Patent Description:
In recent years, for a reason that surgical invasiveness is fairly low, a treatment in a lumen such as a blood vessel using a catheter has been actively performed. For example, in general, the catheter used by being selectively introduced into a complexly branched blood vessel in a body is selectively pushed in along a guide wire introduced in advance into the blood vessel to circulate a therapeutic drug, a diagnostic contrast agent, or the like from a proximal side to a distal side.

An radiopaque marker is disposed in a shaft such that a position of the catheter in the lumen can be recognized from the outside of the body. For example, PTL <NUM> describes a catheter in which a marker is fixed to an outer peripheral surface of a shaft by punching. PTL <NUM> describes a catheter in which a marker is disposed on an inner peripheral surface of a shaft and from which a portion protruding in a radial direction on an outer surface of the shaft is removed such that the catheter is flat.

The shaft is formed thin such that the shaft can be inserted into the blood vessel or the like. Alternatively, in order to ensure pushing performance (pushability), torque transmission performance, or the like, a reinforcement body may be provided in which a wire is braided. Meanwhile, for example, when the shaft is inserted from a radial artery of a hand and treatment of a lower limb is performed, a long shaft is required. When the shaft is long, it is difficult to transmit a pushing force and a torque that are applied to a proximal portion of the shaft to a distal portion of the shaft. Therefore, in order to improve the pushing performance and the torque transmission performance, for example, it is conceivable to increase a wire diameter of the wire of the reinforcement body.

When the wire diameter of the braided wire is increased, a thickness of the shaft of the portion where the marker is provided is also increased when the marker is disposed in the shaft where the reinforcement body is embedded.

The invention has been made to solve the above-described problems, and an object of the invention is to provide a catheter capable of preventing an increase in a thickness of a shaft while disposing an radiopaque marker on the shaft provided with a reinforcement body.

This problem is solved by a catheter according to independent claim <NUM>. The dependent claims relate to advantageous embodiments.

In the catheter configured as described above, the outer diameter of the shaft provided with the reinforcement body and the radiopaque marker is not too large, and/or the inner diameter of the shaft is not too small. Therefore, it is possible to prevent an increase in the thickness of the shaft while disposing the marker on the shaft provided with the reinforcement body.

A thickness of an outer layer of the shaft in the portion where the marker is disposed may be the same as a thickness of an outer layer of the shaft in the portion adjacent to the marker in the axial direction of the shaft. Accordingly, it is possible to prevent an increase in the thickness of the shaft while making the thickness of the outer layer uniform regardless of the presence or absence of the marker.

The marker may include at least one convex portion on at least an inner surface side. Accordingly, the marker is firmly fixed to the shaft. Therefore, detachment of the marker from the shaft can be prevented.

An effective length of the shaft may be <NUM> or more. Accordingly, the catheter can easily reach an artery of a lower limb from an artery of an arm.

Hereinafter, the invention will be described with reference to the drawings. For convenience of explanation, dimensions in the drawings may be exaggerated and may be different from actual dimensions. In the specification and the drawings, components having substantially the same functional configuration are designated by the same reference signs, and a duplicate description thereof will be omitted. In the present specification, a side where a catheter is inserted into a biological lumen is referred to as a "distal side", and a side to be operated is referred to as a "proximal side".

A catheter <NUM> is introduced into a blood vessel from a radial artery of an arm, inserted into an artery of a lower limb, and used for treatment, diagnosis, and the like. The artery of the lower limb is an artery near and more peripheral to an aortoiliac bifurcated portion. As shown in <FIG>, a catheter <NUM> includes a long shaft <NUM>, a hub <NUM> coupled to a proximal end of the shaft <NUM>, and an strain relief <NUM> provided at a connection portion between the shaft <NUM> and the hub <NUM>.

As shown in <FIG>, the shaft <NUM> is a flexible tubular member, and a lumen <NUM> is formed inside from the proximal end to a distal end. A guide wire is inserted into the lumen <NUM> when the catheter <NUM> is inserted into a blood vessel. The lumen <NUM> can also be used as a passage for a drug solution, an embolic substance, a contrast agent, a medical instrument, or the like.

An effective length of the shaft <NUM> is not particularly limited, but is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, still more preferably <NUM> to <NUM>, and is <NUM>. Accordingly, the catheter <NUM> can reach the artery of the lower limb from the artery of the arm. The effective length of the shaft <NUM> is a length of a portion that can be inserted into a blood vessel, a sheath, or the like. The effective length is a length from a distal-most end of the strain relief <NUM> to a distal-most end of the shaft <NUM>. The effective length of the shaft <NUM> is preferably <NUM> or more when the catheter is introduced from a femoral artery, and is preferably <NUM> or more when the catheter approaches from a distal portion of a dorsalis pedis artery or a posterior tibial artery.

The shaft <NUM> is comprised by a plurality of layers, and includes an inner layer <NUM> forming an inner surface <NUM> of the lumen <NUM>, a reinforcement body <NUM> formed on an outer side of the inner layer <NUM>, a marker <NUM> disposed on an outer side of the reinforcement body <NUM> in a radial direction, and an outer layer <NUM> formed on an outer side of the inner layer <NUM> and the reinforcement body <NUM>. A thickness of the shaft <NUM> is larger than a sum of a thickness of the reinforcement body <NUM> and a thickness of the marker <NUM>. Therefore, the reinforcement body <NUM> and the marker <NUM> can be completely embedded inside the shaft <NUM>.

An inner diameter of the inner layer <NUM> is not particularly limited, but is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, still more preferably <NUM> to <NUM>, and is <NUM> in the present embodiment. The inner diameter of the inner layer <NUM> may be smaller than a portion adjacent in an axial direction X of the shaft <NUM> at a position covered by the marker <NUM>.

The lumen <NUM> is formed inside the inner layer <NUM>. As a constituent material of the inner layer <NUM>, a thermoplastic resin, a thermosetting resin, or the like can be used, and a fluorine-based resin such as polytetrafluoroethylene (PTFE), a low-friction material such as high-density polyethylene (HDPE), or the like is preferable.

The reinforcement body <NUM> is formed by braiding a plurality of wires <NUM> in a tubular shape with a gap around an outer periphery of the inner layer <NUM>. In the reinforcement body <NUM>, a small diameter portion <NUM> having a locally small outer diameter is formed in order to dispose the marker <NUM>. A length of the small diameter portion <NUM> in the axial direction X is preferably larger than or equal to a length of the marker <NUM> in the axial direction X such that the marker <NUM> can be accommodated. The reinforcement body <NUM> may be formed by winding the wires <NUM> in horizontal winding in the same direction, or winding the wires <NUM> while changing a winding direction, such as right-handed winding and left-handed winding. A winding pitch, an interstitial distance, an inclination angle with respect to a peripheral direction, and the like may be changed depending on a position. The configuration is not particularly limited. The small diameter portion <NUM> may not be formed.

A difference (D5-D6) between a maximum outer diameter D5 of the marker <NUM> and a maximum outer diameter D6 of the reinforcement body <NUM> in the portion adjacent to the marker <NUM> in the axial direction X of the shaft <NUM> is smaller than twice a thickness T of the marker <NUM>.

A wire diameter (diameter) of the wire <NUM> of the reinforcement body <NUM> is not particularly limited, but is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, still more preferably <NUM> to <NUM>, and is <NUM> in the present embodiment.

As the wire <NUM> used for the reinforcement body <NUM>, a metal wire made of metal such as stainless steel, platinum (Pt) and tungsten (W), resin fiber, carbon fiber, glass fiber, or the like can be used, or the plurality of these wires <NUM> may be used in combination.

The marker <NUM> is an radiopaque (X-ray contrast) tube body that enters the small diameter portion <NUM> from the outer side in the radial direction. When the marker <NUM> is disposed, after the reinforcement body <NUM> is disposed around the outer periphery of the inner layer <NUM>, a tube body formed of a material containing an radiopaque substance is disposed in a manner of surrounding the inner layer <NUM> and the reinforcement body <NUM>. Thereafter, the tube body is crimped from the outer side in the radial direction to form a plurality of concave portions <NUM> and a plurality of convex portions <NUM> on an inner peripheral surface of the tube body, and the tube body is reduced in diameter to dispose the marker <NUM> in the shaft <NUM>. Therefore, a cross-sectional shape of the marker <NUM> in a cross section orthogonal to the axial direction X of the shaft <NUM> is non-circular. In the present embodiment, the concave portion <NUM> extends in the axial direction X of the shaft <NUM> and is formed in a groove shape. The convex portion <NUM> extends in the axial direction X of the shaft <NUM> and is formed in a beam shape. The concave portion <NUM> and the convex portion <NUM> are arranged substantially uniformly in the peripheral direction of the marker <NUM>. The number of the concave portions <NUM> and the number of the convex portions <NUM> are not particularly limited, but a cross-sectional shape of the marker <NUM> approaches a circular shape as the number increases. The concave portion <NUM> may not be in the groove shape. The convex portion <NUM> may not be in the beam shape. For example, in the embodiment according to the invention shown in <FIG>, the concave portions <NUM> and the convex portions <NUM> are randomly formed.

As shown in <FIG> and <FIG> of <FIG>, the thickness T of the marker <NUM> can be an average value of the thicknesses T of the marker <NUM> in the cross section orthogonal to an axis of the shaft <NUM> at a predetermined position (for example, a center or an end portion in the axial direction X). The average value of the thicknesses T of the marker <NUM> in the cross section orthogonal to the axis of the shaft <NUM> may be, for example, a value obtained by dividing a cross-sectional area of the marker <NUM> in the cross section by a length (for example, an average value of a peripheral length of the inner peripheral surface of the marker <NUM> and a peripheral length of the outer peripheral surface of the marker <NUM>) of the marker <NUM> in the peripheral direction.

The thickness T of the marker <NUM> is not particularly limited, but is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, still more preferably <NUM> to <NUM>, and is <NUM> in the present embodiment.

As a constituent material of the marker <NUM>, a material kneaded with an X-ray contrast agent such as platinum, gold, silver, tungsten, iridium, or metal powders of an alloy thereof, or barium sulfate, bismuth oxide, or a coupling compound thereof can be suitably used.

As shown in <FIG>, the outer layer <NUM> is a tubular member that covers the outer periphery of the inner layer <NUM>, the reinforcement body <NUM>, and the marker <NUM>. The outer layer <NUM> forms an outer surface <NUM> that is a surface on the outer side of the shaft <NUM> in the radial direction. The outer surface <NUM> includes an outer layer convex portion <NUM> formed at a position where the marker <NUM> is covered. An outer diameter D1 of the outer layer convex portion <NUM> is larger than an outer diameter D2 of the portion adjacent to the outer layer convex portion <NUM> in the axial direction X of the shaft <NUM>. An outer diameter difference (D1-D2), which is a difference between the outer diameter D1 of the outer layer convex portion <NUM> and the outer diameter D2 of the portion (adjacent portion <NUM>) adjacent to the outer layer convex portion <NUM> in the axial direction X, is smaller than twice the thickness T of the marker <NUM>.

The outer diameter D1 of the outer layer convex portion <NUM> is not particularly limited, but is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, still more preferably <NUM> to <NUM>, and is <NUM> in the present embodiment.

The outer diameter D2 of the portion adjacent to the outer layer convex portion <NUM> is not particularly limited, but is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, still more preferably <NUM> to <NUM>, and is <NUM> in the present embodiment. The outer diameter difference (D1-D2), which is the difference between the outer diameter D1 and the outer diameter D2, is preferably <NUM> to <NUM>, more preferably <NUM> to <NUM>, still more preferably <NUM> to <NUM>, and is <NUM> in the present embodiment.

As a constituent material of the outer layer <NUM>, for example, a thermoplastic resin such as a polymer material such as polyolefin (for example, polyethylene, polypropylene, polybutene, an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer, an ionomer, or a mixture of two or more thereof), polyvinyl chloride, polyamide, a polyester elastomer, a polyamide elastomer, polyurethane, a polyurethane elastomer, polyimide, or fluororesin, or a mixture thereof, and a thermosetting resin such as epoxy resin can be used. The radiopaque substance may be mixed in the outer layer <NUM>.

The proximal portion of the shaft <NUM> is liquid-tightly fixed to the hub <NUM> by an adhesive, heat-welding, a fastener (not shown) or the like. The hub <NUM> functions as an insertion port of a guide wire or a medical instrument into the lumen <NUM>, an injection port of a drug solution, an embolic substance, a contrast agent, or the like into the lumen <NUM>, or the like, and also functions as a grip portion when the catheter <NUM> is operated. A constituent material of the hub <NUM> is not particularly limited, and for example, a thermoplastic resin such as polycarbonate, polyamide, polysulfone, polyarylate, or a methacrylate-butylene-styrene copolymer can be suitably used.

The strain relief <NUM> is made of an elastic material that surrounds the periphery of the shaft <NUM>, and prevents kinking of the shaft <NUM> at the connection portion between the shaft <NUM> and the hub <NUM>. As a constituent material of the strain relief <NUM>, for example, natural rubber, silicone resin, or the like can be suitably used.

Next, a method (not claimed) for manufacturing the catheter <NUM> according to the present embodiment will be described.

First, a long core wire having an outer diameter equal to the inner diameter of the inner layer <NUM> is prepared. Next, the inner layer <NUM> is formed on the core wire. The inner layer <NUM> may not be formed by extrusion molding, or may be formed by dip molding. Alternatively, the core wire may be inserted into the inner layer <NUM>, which is the tube body.

Thereafter, the reinforcement body <NUM> is formed in a manner of covering at least a part of the inner layer <NUM>. The reinforcement body <NUM> is formed by continuously winding the plurality of wires <NUM> on the inner layer <NUM> using a braid machine (braider).

Next, the marker <NUM> is disposed on the outer side of the inner layer <NUM> and the reinforcement body <NUM>, and the marker <NUM> is crimped by a crimping machine to bite into the reinforcement body <NUM>. Accordingly, the reinforcement body <NUM> receives a force from the outer side in the radial direction and is reduced in diameter, and the small diameter portion <NUM> is formed. The small diameter portion <NUM> may not be formed in the marker <NUM>. Thereafter, the outer layer <NUM> including the outer layer convex portion <NUM> is formed on the outer side of the inner layer <NUM>, the reinforcement body <NUM>, and the marker <NUM>. Accordingly, the outer diameter difference (D1-D2), which is the difference between the outer diameter D1 of the shaft <NUM> in the portion where the marker <NUM> is disposed and the outer diameter D2 of the shaft <NUM> in the portion adjacent to the marker <NUM> in the axial direction X of the shaft <NUM>, is smaller than twice the thickness T of the marker <NUM>. In the present embodiment, the portion adjacent to the marker <NUM> in the axial direction X is a portion on the distal side and/or the proximal side of the marker <NUM>. An inner diameter difference (D3-D4), which is a difference between an inner diameter D3 of the shaft <NUM> in the portion adjacent to the marker <NUM> in the axial direction X of the shaft <NUM> and an inner diameter D4 of the shaft <NUM> in the portion where the marker <NUM> is disposed, is smaller than twice the thickness T of the marker <NUM>. The inner diameter D3 and the inner diameter D4 may be equal or may not be equal to each other. A method for forming the outer layer <NUM> is not particularly limited. For example, the outer layer <NUM> may be formed by the extrusion molding, or may be formed by the dip molding. Alternatively, the outer layer <NUM> may be formed by disposing the tube body as a material of the outer layer <NUM> on the outer side of the inner layer <NUM>, the reinforcement body <NUM>, and the marker <NUM>, and then heating the tube body by covering the tube body with a heat-shrinkable tube. The tube body is softened or melted by heating, and is closely bonded to the outer side of the inner layer <NUM>, the reinforcement body <NUM>, and the marker <NUM> by a contraction force of the heat-shrinkable tube. Thereafter, the heat-shrinkable tube subjected to heat shrinkage is removed.

After the outer layer <NUM> is formed, the core wire is pulled out from the lumen <NUM> of the inner layer <NUM>. Thereafter, the hub <NUM> and the strain relief <NUM> are attached to the shaft <NUM>, and other members (for example, distal chips) are attached as necessary to complete the catheter <NUM>.

As described above, the catheter <NUM> according to the present embodiment is the catheter <NUM> that includes the shaft <NUM> including the lumen <NUM> communicating from the distal end to the proximal end. The shaft <NUM> includes the reinforcement body <NUM> including the plurality of wires <NUM> that are disposed in at least a part between the inner surface <NUM> of the shaft <NUM> forming the lumen <NUM> and the outer surface <NUM> of the shaft <NUM> and that are braided in the tubular shape, and at least one or more radiopaque markers <NUM> that are disposed between the reinforcement body <NUM> and the outer surface <NUM>. The outer diameter difference (D1-D2), which is the difference between the outer diameter D1 of the shaft <NUM> in the portion where the marker <NUM> is disposed and the outer diameter D2 of the shaft <NUM> in the portion adjacent to the marker <NUM> in the axial direction X of the shaft <NUM>, is smaller than twice the thickness T of the marker <NUM>. Accordingly, the outer diameter of the shaft <NUM> provided with the reinforcement body <NUM> and the radiopaque marker <NUM> is not too large. Therefore, it is possible to prevent an increase in the thickness of the shaft <NUM> while disposing the marker <NUM> in the shaft <NUM> provided with the reinforcement body <NUM>. By preventing the increase in the thickness of the shaft <NUM>, the inner diameter of the shaft <NUM> can be made as large as possible while the outer diameter of the shaft <NUM> can be made as small as possible. Such a catheter <NUM> is particularly effective when a blood vessel (for example, the radial artery) to be introduced is thin and a blood vessel (for example, the artery of the lower limb) to be treated or diagnosed is thick.

The difference (D5-D6) between the maximum outer diameter D5 of the marker <NUM> and the maximum outer diameter D6 of the reinforcement body <NUM> in the portion adjacent to the marker <NUM> in the axial direction of the shaft <NUM> is smaller than twice the thickness T of the marker <NUM>. Accordingly, the outer diameter of the shaft <NUM> provided with the reinforcement body <NUM> and the radiopaque marker <NUM> is not too large, and the inner diameter of the shaft <NUM> is not too small. Therefore, it is possible to prevent an increase in the thickness of the shaft <NUM> while disposing the marker <NUM> in the shaft <NUM> provided with the reinforcement body <NUM>.

A thickness W1 of the outer layer <NUM> of the shaft <NUM> in the portion where the marker <NUM> is disposed and a thickness W2 of the outer layer <NUM> of the shaft <NUM> in the portion adjacent to the marker <NUM> in the axial direction X of the shaft <NUM> may be the same. Accordingly, it is possible to prevent an increase in the thickness of the shaft <NUM> while making the thicknesses W1 and W2 of the outer layer <NUM> uniform regardless of the presence or absence of the marker <NUM>. If the thicknesses W1 and W2 of the outer layer <NUM> are sufficient, the outer layer convex portion <NUM> may not be formed depending on the presence or absence of the marker <NUM>. Therefore, although the thicknesses W1 and W2 of the outer layer <NUM> are thin and uniform, the outer diameter difference (D1-D2) may be smaller than the thickness of the marker <NUM>.

The marker <NUM> includes at least one convex portion <NUM> on at least an inner surface side. Accordingly, the marker <NUM> is firmly fixed to the shaft <NUM>. Therefore, detachment of the marker <NUM> from the shaft <NUM> can be prevented.

The effective length of the shaft <NUM> is <NUM> or more. Accordingly, the catheter <NUM> can easily reach the artery of the lower limb from the artery of the arm.

The invention is not limited to the embodiment described above, and various modifications can be made by those skilled in the art within a scope of the technical idea of the invention. For example, in the embodiment described above, the number of markers <NUM> disposed in the shaft <NUM> is one, but may be two or more. The catheter <NUM> may be inserted from a blood vessel other than the artery of the arm. The catheter <NUM> may be used for the treatment or the diagnosis of the blood vessel other than the artery of the lower limb. The catheter <NUM> may be inserted into a bile duct, trachea, esophagus, urethra, or other biological lumens or a lumen in a living body and used for the treatment, the diagnosis, or the like.

As in another modification (not falling under the scope of the claims) shown in <FIG>, the inner diameter D4 of the shaft <NUM> in the portion where the marker <NUM> is disposed may be smaller than the inner diameter D3 of the adjacent portion <NUM> adjacent to the marker <NUM> in the axial direction X of the shaft <NUM>. The inner diameter difference (D3-D4), which is the difference between the inner diameter D3 and the inner diameter D4, is preferably smaller than twice the thickness T of the marker <NUM>. Accordingly, the inner diameter of the shaft <NUM> provided with the reinforcement body <NUM> and the radiopaque marker <NUM> is not too small. Therefore, it is possible to prevent an increase in the thickness of the shaft <NUM> while disposing the marker <NUM> in the shaft <NUM> provided with the reinforcement body <NUM>. By preventing an increase in the thickness of the shaft <NUM>, the inner diameter of the shaft <NUM> can be made as large as possible while the outer diameter of the shaft <NUM> can be made as small as possible. Such a catheter <NUM> is particularly effective when a blood vessel (for example, the radial artery) to be introduced is thin and a blood vessel (for example, the artery of the lower limb) to be treated or diagnosed is thick.

One of the outer diameter difference (D1-D2) and the inner diameter difference (D3-D4) alone may be smaller than twice the thickness T of the marker <NUM>. Alternatively, both the outer diameter difference (D1-D2) and the inner diameter difference (D3-D4) may be smaller than twice the thickness T of the marker <NUM>.

Claim 1:
A catheter (<NUM>) comprising:
a shaft (<NUM>) including a lumen (<NUM>) communicating from a distal end to a proximal end, wherein
the shaft (<NUM>) includes
a reinforcement body (<NUM>) including a plurality of wires (<NUM>) that are disposed on at least a part between an inner surface (<NUM>) of the shaft (<NUM>) forming the lumen (<NUM>) and an outer surface (<NUM>) of the shaft (<NUM>) and that are braided in a tubular shape, and
at least one or more radiopaque markers (<NUM>) that are disposed between the reinforcement body (<NUM>) and the outer surface (<NUM>),
a difference (D1 - D2) between an outer diameter (D1) of the shaft (<NUM>) in a portion where the marker (<NUM>) is disposed and an outer diameter (D2) of the shaft (<NUM>) in a portion adjacent to the marker (<NUM>) in an axial direction of the shaft (<NUM>) is defined as an outer diameter difference, and
a difference (D3 - D4) between an inner (D3) diameter of the shaft (<NUM>) in the portion adjacent to the marker (<NUM>) in the axial direction of the shaft (<NUM>) and an inner diameter (D4) of the shaft (<NUM>) in the portion where the marker (<NUM>) is disposed is defined as an inner diameter difference ( D3 - D4), and
at least one of the outer diameter difference and the inner diameter difference is smaller than twice a thickness (T) of the marker (<NUM>), i.e. (D1 - D2) < 2T and/or (D3 - D4) < 2T, and/or
a difference (D5 - D6) between a maximum outer diameter (D5) of the marker (<NUM>) and a maximum outer diameter (D6) of the reinforcement body (<NUM>) in a portion adjacent to the marker (<NUM>) in an axial direction of the shaft (<NUM>) is smaller than twice a thickness (T) of the marker (<NUM>), i.e. (D5 - D6) < <NUM> T,
characterized in that
a plurality of concave portions (<NUM>) and a plurality of convex portions (<NUM>) are randomly formed on the marker (<NUM>).