JP6153648B2 - catheter - Google Patents

Description

  The present invention relates to a catheter to be inserted into a blood vessel, and particularly to a catheter having outer layers having different rigidity.

  A catheter to be inserted into a blood vessel is a medical device having a thin and flexible structure. The catheter can be used for testing to diagnose a disease (for example, to identify the location of a stenosis requiring treatment or to grasp the progress of a stenosis) or for treatment to treat a disease (for example, a stenosis It is used to expand the stenosis or introduce a drug into the stenosis.

Both the examination catheter and the treatment catheter are generally a reinforcing body in which an inner layer made of resin, an outer layer made of resin coated on the outer periphery of the inner layer, and a strand made of metal are knitted between the inner layer and the outer layer. A blade. As the performance required for the catheter, there are various properties such as tip flexibility, pushability, torque rotation property, kink resistance, and followability.

For example, as a catheter considering the flexibility and pushability of the tip, the rear end of the outer layer (the main part of the catheter shaft) is formed of a highly rigid resin, while the tip of the outer layer (the tip of the catheter shaft) is flexible. A catheter having an outer layer with different rigidity by being formed of a simple resin is known (see, for example, Patent Document 1 and Patent Document 2 below).

In Patent Document 1, a blade is knitted on the outer periphery of an inner layer made of resin, and an outer layer made of a flexible resin (Shore hardness D: 35 to 45) and an outer layer made of a highly rigid resin (Shore hardness D: 65 to 65). 70) and heat-welding each other to produce outer layers having different rigidity. In Patent Document 2, a blade is knitted on the outer periphery of an inner layer made of resin, and an outer layer made of a highly rigid resin is once formed on the outer periphery of the blade. Thereafter, by removing only the front end portion of the outer layer and replacing it with an outer layer made of a flexible resin, outer layers having different rigidity are produced.

In this way, by using outer layers with different rigidity, it is possible to ensure the flexibility and pushability of the tip, while inserting the catheter into a meandering blood vessel and placing it in a curved state for a long time, There is a risk that stress concentrates on the boundary between the outer layers having different rigidity (in other words, the boundary between the main body portion and the distal end portion of the catheter shaft), and the outer layer cracks or the outer layer peels off.

For example, as shown in FIGS. 8A and 8B, a blade 260 is knitted on the outer periphery of the inner layer 240, and the outer periphery of the blade 260 is made of a first outer layer 280a made of a highly rigid resin and a flexible resin. When the catheter 100 coated with the second outer layer 280b is bent, there are the following problems. Since the adhesive strength (adhesiveness) between the first outer layer 280a and the inner layer 240 is different from the adhesive strength (adhesiveness) between the first outer layer 280b and the inner layer 240, the degree of suppressing the movement of the blade 260 is different. . The movement of the blade 260 due to the curvature (in other words, the pitch interval between the blades 260 increases) is higher than the blade 260 in the first outer layer 280a made of a highly rigid resin, and the blade in the second outer layer 280b made of a soft resin. 260 is larger (in other words, the movement amount of the blade 260 is 400a <400b). Therefore, the stress 300a that pulls the first outer layer 280a in the rear end direction and the stress 300b that pulls the second outer layer 280b in the front end direction are not balanced, and the boundary between the first outer layer 280a and the second outer layer 280b having different rigidity There was a problem that stress was concentrated to cause cracks and the second outer layer 280b was peeled off from the inner layer 240.

US Pat. No. 5,254,107 Japanese Patent No. 4741151

  The present invention has been made in view of such circumstances, and even when a catheter inserted into a blood vessel is placed in a curved state for a long time, the boundary between outer layers having different hardnesses (for example, a main body portion of a catheter shaft). It is an object of the present invention to provide a catheter that can suppress stress generated at the boundary between the main body portion and the adjacent portion adjacent to the main body portion, and can prevent cracking or peeling of the outer layer.

  The above problems are solved by the means listed below.

Aspect 1 of the present invention includes an inner layer, a blade knitted on the outer periphery of the inner layer, an intermediate layer covering the outer periphery of the blade, a first outer layer made of a resin covering the outer periphery of the intermediate layer, and the first outer layer A catheter that covers the outer periphery of the middle layer on the tip side, and a second outer layer made of a softer resin than the first outer layer, and the middle layer has a convex portion on the blade, The catheter has a contour including a recess in a gap between the adjacent blades, and a boundary between the first outer layer and the second outer layer is disposed in the recess of the middle layer.

Aspect 2 of the present invention includes a third outer layer that is coated on the front end side of the second outer layer, covers the outer periphery of the intermediate layer, and is made of a softer resin than the second outer layer. The catheter according to aspect 1, wherein the boundary with the third outer layer is disposed in the concave portion of the middle layer.

Aspect 3 of the present invention is the catheter according to aspect 1 or 2, wherein the intermediate layer is made of a resin having higher rigidity than the second outer layer.

A fourth aspect of the present invention is the catheter according to the third aspect, wherein the intermediate layer is made of a resin having higher rigidity than the first outer layer.

In the catheter according to aspect 1 of the present invention, since the boundary between the first outer layer and the second outer layer is disposed in the concave portion of the middle layer, when the catheter is bent, the rear end of the second outer layer (near the boundary) The second outer layer is caught by the convex portion of the middle layer, and the second outer layer can be further prevented from peeling off from the middle layer by the anchor effect.

In the catheter according to the second aspect of the present invention, the second outer layer and the third outer layer are provided with a third outer layer made of a resin that covers the outer periphery of the intermediate layer and is more flexible than the second outer layer on the distal side of the second outer layer. Is located in the concave portion of the middle layer, and when the catheter is bent, the rear end of the third outer layer (the third outer layer near the boundary) is caught by the convex portion of the middle layer, and the anchor effect Thus, the third outer layer can be made difficult to peel from the middle layer.

In the catheter according to aspect 3 of the present invention, the middle layer is formed of a resin having higher rigidity than the second outer layer. Therefore, even when the catheter is bent, even if the blade moves due to the bending, the movement of the blade can be suppressed because the middle layer has a certain degree of rigidity. By using the intermediate layer having a certain degree of rigidity, it becomes possible to adjust the movement of the blade that could not be suppressed by the flexible second outer layer. Further, since the middle layer extends in the axial direction with the movement of the blade, the middle layer can relieve the tensile stress caused by the blade, and the concentration of stress generated at the boundary between the first outer layer and the second outer layer can be reduced. .

In the catheter according to aspect 4 of the present invention, the middle layer is further formed of a resin having higher rigidity than the first outer layer. Therefore, when the catheter is bent, the middle layer having high rigidity can further suppress the movement of the blade due to the bending (for example, the pitch interval of the blade is widened), and the tensile stress caused by the blade is not generated. be able to.

FIG. 1 is an overall view of the catheter of the present embodiment. FIG. 2 is a view showing the catheter shaft of the present embodiment. It is the figure which removed the front-end | tip tip, a part of middle layer, and a part of outer layer for description. FIG. 3 is a cross-sectional view of the catheter shaft and the tip of the present embodiment. FIG. 4 is an enlarged cross-sectional view of the main body portion and the distal end portion of the catheter shaft of the present embodiment. 4A is a diagram illustrating a state before bending, and FIG. 4B is a diagram illustrating a state after bending. FIG. 5 is an enlarged cross-sectional view of a main body portion and a distal end portion of a catheter shaft according to another embodiment. FIG. 5A is a diagram illustrating a state before bending, and FIG. 5B is a diagram illustrating a state after bending. FIG. 6 is a view of the catheter shaft of FIG. 2 curved. FIG. 7 is a diagram showing a process of manufacturing the catheter shaft of the present embodiment. FIG. 8 is an enlarged cross-sectional view of a main body portion and a distal end portion of a conventional catheter shaft.

  The catheter 1 of the present embodiment will be described with reference to FIGS. 1 to 3, 6, and 7, the left side is a distal end side (distal side) inserted into the body, and the right side is a rear end side (proximal side, proximal end) operated by an operator such as a doctor. Side).

  A catheter 1 shown in FIG. 1 is a tubular medical device having a total length of about 1200 mm. The catheter 1 mainly includes a flexible catheter shaft 10, a distal tip 12 bonded to the distal end of the catheter shaft 10, and a connector 14 fixed to the rear end portion of the catheter shaft 10.

  As shown in FIGS. 2 and 3, the catheter shaft 10 includes an inner layer 24, a blade 26 as a reinforcing body, a middle layer 29, and an outer layer 28 in order from the inside in the radial direction.

  The inner layer 24 is made of resin, and constitutes the lumen 18 for inserting a guide wire or other catheter therein. The resin material for forming the inner layer 24 is not particularly limited, but PTFE (polytetrafluoroethylene) is used in the present embodiment.

  A blade 26 as a reinforcing body is formed on the outer periphery of the inner layer 24. As shown in FIG. 2 and FIG. 6, the blade 26 is formed by braiding a first strand 26 a and a second strand 26 b into a mesh (mesh shape). In the case of the present embodiment, a total of 16 (8 × 8) strands of eight first strands 26a and eight second strands 26b are knitted alternately. That is, the first strand 26a is wound in one direction, and the second strand 26b is wound in the other direction.

  In addition, the combination of the first strand 26a and the second strand 26b of the blade 26 is not limited to 8 × 8 as described above. For example, 4 × 4, 2 × 2 Such a symmetric combination may be used, and an asymmetric combination such as 4 × 8, 2 × 4, or the like may be employed. Further, the strand width of the first strand 26a and the strand width of the second strand 26b may be the same, or the strand width of one strand 26a may be the strand of the other strand 26b. It may be larger than the width. Furthermore, the first strand 26a and the second strand 26b are knitted by a method of alternately weaving every two (every other), but the present invention is not limited to this. You may form by the method of weaving.

  The material of the first strand 26a and the second strand 26b may be the same material or different materials. In the present embodiment, the first strand 26a made of stainless steel (SUS316) with a low melting point and the second strand 26b made of tungsten with a high melting point are used. However, the first strand 26a and the second strand The material used for the wire 26b is not particularly limited. For example, a material other than metal (for example, reinforced plastic) may be used. However, in order to make it easier for a doctor or the like to grasp the position of the catheter 1 during examination or treatment, either the first strand 26a or the second strand 26b is a heavy metal (for example, tungsten) having radiopacity. It is preferable to use a material.

  An intermediate layer 29 made of resin is formed on the outer periphery of the blade 26 to cover the inner layer 24 and the blade 26. The resin material forming the middle layer 29 is not particularly limited, and polyamide, polyamide elastomer, polyester, polyurethane, or the like is used.

  As shown in the cross-sectional view of FIG. 3, the middle layer 29 includes the main body portion 10a of the catheter shaft 10 excluding the distal end tip 12, the distal end portion 10b adjacent to the main body portion 10a, and the most distal end portion adjacent to the distal end portion 10b. 10c, and is bonded to the inner layer 24 in the gap between the blades 26 (in other words, the region where the first strand 26a and the second strand 26b do not overlap).

Moreover, since the convex part 31 is formed in the outer surface of the middle layer 29 in the position where the blade 26 exists, and the concave part 32 is formed in the gap | interval of the blade 26, the middle layer 29 has an uneven | corrugated shaped outline, respectively. .

An outer layer 28 made of resin is formed on the outer periphery of the middle layer 29 to cover the middle layer 29. The resin material forming the outer layer 28 is not particularly limited, and polyamide, polyamide elastomer, polyester, polyurethane and the like are used as in the case of the middle layer 29. The outer layer 28 is configured using resin materials having different hardnesses so that the outer layer 28 becomes flexible from the main body 10a of the catheter shaft 10 toward the most distal portion 10c. Therefore, the first outer layer 28a covering the main body 10a is formed of a highly rigid resin, and the second outer layer 28b covering the tip 10b is formed of a softer resin than the first outer layer 28a. The third outer layer 28c covering 10c is formed of a softer resin than the second outer layer 28b. Further, the first outer layer 28 a, the second outer layer 28 b, and the third outer layer 28 c are bonded to the middle layer 29 in a state of entering the recess 32 of the middle layer 29.

  In the cross-sectional view of FIG. 3, the catheter shaft 10 has a shape having the same inner diameter in the axial direction. However, the shape is not limited to this shape. A shape in which only the most distal end portion 10c of the catheter shaft 10 is reduced in diameter may be formed by increasing the diameter in a tapered shape toward the portion 10a.

  A distal tip 12 made of resin is attached to the distal end of the catheter shaft 10. The tip 12 is a cylindrical member having a tip opening 15. The resin forming the tip 12 is not particularly limited, but is made of polyurethane, polyurethane elastomer or the like. Further, the tip 12 may contain a heavy metal powder having radiopacity. For example, the tip 12 contains a heavy metal powder (for example, tungsten powder) having radiopacity in a range of about 65 w% to about 90 w%, so that a doctor or the like can accurately position the catheter 1 at the time of examination or treatment. Can grasp.

Next, a state in which the catheter 1 of the present embodiment is inserted into a meandering blood vessel and curved will be described.

As shown in FIG. 4A, when no external force is applied to the catheter 1 and the catheter 1 is not curved, the blades 26 are knitted at an equal pitch L1. When the catheter 1 is bent, the blade 26 located on the main body portion 10a of the catheter shaft 10 tends to move in the rear end direction (right side in the drawing), while the blade 26 located on the distal end portion 10b of the catheter shaft 10. Tries to move in the tip direction (left side in the drawing). Therefore, if the blade 26 is not restrained by the middle layer 29, the first outer layer 28a, and the second outer layer 28b, the pitch interval outside the blade 26 increases from L1 to L3 as shown in FIG. On the other hand, the pitch interval inside the blade 26 is narrowed from L1 to L0. As a result, for example, due to the movement of the blade 26 whose pitch interval increases from L1 to L3, a tensile stress 40a toward the rear end side and a tensile stress 40b toward the front end side are generated in the middle layer 29 (see FIG. 4 (B)).

In the catheter 1 of the present embodiment, since the thickness of the middle layer 29 is constant from the main body portion 10a to the most distal portion 10c, the adhesive strength (adhesion) between the middle layer 29 and the inner layer 24 is the main body of the catheter shaft 10. It is uniform from the portion 10a to the most advanced portion 10c. Therefore, the movement suppression of the blade 26 by the middle layer 29 is approximately the same in the main body portion 10a and the tip portion 10b. Since the tensile stress 40a to the rear end side and the tensile stress 40b to the front end side are balanced, and the spread of the pitch interval of the blade 26 can be suppressed to L2 instead of L3, the main body 10a and the front end 10b Concentration of stress at the boundary can be reduced. The relationship between the pitch intervals is L0 <L1 <L2 <L3.

As shown in FIG. 4B, in the catheter 1 of the present embodiment, the middle layer 29 is formed of a resin having higher rigidity (in other words, having a certain degree of rigidity) than the second outer layer 28b. Even when the blade 26 is moved by the bending when the catheter 1 is bent, the middle layer 29 has a certain degree of rigidity, so that the movement of the blade 26 can be suppressed and the pitch interval can be reduced to L2. . By using the middle layer 29 having a certain degree of rigidity, it becomes possible to adjust the movement of the blade 26 that could not be suppressed by the flexible second outer layer 28b.

Further, as the blade 26 moves, the convex portion 31 of the intermediate layer 29 partially moves into the adjacent concave portion 32. For example, if the convex portions 31 in the middle layer 29 that are near the boundary between the main body portion 10a and the distal end portion 10b are 31a and 31b, respectively, when the catheter 1 is bent, the convex portions 31a and the convex portions The middle layer 29 with 31b moves to the concave portion 32 between the convex portions 31a and 31b while extending in the axial direction. Therefore, as the blade 26 moves, the middle layer 29 can extend in the axial direction. Thereby, the middle layer 29 can relieve the tensile stress 40a, 40b by the blade 26, and the concentration of stress generated at the boundary between the first outer layer 28a and the second outer layer 28b can be reduced.

Further, when the catheter 1 is bent, a tensile stress 30a toward the rear end acts on the first outer layer 28a of the main body 10a, and a tensile stress 30b toward the distal end acts on the second outer layer 28b of the distal end 10b. Even in this case, since the first outer layer 28a and the second outer layer 28b enter the concave portion 32 of the middle layer 29 and adhere to each other, the first outer layer 28a and the second outer layer 28b are hardly separated from the middle layer 29 due to the anchor effect. can do.

In this way, even when the catheter 1 is placed in a curved state for a long time, the blade is formed by the middle layer 29 having a certain thickness and an uneven contour from the main body portion 10a to the distal end portion 10b. 26 can be suppressed, and the first outer layer 28 a and the second outer layer 28 b can be made difficult to peel from the middle layer 29.

As shown in FIGS. 5A and 5B, as the catheter 1 of another embodiment, the middle layer 29 may be formed of a resin having higher rigidity than the first outer layer 28a and the second outer layer 28b. 4A and 4B will be described only. When the catheter 1 is bent by using the middle layer 29 having higher rigidity than the first outer layer 28a and the second outer layer 28b, the blade by bending is used. The movement of the blade 26 (for example, the pitch interval of the blade 26 is increased) can be further suppressed, and the tensile stresses 40a and 40b by the blade 26 can be prevented from being generated. However, when a resin having high rigidity is used for the middle layer 29, the rigidity from the main body portion 10a to the most distal portion 10c of the catheter shaft 10 is increased. Therefore, it is preferable to make the thickness of the middle layer 29 as thin as possible.

As shown in FIGS. 3 to 5B, the cross-sectional shape of the second strand 26b constituting the blade 26 is round, and the cross-sectional shape of the first strand 26a is longer than the diameter of the round shape. It has a rectangular shape. When a high tension metal is used for the material of the first strand 26a and the second strand 26b, the braided blade 26 itself tends to spread in the circumferential direction (direction perpendicular to the axial direction). When the blade 26 is curved, a stress is generated in the circumferential direction to try to separate the middle layer 29 from the inner layer 24. Therefore, by inserting a part of the middle layer 29 between the rectangular first strand 26a and the round second strand 26b, the catheter 1 is curved due to the anchor effect, and thus in the circumferential direction. Even when a stress is generated, it is possible to reduce the peeling of the intermediate layer 29 from the inner layer 24.

In addition, although not shown in figure, the cross-sectional shape of the 1st strand 26a and the 2nd strand 26b which comprises the braid | blade 26 can also be made into a rectangle. As a result, the contact area between the first strand 26a and the second strand 26b can be increased to increase the frictional resistance, and the movement of the blade 26 due to bending (in other words, the pitch interval of the blade 26 increases) can be suppressed. Thus, the tensile stresses 40a and 40b caused by the blade 26 can be reduced.

As shown in FIGS. 3 to 5B, the boundary between the main body portion 10a and the tip portion 10b (the boundary between the first outer layer 28a and the second outer layer 28b) is disposed in the concave portion 32 of the middle layer 29. ing. As a result, when the catheter 1 is bent, the rear end of the second outer layer 28b (the second outer layer 28b near the boundary) is caught by the convex portion 31b of the middle layer 29, and the second outer layer 28b is further moved by the anchor effect. It can be made difficult to peel from the middle layer 29. For the same reason, the boundary between the distal end portion 10 b and the most distal end portion 10 c (the boundary between the second outer layer 28 b and the third outer layer 28 c) is disposed in the concave portion 32 of the middle layer 29.

Next, the process of producing the catheter 1 of the present embodiment will be described with reference to FIG.

First, the inner layer 24 is formed on the cored bar 22. Next, the first strand 26 a and the second strand 26 b are knitted on the outer periphery of the inner layer 24 to form the blade 26. Thereafter, the middle layer 29a and the first rigid outer layer 28a having high rigidity are inserted into the outer periphery of the blade 26, and the middle layer 29b having the same rigidity as the middle layer 29a and the second outer layer 28b that is more flexible than the first outer layer 28a are inserted, The middle layer 29c having the same rigidity as the middle layer 29a and the second outer layer 28c that is more flexible than the first outer layer 28b are sequentially inserted. Then, the inner layer 24, the middle layer 29, and the outer layer 28 (the first outer layer 28a, the second outer layer 28b, and the third outer layer 28c) are welded by heating at a predetermined temperature. At this time, since the middle layers 29a, 29b, and 29c are made of the same material, it is possible to form the middle layer 29 that covers the blade 26 from the main body portion 10a to the most distal end portion 10c of the catheter shaft 10.

The tip of the blade 26 is covered with a tube made of a resin that becomes the tip of the tip 12 and heated and welded at a predetermined temperature, whereby the tip of the tip 12 is formed on the catheter shaft 10. Thereafter, by extracting the cored bar 22, the catheter 1 having the catheter shaft 10 and the tip 12 can be produced.

In the above description, attention has been paid to the boundary between the main body portion 10a of the catheter shaft 10 and the distal end portion 10b which is an adjacent portion adjacent to the main body portion 10a, but the distal end portion 10b and the distal end portion 10b of the catheter shaft 10 are adjacent to each other. The same applies to the boundary with the most advanced part 10c, which is an adjacent part. The same applies to the case where the main body portion 10a and the distal end portion 10b of the catheter shaft 10 are combined and regarded as the main body portion, and the most advanced portion 10c adjacent to the main body portion is regarded as the distal end portion. That is, the present invention can be applied anywhere as long as the boundary is between the outer layers having different hardnesses.

In the above description, the middle layer 29 coats the blade 26 over the entire length from the rear end to the front end of the catheter shaft 10, but the shape is not limited to this. Since the middle layer 29 having a certain thickness and having an uneven contour should be provided in the vicinity of the boundary between the outer layers having different hardnesses, the leading end or the rear end of the blade 26 is coated on the middle layer 29. Even if not, the above-described effects of the present invention can be obtained.

Further, in the above description, three types of outer layers having different hardness (first outer layer 28a, second outer layer 28b, and third outer layer 28c) are used for the catheter shaft 10, but the number of types is not particularly limited. What is necessary is just to increase / decrease the number of the outer layers to be used as needed.

As described above, in the catheter 1 of the present embodiment, since the thickness of the middle layer 29 is constant from the main body portion 10a to the distal end portion 10b, the adhesive strength (adhesion) between the middle layer 29 and the inner layer 24 is high. The catheter shaft 10 is uniform from the main body portion 10a to the distal end portion 10b. Therefore, when the catheter 1 is bent, the movement of the blade 26 due to the bending (in other words, the pitch interval between the blades 26 is increased) can be uniformly suppressed from the main body portion 10a to the distal end portion 10b. Further, when the catheter 1 is bent, a tensile stress 30a toward the rear end acts on the first outer layer 28a of the main body 10a, and a tensile stress 30b toward the distal end acts on the second outer layer 28b of the distal end 10b. Even in this case, it is possible to prevent the first outer layer 28a and the second outer layer 28b from being peeled off from the middle layer 29 due to the anchor effect.

DESCRIPTION OF SYMBOLS 1 Catheter 10 Catheter shaft 12 Tip 14 Connector 15 Tip opening 18 Lumen 24, 240 Inner layer 26, 260 Blade 26a, 26b Wire 28, 280 Outer layer 29 Middle layer 30a, 30b Tensile stress 31 Convex part 32 Concave part 40a, 40b Tensile stress

Claims (4)

The inner layer,
A blade knitted on the outer periphery of the inner layer;
An intermediate layer covering the outer periphery of the blade;
A first outer layer made of a resin covering the outer periphery of the middle layer;
In the catheter provided with a second outer layer made of a resin more flexible than the first outer layer, covering the outer periphery of the middle layer on the distal end side than the first outer layer,
The intermediate layer has a contour including a convex portion on the blade, and a concave portion in a gap with the adjacent blade,
A catheter, wherein a boundary between the first outer layer and the second outer layer is disposed in the concave portion of the middle layer. A third outer layer made of a resin more flexible than the second outer layer, covering the outer periphery of the middle layer on the tip side of the second outer layer;
The catheter according to claim 1, wherein a boundary between the second outer layer and the third outer layer is disposed in the concave portion of the middle layer. The catheter according to claim 1 or 2, wherein the middle layer is made of a resin having higher rigidity than the second outer layer. The catheter according to claim 3, wherein the middle layer is made of a resin having higher rigidity than the first outer layer.