

As the polyamide resin, it is preferable to use one having no segment other than polyamide. For example, nylon <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 6T, <NUM>/<NUM>, <NUM>/<NUM>, <NUM>/6T, and 6T/6I are used. Among the above-described materials, nylon <NUM> and nylon <NUM> (polyamide <NUM>) are more preferably used as the polyamide resin.

An end of the polyamide resin may be sealed with a carboxyl group or an amino group. The above-described polyamide resin can be used alone, or can be used in combination of two or more types.

Commercially available products may be used as the polyamide resin, examples of which include Daiamid (registered trademark) series (L1640, L1840, L1940, L1940W, L2140, L2140W, and L2121) and Vestamid (registered trademark) series (hitherto, Daicel-Evonik Ltd. ), Pebax (registered trademark) series (Arkema K. ), Amilan (registered trademark) series (Toray Industries, Inc. ), Leona (registered trademark) series (Asahi Kasei Corporation Ltd. ), UBEnylon (registered trademark) series (Ube Industries, Ltd. ), Reny (registered trademark) series (Mitsubishi Engineering-Plastics Corporation), Zytel (registered trademark) series (DuPont Corporation), Grilamid (registered trademark) and Grilflex (registered trademark) (hitherto, EMS-CHEMIE (Japan) Ltd. ), and Rilsamid (registered trademark) (Arkema K. In addition, the commercially available polyamide-based resin described above may be used alone, or a blend of two or more polyamide-based resins may be used.

The weight-average molecular weight of the polyamide-based resin is preferably <NUM>,<NUM> to <NUM>,<NUM>, and more preferably <NUM>,<NUM> to <NUM>,<NUM>. As the "weight-average molecular weight" of the polyamide-based resin, the present invention adopts a value measured by gel permeation chromatography (GPC).

The outer tube shaft <NUM> is not particularly limited as long as the optical absorption property is lower than the first layer <NUM> of the inner tube shaft <NUM>. However, for example, the outer tube shaft <NUM> can be formed to be transparent (including colored transparency). when the outer tube shaft <NUM> and the first layer <NUM> of the inner tube shaft <NUM> are fusion-bonded to each other, it is preferable that the outer tube shaft <NUM> is formed of a transparent (particularly, colorless and transparent) resin so that heat generating light can be efficiently applied to the first layer <NUM> of the inner tube shaft <NUM> after passing through the outer tube shaft <NUM>.

For example, the first layer <NUM> of the inner tube shaft <NUM> can be formed of a polyamide layer containing a pigment. With regard to the polyamide resin suitably which can be preferably used for the first layer <NUM> of the inner tube shaft <NUM> and a molecular weight thereof, those described as the configuration material of the outer tube shaft <NUM> can be applied thereto. From a viewpoint of fusion bonding performance, it is preferable that the same polyamide-based resin is used for the outer tube shaft <NUM> and the first layer <NUM> of the inner tube shaft <NUM>.

The pigment contained in the first layer <NUM> of the inner tube shaft <NUM> is obtained by adding various colors such as a black, red, green, blue, yellow, purple, or white color to the first layer <NUM>. The color of the first layer <NUM> colored by the pigment is not particularly limited as long as the first layer <NUM> has a higher optical absorption property than the outer tube shaft <NUM> and the second layer <NUM>. However, for example, from a viewpoint of improving the optical absorption property, it is preferable to use the black color.

Examples of the pigment may include inorganic pigments such as carbon black, titanium oxide, barium sulfate, iron oxide (black iron oxide, yellow iron oxide, and red iron oxide), chromium oxide, ultramarine blue (ultramarine blue and ultramarine violet color), nickel titanium yellow, Prussian blue, Milori blue, cobalt blue, Viridian, and molybdenum red. Examples of the pigment may also include organic pigments such as quinacridone (for example, quinaclide red), perylene (for example, perylene red), anthraquinone (for example, anthraquinone yellow), azo (for example, condensed azo yellow organic pigment), and phthalocyanine pigment (for example, halogenated phthalocyanine such as copper phthalocyanine and high chloride copper phthalocyanine). The above pigments can be used alone, or can be used in combination of two or more types.

In addition, the pigment may be contained in the first layer <NUM> of the inner tube shaft <NUM> in a form of a colorant containing a predetermined dispersant for dispersing the pigment into the resin.

For example, the second layer <NUM> of the inner tube shaft <NUM> can be formed of a fluorine resin such as PTEF, ETFE, and PFA. The second layer <NUM> of the inner tube shaft <NUM> may employ a fluorine resin alone, or may employ a combination of two or more fluorine resins. In addition, in a case where the first layer <NUM> of the inner tube shaft <NUM> is formed of the polyamide-based resin, the second layer <NUM> of the inner tube shaft <NUM> may be formed of an adhesive fluorine resin (a resin having low friction coefficient characteristics, which are inherent in fluorocarbon resin, and having an improved affinity for the polyamide resin, which is created by introducing functional groups into fluorocarbon resin). For example, the adhesive fluorine resin is homopolymer or copolymer having a tetrafluoroethylene unit, and includes the resin having functional groups such as a carbonate group, a carboxylic acid halide group, a hydroxyl group, a carboxyl group, and an epoxy group at a terminal or a side chain. For example, the commercially available product includes Neoflon EFEP (Daikin Industries, Ltd. ), Neoflon CPT (Daikin Industries, Ltd. ), and LM-ETFE AH2000 (Asahi Glass Co. In a case where the first layer <NUM> of the inner tube shaft <NUM> is formed of the polyamide-based resin, the second layer <NUM> of the inner tube shaft <NUM> may employ the adhesive fluorine resin alone, or may employ a combination of two or more adhesive fluorine resins.

The second layer <NUM> (resin as a main raw material for forming the second layer <NUM>) of the inner tube shaft <NUM> is preferably formed of a material whose melting point is at least <NUM> (degrees) higher than the first layer <NUM> (resin as a main raw material for forming the first layer <NUM>) of the inner tube shaft <NUM>, and is more preferably formed of a material whose melting point is at least <NUM> higher. As will be described later in examples, if a difference between the melting points is at least <NUM>, the second layer <NUM> can be preferably prevented from being melted when the fusion-bonded portion <NUM> is formed. The difference between the melting point of the second layer <NUM> of the inner tube shaft <NUM> and the melting point of the first layer <NUM> of the inner tube shaft <NUM> is preferably <NUM> or lower. In a case where the inner tube shaft <NUM> having the first layer <NUM> and the second layer <NUM> is molded by means of co-extrusion molding, if the difference between the melting point of the second layer <NUM> of the inner tube shaft <NUM> and the melting point of the first layer <NUM> of the inner tube shaft <NUM> is <NUM> or lower, the inner tube shaft <NUM> can be easily formed.

The second layer <NUM> of the inner tube shaft <NUM> is not particularly limited as long as the optical absorption property is lower than the first layer <NUM> of the inner tube shaft <NUM>. However, for example, the second layer <NUM> of the inner tube shaft <NUM> can be formed to be colorless and transparent.

In the inner tube shaft <NUM> including the first layer <NUM> and the second layer <NUM>, for example, a core bar is covered by a resin material for forming the second layer <NUM> of the inner tube shaft <NUM>. Thereafter, the core bar covered by the resin material for forming the second layer <NUM> is covered by the resin material for forming the first layer <NUM> of the inner tube shaft <NUM>. Thereafter, the molding can be performed by removing the core bar from the inner tube shaft <NUM> having the first layer <NUM> and the second layer <NUM>. Similarly, the inner tube shaft <NUM> including the first layer <NUM> and the second layer <NUM> can be formed as follows by means of the co-extrusion molding. For example, the resin material configuring the first layer <NUM> of the inner tube shaft <NUM> and fine powder or coating dispersion (further containing the pigment for the first layer <NUM>) of the resin material configuring the second layer <NUM> of the inner tube shaft <NUM> are prepared. A third layer <NUM> to be described later in an embodiment can also be formed as follows. The core bar is covered by the resin material for forming the second layer <NUM>. Thereafter, before the core bar is covered by the resin material for forming the first layer <NUM>, the core bar covered by the resin material for forming the second layer <NUM> is covered by the resin material for forming the third layer <NUM>. Similarly, the third layer <NUM> to be described later in the embodiment can also be formed together with the first layer <NUM> and the second layer <NUM> by means of the co-extrusion molding.

Next, a method of manufacturing the balloon catheter <NUM> according to the illustrative example not falling under the scope of the claims will be described.

First, a worker who manufactures the balloon catheter <NUM> supplies (prepares) the outer tube shaft <NUM>, the inner tube shaft <NUM>, and the balloon <NUM>.

As illustrated in <FIG>, the worker locates the inner tube shaft <NUM> so that the distal portion <NUM> of the inner tube shaft <NUM> protrudes from the distal end (distal opening portion) of the outer tube shaft <NUM>. The worker fixes (for example, fusion-bonds) the balloon <NUM> to the distal side of the inner tube shaft <NUM> and the distal side of the outer tube shaft <NUM>.

The outer tube shaft <NUM> (distal side shaft 110A and proximal side shaft 110B) and the inner tube shaft <NUM> may be prepared in a state where both the shafts <NUM> and <NUM> are fixed (fusion-bonded) to each other in the vicinity of the proximal opening portion <NUM> of the shaft <NUM> while the inner tube shaft <NUM> protrudes from the distal end of the outer tube shaft <NUM>. Alternatively, in a state where both the shafts <NUM> and <NUM> are not fixed to each other, both the shafts <NUM> and <NUM> may be prepared. Thereafter, both the shafts <NUM> and <NUM> are fixed to each other, and the worker may proceed to fixing work of the balloon <NUM>. In addition, it is preferable to fix the distal member <NUM> to the distal end of the inner tube shaft <NUM> as illustrated in <FIG> before the fixing work of the balloon <NUM> is carried out.

Next, as illustrated in <FIG>, in a state where a portion of the outer surface of the inner tube shaft <NUM> is brought into contact with the inner surface of the outer tube shaft <NUM>, the worker applies heat generating light L from the outer surface side of the outer tube shaft <NUM> to the contact location 106a (location including a boundary surface on which the outer surface of the inner tube shaft <NUM> comes into contact with the inner surface of the outer tube shaft <NUM>) between the inner tube shaft <NUM> and the outer tube shaft <NUM>. The outer surface of the inner tube shaft <NUM> and the inner surface of the outer tube shaft <NUM> can be brought into contact with each other as follows. For example, a predetermined jig (for example, the core bar <NUM> illustrated in <FIG>) located on the inner surface side of the inner tube shaft <NUM> is used. While the inner tube shaft <NUM> is pressed against the outer tube shaft <NUM> side, the outer tube shaft <NUM> is pressed against the inner tube shaft <NUM> side by using a predetermined jig located on the outer surface side of the outer tube shaft <NUM>.

The heat generating light L is not particularly limited as long as the first layer <NUM> of the inner tube shaft <NUM> can be melted. For example, it is possible to use a fiber laser (wavelength <NUM>,<NUM>), a YAG laser (wavelength <NUM>,<NUM>), or a laser diode (<NUM>, <NUM>, and <NUM>).

The heat generating light L applied from the outer surface side of the outer tube shaft <NUM> is transmitted through the outer tube shaft <NUM>, and is applied to the contact location 106a. The above-described transmission does not mean that the heat generating light L is not completely absorbed by the outer tube shaft <NUM>. For example, the heat generating light may be partially absorbed by the outer tube shaft <NUM> to such an extent that the outer tube shaft <NUM> is not excessively melted.

A portion of the first layer <NUM> (contact location 106a and the peripheral portion) of the inner tube shaft <NUM> absorbs the heat generating light L. Heat is generated so that the portion is melted. The melted portion of the first layer <NUM> forms the fusion-bonded portion <NUM> for fusion-bonding the inner tube shaft <NUM> and the outer tube shaft <NUM> to each other (refer to <FIG>).

As described above, the outer tube shaft <NUM> is formed of a material having a lower optical absorption property than the first layer <NUM> of the inner tube shaft <NUM>. Therefore, the outer tube shaft <NUM> has relatively low ability to absorb the heat generating light L applied from the outer surface side of the outer tube shaft <NUM>, and the outer tube shaft <NUM> is less likely to be melted by the heat generating light L. Similarly to the outer tube shaft <NUM>, the second layer <NUM> of the inner tube shaft <NUM> is formed of the material having the lower optical absorption property than the first layer <NUM> of the inner tube shaft <NUM>. Therefore, the second layer <NUM> of the inner tube shaft <NUM> has relatively low ability to absorb the heat generating light L, and the second layer <NUM> is less likely to be melted by the heat generating light L. Furthermore, the second layer <NUM> of the inner tube shaft <NUM> is formed of a material having a melting point higher than that of the first layer <NUM>. Accordingly, the second layer <NUM> can be preferably prevented from being melted by the heat generating light L or due to the influence of the heat generated in the first layer <NUM>.

As illustrated in <FIG>, if the fusion-bonded portion <NUM> is formed in the shaft <NUM>, the concave portion <NUM> is formed in the vicinity of the fusion-bonded portion <NUM> in the first layer <NUM> of the inner tube shaft <NUM>. The thickness increasing portion <NUM> whose thickness increases toward the concave portion <NUM> is formed within a prescribed certain range in the circumferential direction from the concave portion <NUM>. In addition, the thickness maintaining portion <NUM> in which the thickness of the first layer <NUM> is maintained regardless of the presence or absence of the fusion-bonded portion <NUM> is formed at a position separated as much as a prescribed distance in the circumferential direction from the concave portion <NUM> and the thickness increasing portion <NUM>.

After the fusion-bonded portion <NUM> is formed, the worker can manufacture the balloon catheter <NUM> by attaching the hub <NUM> or a strain relief portion, for example.

Next, an operation of the balloon catheter <NUM> and the method of manufacturing the balloon catheter <NUM> according to the illustrative example not falling under the scope of the claims will be described.

The balloon catheter <NUM> according to the illustrative example not falling under the scope of the claims includes the outer tube shaft <NUM> having the lumen <NUM>, the inner tube shaft <NUM> located in the lumen <NUM> of the outer tube shaft <NUM>, and the balloon <NUM> fixed to the distal side of the inner tube shaft <NUM> and the distal side of the outer tube shaft <NUM>. In addition, the inner tube shaft <NUM> has the first layer <NUM> and the second layer <NUM> located on the inner surface side of the first layer <NUM>. The outer tube shaft <NUM> is fusion-bonded to the first layer <NUM> and recessed toward the inner tube shaft <NUM> side. The first layer <NUM> is formed of the material having a higher optical absorption property than the outer tube shaft <NUM> and the second layer <NUM>. Then, the second layer <NUM> is formed of the material having a melting point higher than that of the first layer <NUM>.

In manufacturing the balloon catheter <NUM> configured as described above, the heat generating light is applied from the outer surface side of the outer tube shaft <NUM>. In this manner, the heat generating light is absorbed by the first layer <NUM> of the inner tube shaft <NUM> having the higher optical absorption property than the outer tube shaft <NUM> and the second layer <NUM> of the inner tube shaft <NUM>. In this manner, the first layer <NUM> of the inner tube shaft <NUM> is melted, and the inner tube shaft <NUM> and the outer tube shaft <NUM> are fusion-bonded to each other. Then, when the inner tube shaft <NUM> and the outer tube shaft <NUM> are fusion-bonded to each other, the outer surface of the outer tube shaft <NUM> and the inner surface (inner surface of the second layer <NUM>) of the inner tube shaft <NUM> are less likely to be thermally affected by heat generation of the first layer <NUM>. Accordingly, sliding ability of the guide wire <NUM> passing through the guide wire lumen <NUM> of the inner tube shaft <NUM> can be prevented from being degraded, or a leakage can be prevented from occurring in the lumen <NUM> of the outer tube shaft <NUM>.

In addition, the second layer <NUM> of the inner tube shaft <NUM> is thinner than the first layer <NUM> of the inner tube shaft <NUM>, in a cross section perpendicular to the axial direction of the inner tube shaft <NUM>. Therefore, the thickness of the second layer <NUM> of the inner tube shaft <NUM> can be prevented from increasing, and the diameter of the guide wire lumen <NUM> can be prevented from being narrowed.

In addition, the second layer <NUM> of the inner tube shaft <NUM> is formed of a material whose melting point is at least <NUM> higher than the first layer <NUM>. Therefore, the second layer <NUM> of the inner tube shaft <NUM> can more preferably prevent the second layer <NUM> from being melted due to the heat generating light or due to the influence of the heat generated in the first layer <NUM>.

In addition, the first layer <NUM> of the inner tube shaft <NUM> forms the outermost layer of the inner tube shaft <NUM>. Therefore, the worker who manufactures the balloon catheter <NUM> can cause the heat generating light applied from the outer surface side of the outer tube shaft <NUM> to more reliably reach the first layer <NUM>, and the first layer <NUM> of the inner tube shaft <NUM> can be easily melted.

In addition, the thickness of the first layer <NUM> of the inner tube shaft <NUM> increases toward the fusion-bonded portion <NUM> between the outer tube shaft <NUM> and the inner tube shaft <NUM>, in the cross section perpendicular to the axial direction of the inner tube shaft <NUM>. Therefore, when stress concentration occurs in the vicinity of the fusion-bonded portion <NUM>, the balloon catheter <NUM> can prevent the first layer <NUM> from starting to be broken in the vicinity of the fusion-bonded portion <NUM>.

The method of manufacturing the balloon catheter <NUM> according to the present illustrative example not falling under the scope of the claims supplies the outer tube shaft <NUM>, the inner tube shaft <NUM>, and the balloon <NUM> to be fixed to the distal side of the inner tube shaft <NUM> and the distal side of the outer tube shaft <NUM>. In addition, the inner tube shaft <NUM> has the first layer <NUM> and the second layer <NUM> located on the inner surface side of the first layer <NUM>. The first layer <NUM> is formed of the material having the high optical absorption property than the outer tube shaft <NUM> and the second layer <NUM>. The second layer <NUM> is formed of the material having a melting point higher than that of the first layer <NUM>. In addition, the inner tube shaft <NUM> is located so that the distal portion <NUM> of the inner tube shaft <NUM> protrudes from the distal end of the outer tube shaft <NUM>, and the balloon <NUM> is fixed to the distal side of the inner tube shaft <NUM> and the distal side of the outer tube shaft <NUM>. In addition, in a state where a portion of the outer surface of the inner tube shaft <NUM> is brought into contact with the inner surface of the outer tube shaft <NUM>, the heat generating light is applied from the outer surface side of the outer tube shaft <NUM> to the contact location 106a between the inner tube shaft <NUM> and the outer tube shaft <NUM>. A portion of the first layer <NUM> absorbs the heat generating light, and the heat is generated. In this manner, the first layer <NUM> is melted, thereby fusion-bonding the outer tube shaft <NUM> and the inner tube shaft <NUM> to each other.

According to the method of manufacturing the balloon catheter <NUM>, when the outer tube shaft <NUM> and the inner tube shaft <NUM> are fusion-bonded to each other, the heat generating light is applied from the outer surface side of the outer tube shaft <NUM>. The heat generating light is absorbed by the contact location 106a between the inner surface of the outer tube shaft <NUM> and the outer surface of the inner tube shaft <NUM>. If the first layer <NUM> of the inner tube shaft <NUM> absorbs the heat generating light, the inner tube shaft <NUM> and the outer tube shaft <NUM> are melted and fusion-bonded to each other. Therefore, the worker who manufactures the balloon catheter <NUM> carries out relatively simple work for applying the heat generating light toward the outer tube shaft <NUM> and the inner tube shaft <NUM>. In this manner, while the outer surface of the outer tube shaft <NUM> and the inner surface of the inner tube shaft <NUM> are prevented from being excessively affected by the heat generation, the inner tube shaft <NUM> and the outer tube shaft <NUM> can be fusion-bonded to each other.

Next, an embodiment according to the above-described embodiment will be described. Elements the same as those according to the above-described embodiment are applicable to members or manufacturing processes which are not particularly described in the embodiment, and thus, description thereof will be omitted.

<FIG> is a view illustrating a shaft <NUM> of the balloon catheter according to the embodiment. <FIG> is an axially orthogonal sectional view (sectional view corresponding to <FIG>) of the shaft <NUM>.

The shaft <NUM> according to the embodiment is different from the above-described illustrative example in that the inner tube shaft <NUM> has a different configuration.

Specifically, the inner tube shaft <NUM> has a third layer <NUM> between the first layer <NUM> and the second layer <NUM>. The third layer <NUM> is formed of a material having a higher affinity for the second layer <NUM> than the first layer <NUM>. The third layer <NUM> is preferably formed of a material having a higher affinity for the second layer <NUM> than the first layer <NUM> and having an affinity for the first layer <NUM> equal to or higher than that of the second layer <NUM>.

For example, the first layer <NUM> and the second layer <NUM> can be formed of any of the materials as listed above in the embodiment.

For example, the third layer <NUM> can be formed of the polyamide resin listed as an example of the material of the first layer <NUM>, other polyamide resins, or a polyamide elastomer resin (for example, Pebax which is the polyamide elastomer resin). A configuration material of the third layer <NUM> has a lower content of the pigment than the first layer <NUM>.

For example, the third layer <NUM> may be colored with a predetermined color pigment, similarly to the first layer <NUM>. The third layer <NUM> is formed of a material having the lower optical absorption property than the first layer <NUM>. In a case where the third layer <NUM> is formed in this way, the third layer <NUM> can prevent the heat from being transferred to the second layer <NUM>, and can preferably prevent the inner surface of the second layer <NUM> from being melted when the fusion-bonded portion <NUM> is formed.

For example, a thickness t3 of the third layer <NUM> can be thicker than the thickness t1 of the first layer <NUM> and the thickness t2 of the second layer <NUM>. In a case where the third layer <NUM> is disposed therein, for example, the thickness (thickness of the thickness maintaining portion <NUM>) t1 of the first layer <NUM> of the inner tube shaft <NUM> can be formed to be <NUM> to <NUM>. For example, the thickness t2 of the second layer <NUM> of the inner tube shaft <NUM> can be formed to be <NUM> to <NUM>. For example, the thickness t3 of the third layer <NUM> can be formed to be thicker than the thickness t1 of the first layer <NUM> and the thickness t2 of the second layer <NUM>.

As described above, the inner tube shaft <NUM> according to the embodiment has the third layer <NUM> between the first layer <NUM> and the second layer <NUM>. The third layer <NUM> has a higher affinity for the second layer <NUM> than the first layer <NUM>. Therefore, it is possible to advantageously prevent separation (delamination) between the second layer <NUM> and the third layer <NUM>.

Next, advantageous effects according to the present invention will be described with reference to the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, operations are performed at room temperature (<NUM>).

In these examples (not falling under the scope of the claims), the outer tube shaft and the inner tube shaft having the first layer and the second layer were prepared. The heat generating light was applied so as to form the fusion-bonded portion described in the embodiment. As the heat generating light, a laser beam emitted by a YAG laser oscillator was used. After the fusion-bonded portion was formed, it was checked whether or not the second layer had deformation (melting), which would cause leakage or a decrease in sliding ability of the guide wire.

The following outer tube shaft and inner tube shaft were prepared for examples (not falling under the scope of the claims) and comparative examples.

Shafts of Comparative Example <NUM> were prepared as in Example <NUM>, except that the polyamide layer forming the first layer of the inner tube shaft contained no pigment. That is, in Comparative Example <NUM>, no pigment is not contained in each of the first layer and the second layer.

Shafts of Comparative Example <NUM> were prepared as in Example <NUM>, except that the polyamide layer forming the first layer of the inner tube shaft contained no pigment. That is, in Comparative Example <NUM>, no pigment is contained in each of the first layer and the second layer.

As shown in Table <NUM>, it was found that the first and second layers were satisfactorily fusion-bonded to each other in Examples <NUM>, <NUM>, and <NUM>. It was also found that in Examples <NUM>, <NUM>, and <NUM>, the second layer did not undergo deformation (melting), which would cause leakage or a decrease in the sliding ability of the guide wire, because of the melting point of the second layer higher (at least <NUM>) than the that of the first layer.

In Comparative Example <NUM>, the second layer underwent deformation (melting), which would cause leakage or a decrease in the sliding ability of the guide wire. This may be because the melting point of the second layer is lower than that of the first layer.

The formation of a fusion-bonded portion was not observed in Comparative Examples <NUM>, <NUM>, <NUM>, and <NUM>. This may be because both the first and second layers containing no pigment allow part of the inner tube shaft to absorb the laser beam so that no heat is generated in part of the inner tube shaft.

The results indicate that when the first layer of the inner tube shaft is formed of a material having a higher optical absorption property than that of the outer tube shaft and the second layer of the inner tube shaft and when the second layer of the inner tube shaft is formed of a material having a melting point higher than that of the first layer of the inner tube shaft, the inner tube shaft and the outer tube shaft can be fusion-bonded to each other using a laser beam and the second layer can be prevented from undergoing deformation (melting), which would cause leakage or a decrease in the sliding ability of the guide wire.

In the examples, an outer tube shaft and an inner tube shaft having three layers: first, second, and third layers were prepared, and heat generating light was applied so that a fusion-bonded portion was formed as described in the embodiment. Unless otherwise specified, the conditions are the same as those for the example of the inner tube shaft having the two layers: the first and second layers.

Shafts of Example <NUM> were prepared as in Example <NUM>, except that the second layer was made of a fluorine resin (ETFE). The melting point of the material of the second layer is approximately <NUM> to <NUM>.

Shafts of Example <NUM> were prepared as in Example <NUM>, except that the third layer was made of Pebax <NUM> (Arkema K. The third layer of the inner tube shaft was colorless and transparent. In addition, the melting point of the material of the third layer is approximately <NUM> to <NUM>. In addition, the material of the third layer contains no pigment.

Shafts of Example <NUM> were prepared as in Example <NUM>, except that carbon black (pigment) was contained in the third layer. That is, in Example <NUM>, the pigment is contained in the first and third layers.

Shafts of Comparative Example <NUM> were prepared as in Example <NUM>, except that the first layer contained no pigment. That is, in Comparative Example <NUM>, no pigment is contained in each of the first, second, and third layers.

Shafts of Comparative Example <NUM> were prepared as in Example <NUM>, except that no pigment was contained in the first layer. That is, in Comparative Example <NUM>, no pigment is contained in each of the first, second, and third layers.

Shafts of Comparative Example <NUM> were prepared as in Comparative Example <NUM>, except that no pigment was contained in the second layer. That is, in Comparative Example <NUM>, the pigment is contained in the first layer, and no pigment is contained in the second and third layers.

Shafts of Comparative Example <NUM> were prepared as in Comparative Example <NUM>, except that no pigment was contained in the first layer. That is, in Comparative Example <NUM>, the pigment is contained in the third layer, and no pigment is contained in the first and second layers.

Shafts of Comparative Example <NUM> were prepared as in Comparative Example <NUM>, except that no pigment was contained in the first and second layers. That is, in Comparative Example <NUM>, no pigment was contained in each of the first, second, and third layers.

Shafts of Comparative Example <NUM> were prepared as in Comparative Example <NUM>, except that no pigment was contained in the first layer. That is, in Comparative Example <NUM>, no pigment is contained in each of the first, second, and third layers.

As shown in Table <NUM>, it was found that the first, second, and third layers were satisfactorily fusion-bonded together in Examples <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. In addition, it was also found that in Examples <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, the second layer did not undergo deformation (melting), which would cause leakage or a decrease in the sliding ability of the guide wire, because of the melting point of the second layer higher (at least <NUM> higher) than that of the first layer.

Furthermore, it has been demonstrated that in Examples <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, the third layer can function as a buffer layer for reducing the heat transfer between the first and second layers, so that the second layer can be more advantageously prevented from being deformed. In addition, in Examples <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, heat generating light is less absorbed into the third layer, which contains no pigment. Therefore, it has been demonstrated that in Examples <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>, the second layer can be more advantageously prevented from being deformed than in Examples <NUM> and <NUM>.

In Comparative Examples <NUM> and <NUM>, no fusion-bonded portion was formed because of no pigment in each of the first, second, and third layers.

In Comparative Examples <NUM> and <NUM>, the second layer underwent deformation (melting), which would cause leakage or a decrease in the sliding ability of the guide wire. This may be because the melting point of the second and third layers is lower than that of the first layer. In addition, it was observed that in Comparative Example <NUM>, the second layer, which contained the pigment, more significantly underwent deformation (melting).

In Comparative Example <NUM>, the second layer underwent deformation (melting), which would cause leakage or a decrease in the sliding ability of the guide wire, because the third layer between the first and second layers contained the pigment. In Comparative Example <NUM>, the melting point of the second layer forming the inner peripheral surface of the inner tube shaft is lower than that of the first layer and is approximately equal to that of the third layer. Therefore, it is suggested that in Comparative Example <NUM>, heat may be transferred from the third layer to the second layer to deform the second layer when heat generating light is applied so that a fusion-bonded portion can be formed.

In Comparative Example <NUM>, no fusion-bonded portion was formed because of no pigment in each of the first, second, and third layers.

The results indicate that when the third layer is provided between the first and second layers of the inner tube shaft, the second layer can be more effectively prevented from undergoing deformation (melting), which would cause leakage or a decrease in the sliding ability of the guide wire.

While the balloon catheter and the method of manufacturing the balloon catheter according to the present invention have been described with reference to the embodiment, the scope of the present invention is not limited to the contents described in the embodiment, and may be appropriately modified based on the scope of the appended claims.

Claim 1:
A balloon catheter (<NUM>) comprising:
an outer tube shaft (<NUM>) having a lumen (<NUM>);
an inner tube shaft (<NUM>) located in the lumen (<NUM>) of the outer tube shaft (<NUM>); and
a balloon (<NUM>) fixed to a distal side of the inner tube shaft (<NUM>) and a distal side of the outer tube shaft (<NUM>),
characterized in that
the inner tube shaft (<NUM>) has a first layer (<NUM>) and a second layer (<NUM>) located on an inner surface side of the first layer (<NUM>),
the outer tube shaft (<NUM>) is fusion-bonded to the first layer (<NUM>) and recessed toward the inner tube shaft side, wherein the outer tube shaft (<NUM>) and the inner tube shaft (<NUM>) have a fusion-bonded portion (<NUM>) in a portion fusion-bonded in a state where the outer tube shaft (<NUM>) is recessed toward the inner tube shaft side,
the first layer (<NUM>) is formed of a material having a higher optical absorption property than the outer tube shaft (<NUM>) and the second layer (<NUM>), and
the second layer (<NUM>) is formed of a material having a melting point higher than that of the first layer (<NUM>),
wherein the inner tube shaft (<NUM>) has a third layer (<NUM>) between the first layer (<NUM>) and the second layer (<NUM>), and
the third layer (<NUM>) has a higher affinity for the second layer (<NUM>) than the first layer (<NUM>),
wherein the third layer (<NUM>) is formed of a material having a lower optical absorption property than the first layer (<NUM>).