Patent Description:
In particular the present invention relates to a medical tube according to the preamble of claim <NUM>, such as it is e.g. known from <CIT> or <CIT>.

There are various types of medical tubes (for example, catheters) to be inserted into a living body depending on purposes. For example, a sheath for an introducer sheath used to percutaneously introduce a treatment catheter, or the like into a living body represent a blood vessel indwelling catheter. In general, such a sheath includes a flexible tube-shaped main sheath body (main catheter body), a hub connected to a proximal portion of the main sheath body, and a strain relief that surrounds a predetermined range of a proximal side of the main sheath body to suppress the occurrence of a kink (for example, see <CIT>). Note that the strain relief is provided to another type of catheter to suppress the occurrence of a kink at a proximal side of a main catheter body.

Incidentally, a medical tube such as a catheter requires compatibility between reducing a diameter to achieve a low invasion and ensuring an inner diameter to achieve a technique, and thinning of a tube-shaped main body included in a main body of the medical tube is one of the solutions to the requirement. However, when the tube-shaped main body is merely thinned, the possibility that a kink will occur at the time of operating the medical tube increases.

The invention has been conceived in view of the above problem, and an object of the invention is to provide a medical tube capable of increasing kink resistance of a tube-shaped main body while reducing a thickness.

To achieve the above-mentioned object, a medical tube according to independent claim <NUM> is provided. The dependent claims relate to advantageous embodiments.

According to the medical tube of the invention configured as described above, since the flexible portion is provided in a front-rear range including the most distal portion of the strain relief, flexibility for bending of the tube-shaped main body increases in the flexible portion. Therefore, it is possible to increase kink resistance of the tube-shaped main body while reducing a wall thickness.

In the above-described medical tube, the groove extending in the circumferential direction may be a helical groove. According to this configuration, it is possible to easily form a groove extending in the circumferential direction over a predetermined range of the tube-shaped main body.

In the above-described medical tube, the flexible portion may include a plurality of sub-regions, each of which has a different pitch or width in the groove, and the sub-region on a distal side may be more flexible in the sub-regions adjacent to each other. According to this configuration, flexibility increases in stages toward the distal side, and thus it is possible to effectively suppress the occurrence of a kink.

In the above-described medical tube, at least one boundary portion between the sub-regions may be positioned on a distal side from the most distal portion of the strain relief. According to this configuration, flexibility increases in stages toward the distal side in a front-rear region including the most distal portion of the strain relief, and thus it is possible to more effectively suppress the occurrence of a kink.

In the above-described medical tube, the medical tube may be an introducer sheath indwelled in a lumen of a living body to introduce another elongated medical instrument into the body. In this way, it is possible to provide an introducer sheath excellent in kink resistance.

According to the medical tube of the invention, it is possible to increase kink resistance of the tube-shaped main body while reducing a wall thickness.

Hereinafter, a medical tube according to the invention will be described using a preferred embodiment with reference to accompanying drawings.

<FIG> is a partially-omitted schematic diagram of a catheter <NUM> included in a medical tube according to an embodiment of the invention. The catheter <NUM> is a medical instrument inserted into a lumen in a living body such as a blood vessel, and is configured as an introducer sheath <NUM> in the present embodiment. The introducer sheath <NUM> is a device used in combination with a dilator (not illustrated) to introduce a treatment catheter, or the like percutaneously into the living body. Note that the catheter <NUM> may be configured as a catheter other than the introducer sheath <NUM>, for example, a treatment catheter such as a balloon catheter, a guiding catheter, or the like.

As illustrated in <FIG>, the catheter <NUM> includes a main catheter body <NUM> (tube-shaped main body), a hub <NUM>, and a strain relief <NUM>. The main catheter body <NUM> is a flexible tube-shaped member, and is also referred to as a shaft. In the case of the introducer sheath <NUM>, the main catheter body <NUM> is also referred to as a sheath tube. The main catheter body <NUM> has a lumen <NUM> opened at a distal end and a proximal end of the main catheter body <NUM>.

A length of the main catheter body <NUM> varies according to type (intended use) of the catheter <NUM>. In the case of the introducer sheath <NUM>, the length is in a range of about <NUM> to <NUM>.

Examples of a material included in the main catheter body <NUM> include polyvinyl chloride-based resin, a urethane resin such as polyurethane, an olefin-based resin such as polyethylene, polyamide, a synthetic resin such as ethylene-vinyl acetate copolymer, silicone rubber, and latex rubber.

The hub <NUM> is a member that includes a lumen <NUM> connected to a proximal portion 12A of the main catheter body <NUM> to communicate with the lumen <NUM> of the main catheter body <NUM>. A protruding portion <NUM>, a diameter of which is reduced with respect to a body portion <NUM> of the hub <NUM>, is provided to protrude in a distal end direction at a distal end of the hub <NUM>, and the proximal portion 12A of the main catheter body <NUM> is inserted into and fixed to an inner peripheral portion of a distal end of the protruding portion <NUM>. Examples of a constituent material of the hub <NUM> include a rigid resin such as polypropylene, ABS, and polycarbonate.

A valve body <NUM> for preventing a leakage of a liquid from the inside of the hub <NUM> is disposed inside the hub <NUM>. A hollow fixing member <NUM> is screwed with a proximal portion of the hub <NUM>, and the valve body <NUM> is fixed inside the hub <NUM> when the valve body <NUM> is interposed between a distal surface of the fixing member <NUM> and a step portion 14a formed inside the hub <NUM>. Note that a scheme of fixing the fixing member <NUM> to the proximal portion of the hub <NUM> is not restricted to screwing, and a structure capable of interposing the valve body <NUM> between the hub <NUM> and the fixing member <NUM> may be used. For example, the fixing member <NUM> may be bonded or heat-welded to the hub <NUM> such that the valve body <NUM> is interposed between the hub <NUM> and the fixing member <NUM>. In addition, instead of not providing the valve body <NUM> in the hub <NUM>, the valve body <NUM> may be provided in a connector member connectable to a proximal end of the hub <NUM>.

The valve body <NUM> has an elastic material (for example, silicone rubber). A slit (not illustrated), into which a dilator or another catheter can be inserted, is formed in the valve body <NUM>. The valve body <NUM> may prevent a body fluid (blood, or the like) flowing in the lumen <NUM> of the hub <NUM> through the main catheter body <NUM> from leaking out in a state in which the dilator, or the like is inserted into the slit.

A flexible side tube <NUM> is connected to a side portion of the hub <NUM>. In an illustrated example, one end of the side tube <NUM> is connected to a side port <NUM> extruding outward from the side portion of the hub <NUM>. A lumen <NUM> of the side tube <NUM> communicates with the lumen <NUM> of the hub <NUM> through a side hole 14b provided in the hub <NUM>.

A three-way stopcock <NUM> is provided at an end portion 22b of the side tube <NUM> on the opposite side from an end portion 22a connected to the hub <NUM>. For example, the three-way stopcock <NUM> includes a port <NUM> for discharging air, a port <NUM> for chemical injection to which a syringe, or the like (not illustrated) is connected, a port <NUM> connected to the end portion 22b of the side tube <NUM>, and a cock <NUM> for switching communication states of the ports <NUM>, <NUM>, and <NUM>. Note that the port <NUM> and the port <NUM> are not restricted to uses for discharging air and chemical injection, and use is not particularly restricted.

The strain relief <NUM> has a function of preventing or suppressing a kink (bending) at a proximal side of the main catheter body <NUM> (specifically, an interlock portion of the main catheter body <NUM> and the hub <NUM> and a region around the interlock portion). As illustrated in <FIG>, the strain relief <NUM> is a hollow member having flexibility which is supported at a distal portion of the hub <NUM> (protruding portion <NUM>) and surrounds a predetermined range of the proximal side of the main catheter body <NUM>.

An outer diameter of the strain relief <NUM> is relatively large at a proximal side thereof and relatively small at a distal side thereof, and the outer diameter gradually decreases toward the distal side. A wall thickness of the strain relief <NUM> decreases toward the distal side. A proximal portion of the strain relief <NUM> is fit onto the protruding portion <NUM> provided at the distal end of the hub <NUM>. In this way, the strain relief <NUM> is supported by the distal portion of the hub <NUM>.

Note that a bulge portion 19a annularly extending in a circumferential direction is formed on an outer peripheral surface of the protruding portion <NUM> in <FIG>, and the strain relief <NUM> is prevented from falling out of the protruding portion <NUM> when the bulge portion 19a is engaged with an annular depression 16a formed on an inner peripheral surface of the proximal portion of the strain relief <NUM>.

Examples of a constituent material of the strain relief <NUM> include a thermoplastic resin such as styrene resin, olefin resin, and polyester resin.

As illustrated in <FIG>, the main catheter body <NUM> includes a flexible portion <NUM> whose flexibility for bending is increased compared to front and rear parts thereof by forming at least one groove <NUM> extending in the circumferential direction in an outer circumferential portion over a predetermined range from a distal side from a most distal portion <NUM> of the strain relief <NUM> to a proximal side from the most distal portion <NUM>.

The groove <NUM> is a portion dented by a depth H with respect to an outer diameter D (reference outer diameter) of the main catheter body <NUM>. Therefore, a wall thickness of a portion of the main catheter body <NUM> in which the groove <NUM> is formed is thinner than a wall thickness T of a portion other than the flexible portion <NUM> by the depth H of the groove <NUM>. In this way, the flexible portion <NUM> has higher flexibility than that of the front and rear parts of the flexible portion <NUM> in the main catheter body <NUM>.

In the present embodiment, the groove <NUM> extending in the circumferential direction is a helical groove <NUM>. The helical groove <NUM> may be a single helix or a multiple helix such as a double helix. The helical groove <NUM> may not be a groove which is continuous from a distal end to a proximal end of the flexible portion <NUM>, and may be intermitted at one or more places in the middle. The groove <NUM> may be an annular groove instead of the helical groove <NUM>, and a plurality of (multiple) annular grooves may be formed in the outer circumferential portion of the main catheter body <NUM> at intervals in an axial direction.

For example, the depth H of the groove <NUM> with respect to a thickness T of a wall that forms the main catheter body <NUM> is set to <NUM> to <NUM>%, preferably <NUM> to <NUM>%. Alternatively, even though the depth H of the groove <NUM> depends on the thickness T of the wall that forms the main catheter body <NUM>, for example, the depth H is set to about <NUM> to <NUM>.

In the invention, a distance L1 from the most distal portion <NUM> of the strain relief <NUM> to a most distal portion of the flexible portion <NUM> (a most distal portion of the groove <NUM>) is set to <NUM> to <NUM>, preferably <NUM> to <NUM>. For example, a distance L2 from the most distal portion <NUM> of the strain relief <NUM> to a most proximal portion of the flexible portion <NUM> (a most proximal portion of the groove <NUM>) is set to <NUM> to <NUM>, preferably <NUM> to <NUM>.

For example, the helical groove <NUM> may be formed by helicoidally winding a linear member (wire, or the like) around an outer peripheral surface of a tube-shaped compact, which is supported by a spindle and has the outer diameter D (the main catheter body <NUM> before the flexible portion <NUM> is formed), in a predetermined range in an axial direction, heating the linear member, and then removing the linear member. Note that the groove <NUM> may be formed by helicoidally or annularly scraping the outer peripheral surface of the compact instead of using a method of using the linear member. Alternatively, the main catheter body <NUM> including the groove <NUM> may be manufactured by injection molding using an injection molding tool provided with a shape corresponding to the groove <NUM> in advance.

The catheter <NUM> according to the present embodiment is basically configured as described above, and operations and effects thereof will be described below.

As described in the foregoing, the catheter <NUM> is configured as the introducer sheath <NUM>. In the use of the introducer sheath <NUM>, the introducer sheath <NUM> is combined with a dilator (not illustrated). Specifically, an assembly (introducer) in a state in which the dilator is inserted into the introducer sheath <NUM> punctures a blood vessel of a patient such that a distal end of the introducer sheath <NUM> secures the blood vessel. Thereafter, the main catheter body <NUM> is further inserted into the blood vessel and inserted up to a portion around the most distal portion <NUM> of the strain relief <NUM>, and then the dilator is pulled out of the introducer sheath <NUM>. A length in which the main catheter body <NUM> is inserted into the blood vessel is set to a predetermined length.

Subsequently, another device such as a treatment catheter (balloon catheter, or the like) or a guiding catheter is introduced through the introducer sheath <NUM> while being led by a guide wire (not illustrated) inside the blood vessel. Further, the device is advanced up to a predetermined region inside the living body, and treatment is performed.

Incidentally, the proximal-side portion of the main catheter body <NUM> (the interlock portion of the main catheter body <NUM> and the hub <NUM>) is exposed to the outside of the body during a surgery. Thus, when the main catheter body <NUM> is inserted into the blood vessel, or when the hub <NUM> may be lifted to insert and remove another device from a proximal end opening of the hub <NUM>, bending stress acts on the proximal-side portion of the main catheter body <NUM>. The strain relief <NUM> is provided to suppress the occurrence of a kink in the proximal-side portion of the main catheter body <NUM> due to bending stress at this time.

However, a kink occurs when the amount of change of bending of the main catheter body <NUM> is greater than or equal to a certain extent. In particular, around a distal portion of the strain relief <NUM>, that is, around a boundary portion between a portion covered with the strain relief <NUM> and a portion not covered with the strain relief <NUM> in the main catheter body <NUM>, bending rigidity greatly varies, and stress is easily concentrated. Thus, a kink easily occurs.

In this regard, in the catheter <NUM>, the flexible portion <NUM>, flexibility of which is increased by the groove <NUM>, is provided in a front-rear range including the most distal portion <NUM> of the strain relief <NUM> in the main catheter body <NUM>. The flexible portion <NUM> has higher flexibility than that of another portion of the main catheter body <NUM> in which the groove <NUM> is not provided, that is, a portion on a distal side and a portion on a proximal side from the flexible portion <NUM>.

Since the flexible portion <NUM> is provided in the main catheter body <NUM>, the main catheter body <NUM> having the flexible portion <NUM> is more flexible with respect to bending when compared at the same outer diameter D. That is, when compared at the same outer diameter D, the amount of change of bending at which a kink may occur (allowed amount of change) is larger in the main catheter body <NUM> having the flexible portion <NUM> than in a conventional main catheter body not having the flexible portion <NUM>.

As described above, in the catheter <NUM> of the invention, a more flexible portion, that is, a less rigid portion than another portion in the axial direction is provided in a particular region on the proximal side of the main catheter body <NUM> and is allowed to be easily bent, thereby suppressing stress concentration due to bending, and inhibiting the occurrence of a kink. Therefore, according to the catheter <NUM>, kink resistance of the main catheter body <NUM> may be increased while reducing a wall thickness.

In particular, in the case of the present embodiment, the groove <NUM>, which is provided in the outer circumferential portion of the main catheter body <NUM> and extends in the circumferential direction, is the helical groove <NUM>. As described in the foregoing, for example, since the helical groove <NUM> is easily formed by winding the linear member around the outer circumferential portion of the tube-shaped compact, it is possible to easily manufacture the main catheter body <NUM> having the flexible portion <NUM> over the predetermined range in the axial direction.

As described in the foregoing, when the introducer sheath <NUM> is indwelled inside the blood vessel, the main catheter body <NUM> is inserted into the blood vessel up to a portion around the most distal portion <NUM> of the strain relief <NUM>. For this reason, in particular, a portion around the strain relief <NUM> of the main catheter body <NUM> fixedly comes into contact with a skin or a blood vessel wall, and a degree of curvature locally increases easily in the portion. Thus, a kink easily occurs. For this reason, the invention capable of suppressing a kink in the proximal-side portion of the main catheter body <NUM> is suitable for the introducer sheath <NUM>.

A plurality of sub-regions 30A and 30B having different groove pitches may be provided as in a flexible portion <NUM> of a main catheter body 12a according to a first modified example illustrated in <FIG>. In this case, the sub-region 30A on a distal side is more flexible in the sub-regions 30A and 30B adjacent to each other, and at least one boundary portion C between the sub-regions 30A and 30B is positioned on the distal side from a most distal portion <NUM> of a strain relief <NUM>.

Referring to <FIG>, specifically, the flexible portion <NUM> includes the first sub-region 30A in which a groove 32A is formed at a relatively small pitch P1 and the second sub-region 30B in which a groove 32B is formed at a relatively large pitch P2. Therefore, the first sub-region 30A has higher flexibility with respect to bending than that of the second sub-region 30B. Note that a range indicated by A refers to the first sub-region 30A and a range indicated by B refers to the second sub-region 30B in <FIG>.

Meanwhile, flexibility obtained by applying rigidity of the strain relief <NUM> to the main catheter body 12a is higher in a portion from a boundary portion C between the first sub-region 30A and the second sub-region 30B to the most distal portion <NUM> of the strain relief <NUM> than in a portion from the most distal portion <NUM> of the strain relief <NUM> to a most proximal portion of the second sub-region 30B.

In the case of <FIG>, each of the grooves 32A and 32B in the first sub-region 30A and the second sub-region 30B is a helical groove. Each of the grooves 32A and 32B may correspond to a plurality of annular grooves form at intervals in an axial direction in place of the helical groove. The groove 32A of the first sub-region 30A and the groove 32B of the second sub-region 30B may communicate with each other, or may correspond to grooves independent from each other.

In the case of <FIG>, since the flexible portion <NUM>, which includes the plurality of sub-regions (the first sub-region 30A and the second sub-region 30B) having different groove pitches, is provided, flexibility increases in stages toward the distal side in a front-rear region including the most distal portion <NUM> of the strain relief <NUM>. For this reason, it is possible to more effectively suppress the occurrence of a kink in the main catheter body 12a. Note that three or more sub-regions having different groove pitches may be provided in the main catheter body 12a.

As in a flexible portion <NUM> of a main catheter body 12b according to a second modified example illustrated in <FIG>, a first sub-region 30A may have higher flexibility with respect to bending than that of a second sub-region 30B by setting a width W1 of a groove 32A of the first sub-region 30A to be larger than a width W2 of a groove 32B of the second sub-region 30B. The same effect as that of a configuration of <FIG> is obtained by a configuration of <FIG>. Note that three or more sub-regions having different groove widths may be provided in the main catheter body 12b.

Claim 1:
A medical tube (<NUM>) comprising:
a flexible tube-shaped main body (<NUM>);
a hub (<NUM>) connected to a proximal portion of the tube-shaped main body (<NUM>); and
a strain relief (<NUM>) supported at a distal portion of the hub (<NUM>), the strain relief (<NUM>) surrounding a predetermined range of a proximal side of the tube-shaped main body (<NUM>);
the tube-shaped main body (<NUM>) includes a flexible portion (<NUM>, <NUM>, or <NUM>) whose flexibility for bending is increased by forming at least one groove (<NUM>) extending in a circumferential direction in an outer circumferential portion over a predetermined range from a distal side from a most distal portion (<NUM>) of the strain relief (<NUM>) to a proximal side from the most distal portion (<NUM>),
characterized in that
a distance (L1) from the most distal portion (<NUM>) of the strain relief (<NUM>) to a most distal portion of the flexible portion (<NUM>, <NUM>, or <NUM>) is set to <NUM> to <NUM>, preferably <NUM> to <NUM>; and
a distance (L2) from the most distal portion (<NUM>) of the strain relief (<NUM>) to a most proximal portion of the flexible portion (<NUM>, <NUM>, or <NUM>) is set to <NUM> to <NUM>, preferably <NUM> to <NUM>;
the medical tube (<NUM>) is an introducer sheath (<NUM>) indwelled in a lumen of a living body to introduce another elongated medical instrument into the body;
a length of the tube-shaped main body (<NUM>) is in a range of about <NUM> to <NUM>;
the flexible portion (<NUM>, <NUM>, or <NUM>) has higher flexibility than that of the front and rear parts of the flexible portion (<NUM>, <NUM>, or <NUM>) in the tube-shaped main body (<NUM>) and the flexible portion (<NUM>, <NUM> or <NUM>) has higher flexibility than that of another portion of the tube-shaped main body (<NUM>) in which the groove is not provided, that is, a portion on a distal side and a portion on a proximal side from the flexible portion (<NUM>, <NUM>, or <NUM>).