CATHETER

A catheter includes an outward protruding portion provided at a distalmost end portion and protruding outward in a radial direction; and an inward protruding portion provided at the distalmost end portion and protruding inward in the radial direction.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2023-34353 filed on Mar. 7, 2023, the entire content of which is incorporated herein by reference.

TECHNOLOGICAL FIELD

The present invention generally relates to a catheter.

BACKGROUND DISCUSSION

A guiding catheter is one kind of catheter and is a catheter that may be used when a balloon catheter or the like for treating a coronary artery of a heart, a lower limb artery, or the like is inserted to a target site. An example is disclosed in Japanese Patent Application Publication No. 2006-288670 (JP 2006-288670 A).

SUMMARY

In particular, in a guiding catheter used for intravascular treatment of a coronary artery, a lower limb artery, or the like, since the diameter of the blood vessel that is a treatment target is large, it is preferable that in order to select a treatment device having a large outer diameter or to deliver a plurality of treatment devices to a treatment target site at once, or in order to deliver more treatment devices to a distal end at once, the inner diameter of the guiding catheter is increased to make the thickness of the guiding catheter thin.

In such a guiding catheter that is thin, a distalmost end portion has a round shape to avoid damage to the blood vessel, but since the guiding catheter is thin, there is a possibility that when the catheter is advanced to the vicinity of the treatment target site, the catheter unintentionally scrapes, for example, tissues such as plaque present on a blood vessel wall and accumulated in an abdominal aorta.

The catheter disclosed here is capable of suppressing scraping of tissues such as plaque present on a blood vessel wall in the catheter that is thin.

The disclosed catheter that is configured to achieve the result described above includes the following. A catheter having a hollow shape, including: an outward protruding portion provided at a distalmost end portion and protruding outward in a radial direction; and an inward protruding portion provided at the distalmost end portion and protruding inward in the radial direction.(2) The catheter according to (1) further including a distal end tip, in which the outward protruding portion and the inward protruding portion are provided at the distal end tip.(3) The catheter according to (1) or (2), in which a distal end portion of the outward protruding portion has a round shape.(4) The catheter according to any one of (1) to (3), in which a distal end portion of the inward protruding portion has a round shape.(5) The catheter according to any one of (1) to (4), wherein the catheter is configured to satisfy the following relational expressions

d1<d2, and

wherein D1is a maximum outer diameter of the distalmost end portion, d1is a minimum inner diameter of the distalmost end portion, T1is a maximum thickness of the distalmost end portion, D2is an outer diameter of a proximal portion provided on a proximal end side with respect to the distalmost end portion, d2is an inner diameter of the proximal portion, and T2is a thickness of the proximal portion.

According to the catheter configured as described above, only the distalmost end portion can be made thick while the proximal portion provided on the proximal end side with respect to the distalmost end portion is made thin. Therefore, it is possible to provide the guiding catheter capable of suppressing scraping of tissues such as plaque present on a blood vessel wall in the guiding catheter that is thin.

DETAILED DESCRIPTION

Hereinafter, a catheter1according to a disclosed embodiment, representing one example of the new catheter disclosed here, will be described with reference toFIGS.1to3.FIG.1is an overall view illustrating the catheter1according to the embodiment.FIG.2is a sectional front view illustrating the catheter1according to the present embodiment.FIG.3is a sectional front view illustrating the vicinity of a distal end of the catheter1according to the present embodiment.

The catheter1illustrated inFIG.1is used as, for example, a guiding catheter that guides a treatment catheter (device), such as a dilation catheter (balloon catheter) for PTCA or a catheter (catheter for transporting a stent) for conveying a stent in a reduced diameter state to a stenosed site, increasing the diameter at the stenosed site, and indwelling the stent to widen and maintain the stenosed site, to a target site such as a stenosed site of a coronary artery or a lower limb artery.

As illustrated inFIGS.1to3, the catheter1is an elongated tube-shaped member and includes a tube10; a distal end tip20that is flexible and that is provided on a distal end side of the tube10; a hub30provided on a proximal end side of the tube10; and a strain relief40provided on the distal end side of the hub30.

The tube10is formed of a tubular body having flexibility. A lumen10H is formed in the tube10over the entire length of the tube10. The lumen10H is open at a distal end of the distal end tip20.

The tube10includes an inner layer disposed on an inner surface side; an outer layer disposed around an outer periphery of the inner layer; and a reinforcing material layer disposed inside the outer layer.

It is preferable that the outer layer is more flexible on the distal end side than on the proximal end side. With such a configuration, the tube10can gradually increase in flexibility in a distal end direction, and can be more safely inserted into a blood vessel while ensuring sufficient pushability and torque transmission to the distal end side during an operation of inserting the tube10into the blood vessel.

Examples of the material constituting the outer layer include various thermoplastic elastomers such as styrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, trans-polyisoprene, fluororubber, and chlorinated polyethylene-based thermoplastic elastomers. One or a combination of two or more of these materials (polymer alloy, polymer blend, laminate, or the like) can be used.

It is preferable that the constituent material from which the inner layer is fabricated is a material that allows at least a portion in contact with a device such as a treatment catheter or a guide wire to have low friction when the device is inserted into the lumen10H. According to this configuration, the device inserted into the tube10is movable in a longitudinal direction with smaller sliding resistance, and operability can be improved. Specifically, examples of the constituent material from which the inner layer may be fabricated include a fluorine-based resin material such as polytetrafluoroethylene (PTFE).

The reinforcing material layer includes a plurality of reinforcing wires that reinforce the tube10. Examples of the reinforcing wire include a spiral or net-shaped reinforcing wire. The reinforcing wire is made of metal such as stainless steel. As specific examples, reinforcing wires are formed by crushing stainless steel wires into a flat plate shape so as to make the thickness of the tube10thin in a radial direction, and by spiraling or weaving (braided body) a plurality of approximately 8 to 32 stainless steel wires. It is preferable that the number of the reinforcing wires is set to a multiple of 8 to implement reinforcement in a tubular shape in a well-balanced manner.

Since the reinforcing wires uniformly receive external stress by being formed into a flat plate compared to an ellipse, physical properties become constant.

It should be noted that the number of the layers constituting the tube10or the constituent material of each layer may be different along the longitudinal direction of the tube10. For example, in order to make a portion on the distal end side of the tube10more flexible, the number of the layers can be reduced, a more flexible material can be used, or the disposition of a reinforcing material can be omitted only at the portion.

Since the insertion of the catheter1into a body is performed while confirming the position thereof under X-ray fluoroscopy, it is preferable that a radiopaque material (X-ray contrast agent) is blended with the constituent material of an outer layer12. As the radiopaque material, for example, barium sulfate, bismuth oxide, tungsten, or the like can be used. Furthermore, the proportion of blending of the radiopaque material with the constituent material of the outer layer12is preferably 30 to 80 wt %.

In addition, such a radiopaque material is not limited to being present over the entire length of the tube10, and may be present in a part of the tube10, for example, in only a distal end portion or only the distal end tip20.

The distal end portion of the tube10is curved in a desired shape suitable for a site into which the distal end portion of the tube10is inserted, such as a left coronary artery and a right coronary artery. In particular, the distal end portion has a shape that facilitates the operation of engaging with a coronary ostium (engagement operation), or a shape that can more reliably maintain a state of engagement with the coronary ostium (engagement), but may have a linear shape without the noted distal end shape when used for lower limb artery or the like.

The distal end tip20is connected to a distal end of the tube10. The distal end tip20is made of a material having high flexibility. By providing the distal end tip20, the tube10is allowed to smoothly and safely travel in a curved, bent, or branched blood vessel.

As illustrated inFIGS.1to3, the distal end tip20includes an outward protruding portion21provided at a distalmost end portion20A and protruding outward in the radial direction; an inward protruding portion22provided at the distalmost end portion20A and protruding inward in the radial direction; and an extension portion23provided on the proximal end side of the distalmost end portion20A and extending in an axial direction. The outward protruding portion21and the inward protruding portion22are disposed to have the same length along the axial direction. In the present specification, an axial region in which the outward protruding portion21and the inward protruding portion22are provided is referred to as the “distalmost end portion20A”. The distal end tip20is provided with a lumen communicating with the lumen10H of the tube10.

A distal end portion21A of the outward protruding portion21has a round (rounded) shape. According to this configuration, since the distal end portion21A has a round shape, compared to a configuration not having a round shape, it is possible to suppress scraping of tissues such as plaque present on a blood vessel wall when the catheter1is moved to the distal end side (in the distal or forward direction).

A proximal end portion21B of the outward protruding portion21has a round (rounded) shape. According to this configuration, since the proximal end portion21B has a round shape, compared to a configuration not having a round shape, it is possible to suppress scraping of tissues such as plaque present on a blood vessel wall when the catheter1is moved to the proximal end side (in the proximal or rearward direction).

A distal end portion22A of the inward protruding portion22has a round (rounded) shape. According to this configuration, since the distal end portion22A has a round shape, compared to a configuration not having a round shape, it is possible to suppress scraping of tissues such as plaque present on a blood vessel wall when the catheter1is moved to the distal end side (in the distal or forward direction). Thus, as shown inFIG.3, the outer peripheral surface of the outward protruding portion21intersects the axially facing distal end surface (left facing end surface inFIG.3) at rounded corners21A and22A.

A proximal end portion22B of the inward protruding portion22has a round (rounded) shape. According to this configuration, since the proximal end portion22B has a round shape, compared to a configuration not having a round shape, it is possible to suppress scraping of tissues such as plaque present on a blood vessel wall when the catheter1is moved to the proximal end side (in the proximal or rearward direction).

As described above, since the distal end tip20includes the outward protruding portion21and the inward protruding portion22, it is possible to suppress scraping of tissues such as plaque present on a blood vessel wall when the catheter1is moved.

The configuration including the outward protruding portion21and the inward protruding portion22described above can be rephrased or described in a different way as follows.

As illustrated inFIG.3, when a maximum outer diameter of the distalmost end portion20A is D1, a minimum inner diameter of the distalmost end portion20A is d1, a maximum thickness of the distalmost end portion20A is T1, an outer diameter of the tube10(corresponding to a proximal portion) provided on the proximal end side with respect to the distalmost end portion20A is D2, an inner diameter of the tube10is d2, and a thickness of the tube10is T2, the dimensional relationship can be expressed by a relational expression of D1>D2, d1<d2, and T1>T2.

The maximum outer diameter D1of the distalmost end portion20A is preferably 1.4 to 3.1 mm, the minimum inner diameter d1of the distalmost end portion20A is preferably 1.2 to 3 mm, and the maximum thickness T1of the distalmost end portion20A is preferably 0.09 to 0.4 mm.

In addition, the outer diameter D2of the tube10is preferably 1.35 mm or more and 3 mm or less. In a case where the outer diameter D2is too large, the operability of the tube10deteriorates when inserted and moved in an artery, and the burden on a patient increases, which is a risk.

In addition, the inner diameter d2of the tube10is preferably 1.2 mm or more and 2.85 mm or less. In a case where the inner diameter d2is too small, a treatment catheter or the like that can be inserted into the tube10is also reduced in outer diameter accordingly, and the range of selection of devices that may be inserted and used is limited, which is not preferable.

In addition, the thickness T2of the tube10is preferably 0.05 to 0.3 mm.

In the tube10, d2/D2that is the ratio of the inner diameter to the outer diameter is 0.85 or more and 0.95 or less, and preferably 0.87 or more and 0.93 or less. In a case where the value of d2/D2is too small, the result is that the thickness of the tube10becomes thick and the inner diameter becomes small, whereby devices that can be introduced into the tube10are limited. In addition, in a case where the value of d2/D2is too large, the thickness of the tube10cannot be sufficiently obtained (the thickness of the tube is insufficient), so that the backup force becomes weak and kink resistance during use decreases.

In addition, the amount of outward protrusion of the outward protruding portion21with respect to the extension portion23is preferably more than 0 to 0.3 mm, and more preferably 0.05 to 0.1 mm. The amount of inward protrusion of the inward protruding portion22with respect to the extension portion23is preferably more than 0 to 0.3 mm, and more preferably 0.05 to 0.1 mm.

The extension portion23is provided on the proximal end side of the distalmost end portion20A. An outer diameter of the extension portion23is substantially the same as the outer diameter D2of the tube10, and an inner diameter of the extension portion23is substantially the same as the inner diameter d2of the tube10.

A length L1of the distalmost end portion20A along the axial direction is preferably more than 0 to 1 mm, and more preferably 0.05 to 0.3 mm. A length L2of the extension portion23along the axial direction is preferably more than 0 to 5 mm, and more preferably 0.5 to 1 mm.

It should be noted that since only the distalmost end portion20A is thick and the proximal end side of the distalmost end portion20A is thin in the catheter1described above, it is easy to cause a large treatment device or a plurality of treatment devices to protrude from the inside of the catheter1.

Examples of the material constituting the distal end tip20include various rubber materials such as natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, silicone rubber, fluororubber, and styrene-butadiene rubber or various thermoplastic elastomers such as styrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, trans-polyisoprene, fluororubber, and chlorinated polyethylene-based thermoplastic elastomers.

In addition, the radiopaque material (X-ray contrast agent) as described above may be blended with the constituent material of the distal end tip20.

The hub30is mounted (fixed) on a proximal end of the tube10. A lumen communicating with the lumen10H is formed in the hub30. This lumen has an inner diameter substantially equal to an inner diameter of the lumen10H, and is continuous with an inner surface of a proximal end portion of the lumen10H without creating a step or the like.

For example, an elongated object (wire-shaped body) such as a guide wire, a catheter (for example, a balloon catheter for PTCA or a catheter for conveying a stent), an endoscope, an ultrasonic probe, or a temperature sensor can be inserted or removed from the hub30, or various liquids such as a contrast agent (X-ray contrast agent), a drug solution, and a physiological salt solution can be injected into the hub30. In addition, for example, the hub30can also be connected to other instruments such as a Y-shaped branch connector.

As described above, the catheter1according to the present embodiment is the catheter1having a hollow shape, and includes the outward protruding portion21provided at the distalmost end portion20A and protruding outward in the radial direction and the inward protruding portion22provided at the distalmost end portion20A and protruding inward in the radial direction. According to the catheter1configured in this manner, only the distalmost end portion20A can be made thick (relatively thick) while the proximal portion (corresponding to the tube10or the extension portion23) provided on the proximal end side with respect to the distalmost end portion20A is made thin (relatively thin). Therefore, it is possible to provide the catheter1capable of suppressing scraping of tissues such as plaque present on a blood vessel wall in the catheter1that is thin.

In addition, the catheter1includes the distal end tip20, and the outward protruding portion21and the inward protruding portion22are provided at the distal end tip20. According to the catheter1configured in this manner, since the outward protruding portion21and the inward protruding portion22are provided at the distal end tip20that is more flexible, it is possible to more suitably suppress scraping of tissues such as plaque present on a blood vessel wall.

In addition, the distal end portion21A of the outward protruding portion21and the distal end portion22A of the inward protruding portion22have a round (rounded) shape. According to the catheter1configured in this manner, it is possible to more suitably suppress scraping of tissues such as plaque present on a blood vessel wall.

In addition, when the maximum outer diameter of the distalmost end portion20A is D1, the minimum inner diameter of the distalmost end portion20A is d1, the maximum thickness of the distalmost end portion20A is T1, the outer diameter of the tube10(corresponding to the proximal portion) provided on the proximal end side with respect to the distalmost end portion20A is D2, the inner diameter of the tube10is d2, and the thickness of the tube10is T2, the dimensional relationship is expressed by a relational expression of D1>D2, d1<d2, and T1>T2. According to the catheter1configured in this manner, only the distalmost end portion20A can be made thick (relatively thick) while the proximal portion (corresponding to the tube10or the extension portion23) provided on the proximal end side with respect to the distalmost end portion20A is made thin (relatively thin). Therefore, it is possible to provide the catheter1capable of suppressing scraping of tissues such as plaque present on a blood vessel wall in the catheter1that is thin.

The catheter1disclosed here has been described above through the embodiment; however, the present invention is not limited to only the configurations described in the embodiment, and can be changed as appropriate within the scope of the claims.

For example, in the above-described embodiment, the outward protruding portion21and the inward protruding portion22are provided at the distal end tip20. However, as illustrated inFIG.4, a catheter2according to a modification example may have a configuration in which the distal end tip20is not provided and an outward protruding portion111and an inward protruding portion112are provided at a distalmost end portion110A of a tube110.

In addition, in the above-described embodiment, the distal end portion21A of the outward protruding portion21, the proximal end portion21B of the outward protruding portion21, the distal end portion22A of the inward protruding portion22, and the proximal end portion22B of the inward protruding portion22have a round (rounded) shape. However, the distal end portion of the outward protruding portion, the proximal end portion of the outward protruding portion, the distal end portion of the inward protruding portion, and the proximal end portion of the inward protruding portion may not have a round (rounded) shape.

The detailed description above describes embodiments of a catheter representing an example of the new catheter disclosed here. The invention is not limited, however, to the precise embodiment and variations described. Various changes, modifications and equivalents can be effected by one skilled in the art without departing from the spirit and scope of the invention as defined in the accompanying claims. It is expressly intended that all such changes, modifications and equivalents that fall within the scope of the claims are embraced by the claims.