Guide extension catheter

Abstract

To provide a new guide extension catheter capable of being inserted into a further distal position of the coronary artery.SOLUTION: A guide extension catheter 10 including a distal shaft 12 and a proximal shaft 14 is such that: a maximum load value acting on a body part 16 is 0.1 N or more and 0.6 N or less when mounting the body part 16 of the distal shaft 12 on a support base 30 of a three-point bending test jig where a distance between fulcrums 32, 32 is 15 mm, pressing from the lateral side a depressor 34 approaching the support base 30 at a speed of 10 mm / min in the center between the fulcrums 32, 32 to the body part 16, and deforming the body part 16 so as to generate a kink. An end chip 18 softer than the body part 16 is disposed in the distal shaft 12, and a non-skid part comprising an outer peripheral surface having a friction coefficient larger than that of the end portion is disposed in the base end portion of the distal shaft 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a guide extension catheter used to deliver a treatment catheter to a more distal lesion site, for example, during percutaneous coronary intervention (PCI). [Background technology]

[0002] Conventionally, percutaneous coronary intervention (PCI) using a treatment catheter has been performed as a less invasive treatment method for, for example, coronary artery stenosis or blockage, compared to surgical treatment via thoracotomy. PCI is a procedure in which a treatment catheter is guided to the site of a lesion, such as a stenosis, in a coronary artery using a guiding catheter, and treatment is performed using the treatment catheter delivered to the lesion site distal to the guiding catheter.

[0003] Considering the passability of a guiding catheter through a body lumen up to the entrance of a coronary artery, for example, a guiding catheter is required to have excellent pushability, and therefore is required to have excellent torque transmission efficiency, kink resistance, etc. Therefore, it is difficult to insert a guiding catheter into a coronary artery that is thin and has complex windings, and when an attempt is made to insert a treatment catheter into the coronary artery from the distal opening of a guiding catheter that is arranged so as to be hooked onto the entrance of the coronary artery, the treatment catheter is unable to fully follow the curvature of the coronary artery, and there are cases in which it is impossible to insert the treatment catheter to the vicinity of the distal lesion site.

[0004] Therefore, in order to support the delivery of a treatment catheter to a more distal lesion site, International Publication No. 2018 / 030075 (Patent Document 1) proposes a guide extension catheter to be inserted into a coronary artery. The guide extension catheter is inserted into a guiding catheter and inserted into the coronary artery from the distal end of the guiding catheter. The guide extension catheter has a smaller diameter than the guiding catheter because it is inserted into the coronary artery through the lumen of a guiding catheter that has been inserted into the coronary artery beforehand. The guide extension catheter has better tracking ability in tortuous coronary arteries than the guiding catheter, can reach more distal parts of the coronary artery, and can deliver a treatment catheter to a more distal lesion site. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 030075 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there is a limit to the range to which a guide extension catheter with a conventional structure can be inserted into a coronary artery, etc., and in order to treat a distal lesion in a coronary artery, etc., with a treatment catheter, a guide extension catheter that can be inserted further distally into the coronary artery, etc., may be required.

[0007] An object of the present invention is to provide a novel guide extension catheter that can be inserted further distally into the coronary artery, etc. [Means for solving the problem]

[0008] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0009] In the first aspect, a guide extension catheter has a tubular distal shaft provided at the distal end of a proximal shaft, wherein the main body portion of the distal shaft is placed on a support base of a three-point bending test jig with a distance between fulcrums set to 15 mm, and an indenter moving toward and toward the support base at a relative movement speed of 10 mm / min is pressed against the main body portion from the side at the central portion between the fulcrums of the support base to deform the main body portion until a kink occurs. The maximum load value applied to the main body portion is 0.1 N or more and 0.6 N or less, and a distal tip that is more flexible than the main body portion is provided on the distal shaft distal to the main body portion, and the length of the distal tip is 2.5 mm or more, and the distal tip has a marker portion containing powder made of an X-ray opaque material, and the base end portion of the distal shaft is provided with an anti-slip portion consisting of an outer circumferential surface with a higher friction coefficient than the distal portion.

[0010] With a guide extension catheter constructed according to this aspect, the main body portion of the distal shaft is able to ensure conformability to the curvature of a blood vessel or the like due to bending deformation, while avoiding a decrease in pushability and kink resistance due to excessive flexibility. Therefore, the distal shaft is able to conform highly to the shape of a coronary artery or the like, allowing the distal shaft to be inserted further distally into the coronary artery or the like.

[0011] Furthermore, by providing a distal tip that is more flexible than the main body portion while imparting a certain degree of rigidity to the main body portion, for example, when passing through a sharply curved portion such as a coronary artery, the distal tip, which easily follows the curved shape of the coronary artery, leads the main body portion, making it easier for the tip of the main body portion to face in the extension direction of the coronary artery, etc., and the main body portion to be easily guided in the extension direction of the coronary artery, etc. by the distal tip.

[0012] In order for the distal tip to effectively guide the main body, it is necessary for the distal tip to have a length that allows it to deform into a curved shape that follows the coronary artery, etc. Therefore, by making the length of the distal tip 2.5 mm or more, the flexible distal tip can be curved and deformed, effectively improving the passage of the distal shaft through the coronary artery, etc.

[0013] Conventional guide extension catheters have a ring marker attached to the distal end to ensure visibility of the distal end under X-ray fluoroscopy, but the hard ring marker limits the flexible area of ​​the distal end, which can adversely affect insertion. Therefore, in this embodiment, the marker portion for ensuring visibility under X-ray fluoroscopy is formed from a material containing a powder made of a radiopaque material, thereby providing sufficient flexibility. By providing such a flexible marker portion on the distal tip, it is possible to ensure visibility of the distal shaft's distal end under X-ray fluoroscopy while preventing the effective length of the distal tip from being shortened by the attachment of a hard marker, thereby achieving excellent followability of the distal shaft to blood vessels, etc.

[0014] The length of the distal tip varies depending on the flexibility of the material of the distal tip, but is preferably 10 mm or less, for example. If the flexible distal tip is too long, the distal portion of the distal shaft formed by the distal tip is likely to deform, which may cause the lumen of the distal shaft to collapse and become blocked, or increase resistance when inserting it into a blood vessel. Furthermore, by providing an anti-slip portion at the base end portion of the distal shaft that should remain within the guiding catheter, the distal shaft can be more easily positioned relative to the guiding catheter, preventing problems such as the entire distal shaft accidentally becoming exposed from the guiding catheter.

[0015] In the second aspect, in the guide extension catheter described in the first aspect, a coating layer made of a hydrophilic polymer is provided on the outer surface of the distal shaft in a length region extending from the tip to the base end of the distal shaft but not reaching the base end.

[0016] With a guide extension catheter constructed according to this aspect, the lubricity of the outer peripheral surface of the distal shaft is improved, facilitating insertion when inserting the distal shaft into a guiding catheter, a coronary artery, etc. Furthermore, because the coating layer is provided in a length region that does not reach the proximal end of the distal shaft, which is to remain within the guiding catheter, the coating layer is prevented from making it difficult to position the distal shaft relative to the guiding catheter, and problems such as the distal shaft becoming dislodged from the guiding catheter can be prevented.

[0017] In a third aspect, in the guide extension catheter described in the first or second aspect, the main body portion of the distal shaft is wound around a kink test jig having a cylindrical outer surface, and the outer diameter of the kink test jig, which causes kinking when wound around the kink test jig, is 3 mm or less.

[0018] With a guide extension catheter constructed according to this aspect, the main body portion of the distal shaft is less likely to kink, which reduces the likelihood of reduced pushability due to kinking, poor insertion of the treatment catheter, etc. Furthermore, because the main body portion of the distal shaft can be bent to a smaller radius of curvature without kinking, it exhibits excellent follow-up ability around tortuous coronary arteries, etc.

[0019] In the fourth aspect, in the guide extension catheter described in any one of the first to third aspects, the main body portion of the distal shaft has a maximum load value of 4.0 N or more when the main body portion is radially sandwiched between the support surface and the crushing jig and a load of 0.5 N is applied, and then the crushing jig is further pushed 0.5 mm in the direction approaching the support surface.

[0020] With a guide extension catheter constructed according to this aspect, the main body portion of the flexible distal shaft achieves excellent bending flexibility, which is thought to contribute to its ability to follow the coronary arteries, etc., while ensuring resistance to radial collapse, thereby maintaining a stable cross-sectional shape. Therefore, it is possible to prevent the distal shaft from deforming into an elliptical cross section, which would otherwise increase the contact area with the coronary arteries, etc., and reduce resistance during insertion.

[0021] The fifth aspect is a guide extension catheter described in any one of the first to fourth aspects, wherein the distal tip has a maximum load value of 0.5 N or more and 1.5 N or less when the distal shaft connected to the distal tip at a position 5 mm from the tip toward the base end is restrained by a holding jig and the distal surface of the distal tip is abutted against a pressing jig, and the holding jig is then moved toward the pressing jig at a pushing speed of 10 mm / min to compress the distal tip by 1 mm in the longitudinal direction.

[0022] According to the guide extension catheter constructed in accordance with this embodiment, the distal tip is sufficiently soft while maintaining the hardness (rigidity) required for insertion into the coronary artery, etc., thereby more advantageously ensuring the guide extension catheter's ability to follow the coronary artery, etc. [Effects of the Invention]

[0023] According to the present invention, it becomes possible to insert a guide extension catheter to a more distal position, such as into a coronary artery. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a side view showing a guide extension catheter according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a main part of the guide extension catheter of FIG. [Figure 3] FIG. 2 shows a three-point bending test of the main body of the distal shaft constituting the guide extension catheter of FIG. 1. [Figure 4] Figure 2 shows a flexibility test of the distal end of the distal shaft that constitutes the guide extension catheter of Figure 1. [Figure 5] Figure 2 shows a kink resistance test of the distal shaft that constitutes the guide extension catheter of Figure 1. [Figure 6] FIG. 2 shows a crushing test of the distal shaft constituting the guide extension catheter of FIG. 1. [Figure 7] FIG. 2 is a side view of a catheter assembly including the guide extension catheter of FIG. 1. [Figure 8] FIG. 8 is a diagram showing the catheter assembly of FIG. 7 in use. [Figure 9] Photograph showing the test equipment used to test the tracking ability of the guide extension catheter [Figure 10A] Photographs showing the results of a tracking test in which the guide extension catheters of Examples 1 to 6 were inserted into the left anterior descending artery using the test device shown in FIG. [Figure 10B]Photographs showing the results of a tracking test in which the guide extension catheters of Comparative Examples 1 to 6 were inserted into the left anterior descending artery using the test device shown in FIG. [Figure 11A] Photographs showing the results of a tracking test in which the guide extension catheters of Examples 1 to 6 were inserted into the left circumflex artery using the test device shown in FIG. [Figure 11B] Photographs showing the results of a tracking test in which the guide extension catheters of Comparative Examples 1 to 6 were inserted into the left circumflex artery using the test device shown in FIG. [Figure 12A] Photographs showing the results of a tracking test in which the guide extension catheters of Examples 1 to 6 were inserted into the right coronary artery R1 of the test device shown in FIG. [Figure 12B] Photographs showing the results of a tracking test in which the guide extension catheters of Comparative Examples 1 to 6 were inserted into the right coronary artery R1 of the test device shown in FIG. [Figure 13A] Photographs showing the results of a tracking test in which the guide extension catheters of Examples 1 to 6 were inserted into the right coronary artery R2 of the test device shown in FIG. [Figure 13B] Photographs showing the results of a tracking test in which the guide extension catheters of Comparative Examples 1 to 6 were inserted into the right coronary artery R2 of the test device shown in FIG. [Figure 14] Graph showing the results of a three-point bending test on the main body of the distal shaft [Figure 15] Graph showing the measurement results of the distal tip length of the distal shaft [Figure 16] Graph showing the flexibility test results for the distal shaft tip [Figure 17] Graph showing the results of kink resistance tests on distal shafts [Figure 18] Graph showing distal shaft collapse test results DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0026] 1 shows a guide extension catheter 10 used for coronary artery treatment as a first embodiment of the present invention. The guide extension catheter 10 is a rapid exchange type catheter and includes a distal shaft 12 and a proximal shaft 14.

[0027] The distal shaft 12 is a generally cylindrical tube made of, for example, a soft synthetic resin, etc. The distal shaft 12 includes a main body portion 16 and a distal tip 18 provided distally of the main body portion 16.

[0028] The main body portion 16 of the distal shaft 12 is a so-called braided tube, and as shown in FIG. 2 , has a structure in which a metallic braided body 24 is disposed between an inner layer 20 and an outer layer 22 formed of synthetic resin or the like. The inner layer 20 and the outer layer 22 are fixed to each other by, for example, adhesion or welding, or are integrally molded, thereby providing an embedded braided body 24. When the main body portion 16 has a three-layer structure consisting of the inner layer 20, the outer layer 22, and the braided body 24, the inner layer 20 and the outer layer 22 may be formed of different materials or the same material. The inner layer 20 and the outer layer 22 are formed of, for example, a fluorine-based, polyamide-based, polyester-based, or urethane-based synthetic resin. The three-layer structure of the main body portion 16 provides flexibility in the bending direction and improves load transmission efficiency in the axial direction, achieving both good conformability to bending and pushability during insertion.

[0029] The distal tip 18 constituting the distal portion 26 of the distal shaft 12 is softer than the main body portion 16 and is more easily deformed when a load is applied. The distal tip 18 may be formed from a different material than the main body portion 16, but it can also be formed from the same material as the inner layer 20 and outer layer 22 of the main body portion 16. For example, the distal tip 18 is made more flexible than the main body portion 16 due to the absence of the braid 24 or the difference in the forming material.

[0030] The distal tip 18 includes a marker portion formed of a material obtained by mixing a powder of a radiopaque material into a resin. In this embodiment, the entire distal tip 18 is formed of a material mixed with the radiopaque powder, and the entire distal tip 18 serves as the marker portion. However, the entire distal tip 18 does not have to be the marker portion; for example, a marker portion can be provided partially on the distal tip 18. For example, only one of the distal end and the proximal end of the distal tip 18 may be the marker portion, or a marker portion can be provided midway along the distal tip 18. The radiopaque powder used in the marker portion is not particularly limited as long as it has low X-ray transmittance and does not pose a problem of adverse effects on the human body. For example, metal powder such as bismuth oxide or tungsten, which has excellent visibility under X-ray fluoroscopy, is preferably used. The marker portion is preferably softer than the main body portion 16 of the distal shaft 12, but may be harder than the main body portion 16, for example, if the marker portion is provided on part of the distal tip 18.

[0031] The length of the distal tip 18 in the axial direction is 2.5 mm or more. The length of the distal tip 18 is desirably 10 mm or less. More preferably, the length of the distal tip 18 is 3 mm or more and 7 mm or less, and in this embodiment, it is about 4 mm.

[0032] The distal shaft 12 includes a coating layer 28. The coating layer 28 is formed from a hydrophilic polymer, such as polyvinylpyrrolidone (PVP), vinyl methyl ether-maleic anhydride copolymer (VEMA), or an acrylic or hyaluronic acid coating material. The coating layer 28 covers the distal end of the distal tip 18 and the outer circumferential surface of the main body 16, distal to the connecting tube 48 (described later). The coating layer 28 extends from the distal end of the distal shaft 12 to the proximal end of the distal shaft 12, but does not extend all the way to the proximal end. The coating layer 28 is preferably provided over a length of at least half of the total length of the distal shaft 12, and in this embodiment, over approximately two-thirds of the total length. The coating layer 28 may also cover substantially the entire outer circumferential surface of the distal shaft 12, from the distal end of the distal tip 18 to the proximal end of the main body 16. In this case, for example, the coating layer 28 at the base end of the main body portion 16 is covered with a connecting tube 48 described below, so that the coating layer 28 is not exposed on the outer peripheral surface at the base end of the main body portion 16.

[0033] In a three-point bending test, the maximum load applied to the main body 16 of the distal shaft 12 when deformed until a kink occurs is 0.6 N or less. By setting the bending characteristics of the main body 16 as described above, the main body 16 is allowed to undergo large lateral deflections before a kink occurs, and has excellent flexibility that allows the main body 16 to undergo lateral bending deformation even when a relatively small load is applied.

[0034] Furthermore, the maximum load value acting on the main body portion 16 of the distal shaft 12 when deformed to the point of kinking in a three-point bending test is set to 0.1 N or more, more preferably 0.3 N or more. This achieves the main body portion 16 of the distal shaft 12 that combines flexibility with a certain degree of shape stability, and when the guide extension catheter 10 is pushed toward the distal end, the main body portion 16 does not unnecessarily deform, and the operating force is efficiently transmitted to the distal end.

[0035] The three-point bending test can be performed as follows. As shown in FIG. 3, the tester first places the main body portion 16 of the distal shaft 12 on the support base 30 of the test jig, with the distance between the supports 32 set at 15 mm. Next, an indenter 34, which moves toward the support base 30 at a relative movement speed of 10 mm / min, presses against the main body portion 16 from the side (upper side in FIG. 3) to deform the main body portion 16 until a kink occurs. The maximum load acting on the main body portion 16 when a kink occurs is then measured. The main body portion 16 of the distal shaft 12 used in the three-point bending test had a length of 50 mm.

[0036] The maximum load value acting on the main body portion 16 of the distal shaft 12 measured by the above three-point bending test is desirably greater than the maximum load value acting on the distal tip 18 measured by the same three-point bending test. In this way, the main body portion 16 of the distal shaft 12 has greater bending rigidity than the distal tip 18, preventing a decrease in the efficiency of transmission of the operating force due to excessive deformation of the main body portion 16 when an operating force is applied to push the guide extension catheter 10 toward the distal side. Furthermore, when the distal tip 18 is butted against an object, the distal tip 18, which is more flexible than the main body portion 16 of the distal shaft 12, deforms first in preference to the main body portion 16, making it easier for the distal tip 18 to face in the extension direction of the coronary artery 66 (described below).

[0037] The distal shaft 12 has a maximum load value of 0.5 N or more and 1.5 N or less, as measured in a flexibility test of the tip portion 26. By setting the flexibility of the tip portion 26 as described above, the tip portion 26 is made flexibly deformable while maintaining a certain degree of shape stability against impact in the axial direction.

[0038] The flexibility test for the distal portion 26 can be performed as follows. As shown in Figure 4, the tester first uses a holding jig 36 to restrain the distal shaft 12 from its distal tip to the proximal end, extending 5 mm from the distal end, so that it cannot be deformed. The tester then places the distal end surface of the distal tip 18, which is the distal end surface of the distal shaft 12, in contact with a pressing jig 38. The holding jig 36 is formed, for example, by combining a cylindrical outer tube that restrains the outer peripheral surface of the distal shaft 12 with a columnar inner shaft that restrains the inner peripheral surface of the distal shaft 12. Next, the holding jig 36 is moved toward the pressing jig 38 at a speed of 10 mm / min, compressing the distal portion (distal tip 18) of the distal shaft 12 exposed from the holding jig 36 by 1 mm in the longitudinal direction, and measuring the maximum load value at this time.

[0039] In a kink resistance test in which the main body portion 16 of the distal shaft 12 is wound around a kink test jig 40 having a cylindrical outer circumferential surface as shown in Figure 5, kinking may occur when the main body portion 16 is bent with a small radius of curvature of 3 mm or less. In other words, the main body portion 16 has excellent kink resistance, making it unlikely for kinking to occur when bending with a radius of curvature exceeding 3 mm. By setting the kink resistance of the main body portion 16 as described above, the main body portion 16 can tolerate bending with a small radius of curvature without kinking, and poor force transmission due to kinking is unlikely to occur.

[0040] The kink resistance test involves preparing a kink test jig 40 having an outer peripheral surface with different outer diameter dimensions, bending and deforming the main body portion 16 along the outer peripheral surface of the kink test jig 40, and checking whether kinking occurs in the main body portion 16. The tester then gradually decreases the outer diameter of the kink test jig 40 along which the main body portion 16 is fitted, and the outer diameter of the kink test jig 40 when a kink occurs in the main body portion 16 is taken as the test result. Therefore, the smaller the outer diameter of the kink test jig 40, which is the test result of the kink resistance test, the less likely kinking due to bending deformation will occur in the main body portion 16, and the more excellent the kink resistance of the main body portion 16.

[0041] It is desirable that the maximum load value measured in a crushing test for the main body portion 16 of the distal shaft 12 be 6.0 N or less. By setting the crushing characteristics of the main body portion 16 as described above, the main body portion 16 is relatively susceptible to crushing deformation (change in cross-sectional shape) due to a lateral load, and is susceptible to bending deformation accompanied by a change in cross-sectional shape, thereby achieving excellent bending flexibility.

[0042] Furthermore, it is desirable that the maximum load value of the main body portion 16 of the distal shaft 12 measured in a crushing test be 4.0 N or greater. This prevents the cross-sectional shape of the main body portion 16 from changing more than necessary in response to an input, making it easier to maintain the lumen of the distal shaft 12. For example, by setting the maximum load value measured in a crushing test of the main body portion 16 to 4.0 N or greater and 6.0 N or less, it is possible to achieve both excellent flexibility against bending of the main body portion 16 and maintenance of the lumen of the main body portion 16.

[0043] The crushing test can be carried out as follows: First, as shown in Figure 6, the tester clamps the main body portion 16 of the distal shaft 12 radially between the support surface 42 and the crushing jig 44 and applies a load of 0.5 N. Next, the crushing jig 44 is moved 0.5 mm toward the support surface 42, and the maximum load value when the main body portion 16 is further crushed radially is measured.

[0044] The proximal shaft 14 is made of a metal wire such as medical stainless steel. A plate-shaped protective member 46 is provided on the proximal end side of the proximal shaft 14 to prevent the practitioner or the like from coming into contact with the proximal end of the proximal shaft 14. The outer peripheral surface of the proximal shaft 14 may be coated to improve lubricity and corrosion resistance.

[0045] The distal end portion of the proximal shaft 14 is superimposed on the outer peripheral surface of the main body portion 16 of the distal shaft 12 and is connected to the main body portion 16 by a connecting tube 48 that is fixedly attached in an externally fitted state to the main body portion 16. The connecting tube 48 is formed of a synthetic resin or the like, and is, for example, contracted and deformed by heating or other means while the distal end portion of the proximal shaft 14 is externally fitted onto the proximal end portion of the main body portion 16. As a result, the connecting tube 48 is tightly fixed to the proximal end portion of the main body portion 16 of the distal shaft 12 and the distal end portion of the proximal shaft 14. By providing the connecting tube 48 in this manner, the proximal end portion of the main body portion 16 of the distal shaft 12 and the distal end portion of the proximal shaft 14 are fixed to each other by the connecting tube 48, and the distal end portion of the proximal shaft 14 is connected to the proximal end portion of the distal shaft 12. In this embodiment, the outer layer 22 and braid 24 of the main body portion 16 do not reach the proximal end of the distal shaft 12, and the proximal end of the distal shaft 12 is formed by the inner layer 20 and the connecting tube 48. However, at least one of the outer layer 22 and the braid 24 may reach the proximal end of the distal shaft 12, or the inner layer 20 may not reach the proximal end of the distal shaft 12.

[0046] The above-described connection structure between the proximal shaft 14 and the distal shaft 12 is merely an example and is not particularly limited. Specifically, for example, the distal portion of the proximal shaft 14 may be fixed to the distal shaft 12 by being disposed and fixed between the inner layer 20 and the outer layer 22 over a predetermined length on the proximal side of the distal shaft 12, in which case the connecting tube 48 may be omitted. When the proximal shaft 14 is fixed between the inner layer 20 and the outer layer 22, it is desirable that the inner layer 20 and the outer layer 22 form the proximal end of the distal shaft 12, and the braid 24 does not have to reach the proximal end of the distal shaft 12.

[0047] Furthermore, by disposing the connecting tube 48 at the proximal end portion of the distal shaft 12, an anti-slip portion without a coating layer 28 on its outer circumferential surface is provided by the connecting tube 48 at the proximal end portion of the distal shaft 12. The coating layer 28 provided distally of the connecting tube 48 is disposed on the outer circumferential surface of the distal shaft 12 in a length region extending from the distal end toward the proximal end of the distal shaft 12, not reaching the proximal end. The anti-slip portion has a higher coefficient of friction in blood against the blood vessel wall and the guiding catheter 50 (described later), compared to portions where the coating layer 28 reduces the coefficient of friction against these elements. Furthermore, by providing the anti-slip portion (connecting tube 48) on the outer circumferential surface of the proximal end portion of the distal shaft 12, slippage of the guide extension catheter 10 from the guiding catheter 50 (described later) toward the distal side is prevented.

[0048] The guide extension catheter 10 having such a structure is used by being inserted into a guiding catheter 50, as shown in Figure 7. Any conventionally known guiding catheter 50 can be used as appropriate. The guiding catheter 50 has a bendable, cylindrical catheter main body 52. ​​The catheter main body 52 is a synthetic resin tube with a metal reinforcing material (braided body) embedded therein, similar to the main body portion 16 of the guide extension catheter 10. In addition, a contrast marker 54 that has been made radiopaque by blending a contrast agent or the like is provided at the tip of the catheter main body 52.

[0049] A Y connector 56 is provided at the proximal end of the catheter main body 52. ​​A check valve (not shown) is provided within the Y connector 56 to prevent backflow of blood. The Y connector 56 also has a side arm 58 branching off from the main body, through which medicinal solutions, contrast agents, etc. can be injected.

[0050] A balloon catheter 60 serving as a treatment catheter is inserted into the guide extension catheter 10. The balloon catheter 60 may have a conventionally known structure, and is inserted into a stenotic portion 68 of a coronary artery 66 (described later) and has a balloon 62 provided at its tip end inflated to expand the stenotic portion 68 with the balloon 62. The treatment catheter is not limited to the balloon catheter 60 that expands the stenotic portion 68 with the balloon 62. Specifically, various known treatment catheters may be used, such as a cutting balloon catheter provided with a cutting balloon having blades on its outer circumferential surface, a stent delivery catheter that places a stent in the stenotic portion 68, an atherectomy catheter or a rotator that removes a stenotic lesion to eliminate the stenosis, etc.

[0051] The catheter assembly 64 includes the guiding catheter 50, the guide extension catheter 10, and the balloon catheter 60. In the catheter assembly 64, the guide extension catheter 10 is inserted into the guiding catheter 50, and the balloon catheter 60 is inserted into the guide extension catheter 10.

[0052] Such a catheter assembly 64 is used, for example, when dilating a stenosis 68 in a coronary artery 66 of the heart by percutaneous transluminal coronary angioplasty (PTCA). For reference, an example of using the catheter assembly 64 in a procedure using a transfemoral approach will be briefly described below.

[0053] First, the practitioner punctures the patient's femoral artery 70 with a needle (not shown), and inserts a sheath 72 into the femoral artery 70 from the puncture site, as shown in Fig. 8. The practitioner then inserts the guiding catheter 50, which has been inserted into the femoral artery 70 from the sheath 72, into the ascending aorta 74, and positions the tip of the guiding catheter 50 at the entrance of the coronary artery 66.

[0054] Next, the practitioner inserts the guide extension catheter 10 onto the guide wire 76 inserted into the guiding catheter 50, and pushes the distal portion of the distal shaft 12 of the guide extension catheter 10, which has been advanced inside the guiding catheter 50 along the guide wire 76, so that it protrudes from the distal end of the guiding catheter 50. In this way, the distal shaft 12 is inserted into the coronary artery 66, and the distal end of the distal shaft 12 is positioned just before the stenosis 68 in the coronary artery 66.

[0055] The distal tip 18 constituting the tip of the distal shaft 12 is formed from a resin in which a powder of a radiopaque material such as bismuth oxide or tungsten has been mixed as a contrast agent, and the entire tip serves as a marker portion that can be seen under X-ray fluoroscopy. This allows the practitioner to operate the guide extension catheter 10 while checking the position of the distal tip 18 on a monitor that displays X-ray images, for example, thereby allowing the guide extension catheter 10 inserted into the coronary artery to reach the lesion site. In particular, because the marker portion is flexible, the tip of the distal tip 18 can also be used as a marker portion, making it possible to see the tip of the distal shaft 12 through fluoroscopy, which is not possible with the attachment of a ring marker.

[0056] Thereafter, the practitioner inserts the balloon catheter 60, which is fitted onto the guidewire 76, into the distal shaft 12 of the guide extension catheter 10. Then, the balloon 62 attached to the balloon catheter 60 is protruded distally from the distal shaft 12 and delivered to the stenotic site 68. The balloon 62 inserted into the stenotic site 68 is inflated around the inner circumference of the stenotic site 68, thereby expanding the stenotic site 68 with the balloon 62, thereby restoring blood flow in the coronary artery 66. The guidewire 76 used when inserting the balloon catheter 60 may be different from the guidewire used when inserting the guide extension catheter 10. For example, after completing the insertion of the guide extension catheter 10 into the guiding catheter 50, a thinner guidewire 76 may be inserted and the balloon catheter 60 may be inserted into the guide extension catheter 10.

[0057] The proximal end portion of the distal shaft 12 located within the guiding catheter 50 is provided with an anti-slip portion on its outer circumferential surface using the connecting tube 48. This increases the frictional resistance acting between the proximal end portion of the guide extension catheter 10 and the guiding catheter 50, and positions the guide extension catheter 10 relative to the guiding catheter 50. Therefore, for example, it is possible to prevent the guide extension catheter 10 from slipping out toward the distal end from the guiding catheter 50. Furthermore, for example, when the balloon catheter 60 protruding toward the distal end from the guide extension catheter 10 comes into contact with a stenotic lesion or the like in a blood vessel and applies a force toward the proximal end, it is possible to prevent the guide extension catheter 10 from being pushed back into the guiding catheter 50 by the contact reaction force of the balloon catheter 60. Note that the entire connecting tube 48 constituting the anti-slip portion does not necessarily have to be located within the guiding catheter 50; for example, the tip portion may protrude distally from the guiding catheter 50.

[0058] Although an example of using the catheter assembly 64 in a procedure via a transfemoral approach has been described above, the catheter assembly 64 can also be used in procedures via a transradial approach or a transbrachial approach, for example. Furthermore, while FIG. 8 illustrates a procedure for treating a stenosis 68 in the anterior descending branch of the left coronary artery 66L, the catheter assembly 64 can also be used in procedures for treating a lesion in the circumflex branch of the left coronary artery 66L or in the right coronary artery 66R, for example. Furthermore, the method of using the guide extension catheter 10, including the procedure steps (such as the order of insertion and removal of each catheter and guidewire) illustrated as an example, is merely an example and is not particularly limited. Note that, for ease of viewing, the vascular system in FIG. 8 is shown schematically, with the descending aorta positioned so as not to overlap with the coronary artery 66.

[0059] The guide extension catheter 10 protrudes from the tip of the guiding catheter 50 placed at the entrance of the coronary artery 66, and is inserted into the coronary artery 66 up to just before the stenosis 68, thereby guiding a treatment catheter such as a balloon catheter 60 to the stenosis 68. Therefore, in order to be able to treat the stenosis 68 even when it is far from the entrance of the coronary artery 66, a guide extension catheter 10 that can reach a more distal part of the coronary artery 66 is required. Therefore, the guide extension catheter 10 constructed according to the present invention can be inserted more distally into the coronary artery 66 than guide extension catheters of conventional construction.

[0060] That is, the guide extension catheter 10 has a maximum load value measured by the above-mentioned three-point bending test of 0.1 N or more and 0.6 N or less, the length of the distal tip 18 is 2.5 mm or more, and furthermore, the distal tip 18 is provided with a flexible marker portion containing radiopaque powder, so that a hard ring-shaped marker is not provided. As a result, the guide extension catheter 10 achieves excellent passability, allowing it to be inserted further distally into the coronary artery 66.

[0061] This is evident from the results of a test on the followability of a guide extension catheter to a simulated coronary artery 66. That is, as shown in Figure 9, a test device was prepared in which a cavity corresponding to a blood vessel such as the coronary artery 66 was formed, and the guide extension catheter was inserted into the cavity corresponding to the coronary artery 66 at a speed of 500 mm / min to confirm the followability (passability) of the guide extension catheter to the coronary artery 66.

[0062] In the following description, Examples 1 to 6 are guide extension catheters according to the present invention, Comparative Examples 1 to 5 are guide extension catheters of a conventional structure, and Comparative Example 6 is the guide extension catheter of Example 3 to which a hard ring-shaped contrast marker (ring marker) is attached to shorten the effective length of the distal tip. Furthermore, in the following Figures 10 to 13, the guide extension catheters of Examples 1 to 6 are given the same reference numerals as the guide extension catheter 10 of the above-described embodiment, and the guide extension catheters of Comparative Examples 1 to 6 are given the reference numerals of the guide extension catheter 10', distal shaft 12', and main body portion 16'. Note that Examples 1 to 6 are all guide extension catheters 10 according to the present invention, but differ from one another in terms of the materials used and structure, and, for example, in the distribution of bending hardness along the length of the main body portion 16.

[0063] 10 shows the results of a trackability test of the guide extension catheter for the left anterior descending artery of the left coronary artery 66L. The tip positions of the guide extension catheters 10 of Examples 1 to 6, indicated by arrows in FIG. 10A, all reached further distally than the tip positions of the guide extension catheters 10' of Comparative Examples 1 to 4, indicated by arrows in FIG. 10B. Furthermore, in a trackability test for the left anterior descending artery of the left coronary artery 66L, the tip of the guide extension catheter 10' of Comparative Examples 5 and 6 reached approximately the same position as the tip of the guide extension catheters 10 of Examples 1 to 3, demonstrating superior trackability to the other Comparative Examples 1 to 4. However, Examples 4 to 6 also demonstrated superior trackability, being able to reach even more distally than Comparative Examples 5 and 6. Thus, it was confirmed by experiment that the guide extension catheter 10 according to the present invention can reach a more distal position when inserted into the left anterior descending artery of the left coronary artery 66L.

[0064] Figure 11 shows the results of a test of the trackability of a guide extension catheter in the left circumflex artery of the left coronary artery 66L. The tip positions of the guide extension catheters 10 of Examples 1 to 6, indicated by arrows in Figure 11A, all reached further distally than the guide extension catheters 10' of Comparative Examples 1 to 6, indicated by arrows in Figure 11B. Thus, it was confirmed by experiment that the guide extension catheters 10 of the Examples according to the present invention exhibited significantly superior trackability compared to the comparative examples when inserted into the left circumflex artery of the left coronary artery 66L, and were able to reach further distally.

[0065] FIG. 12 shows the results of a trackability test of the guide extension catheter in the right coronary artery 66R1. The tip positions of the guide extension catheters 10 of Examples 1 to 6, indicated by arrows in FIG. 12A, all reached much further distally than the guide extension catheters 10′ of Comparative Examples 1 to 5, indicated by arrows in FIG. 12B. Furthermore, in the trackability test for the right coronary artery 66R1, the tip of the guide extension catheter 10′ of Comparative Example 6 reached approximately the same position as the tip of the guide extension catheters 10 of Examples 2 and 3, demonstrating superior trackability compared to Comparative Examples 1 to 5. However, Examples 1, 4 to 6 also demonstrated superior trackability, allowing the catheter to reach even more distally than Comparative Example 6. Thus, experiments have confirmed that the guide extension catheter 10 according to the present invention can reach a more distal position when inserted into the right coronary artery 66R1. The proximal portion of the right coronary artery 66R1 is elevated compared to the right coronary artery 66R2, which will be described later.

[0066] FIG. 13 shows the results of a trackability test of a guide extension catheter in the right coronary artery 66R2. The tip positions of the guide extension catheters 10 of Examples 1 to 6, indicated by arrows in FIG. 13A, all reached more distally than the guide extension catheters 10′ of Comparative Examples 1 to 5, indicated by arrows in FIG. 13B. Thus, it was confirmed by experiment that the guide extension catheter 10 according to the present invention can reach more distally when inserted into the right coronary artery 66R2. Note that in the trackability test for the right coronary artery 66R1, the tip of the guide extension catheter 10′ of Comparative Example 6 reached approximately the same position as the tip of the guide extension catheters 10 of Examples 1 and 3, demonstrating superior trackability to the other Comparative Examples 1 to 5. However, Examples 2, 4 to 6 also showed superior trackability, being able to reach even more distally than Comparative Example 6.

[0067] As described above, the guide extension catheters 10 of Examples 1 to 6 according to the present invention have superior tracking ability with respect to the coronary artery 66 compared to the guide extension catheters 10' of Comparative Examples 1 to 6 having a conventional structure, and can be expected to reach more distal parts of the coronary artery 66.

[0068] 14 to 18 show the results of each characteristic test for the guide extension catheter 10 of the example and the guide extension catheter 10' of the comparative example.

[0069] FIG. 14 shows the results of a three-point bending test of the distal shafts of Examples 1 to 6 and Comparative Examples 1 to 6. The results show that the maximum load values ​​of Examples 1 to 6 are all 0.6 N or less, while the maximum load values ​​of Comparative Examples 1 to 5 are all greater than 0.6 N. These test results demonstrate that the main body portion 16 of the distal shaft 12 of Examples 1 to 6 is flexible enough to bend with less force than the main body portion 16' of the distal shaft 12' of Comparative Examples 1 to 5. This suggests that the main body portion 16 of the distal shaft 12 has excellent conformability to the curvature of the coronary artery 66. The results of the three-point bending test of Comparative Example 6 were comparable to those of Examples 1 to 6. However, as described above, it was confirmed that the conformability to the coronary artery 66 was inferior to that of Examples 1 to 6. This demonstrates that a flexible distal shaft 12 does not necessarily result in good conformability.

[0070] Furthermore, the distal shafts 12 of Examples 1 to 6 all had a maximum load value of 0.1 N or more in a three-point bending test, and the distal shafts 12 were also hard enough to achieve the pushability and other properties required for the distal shafts 12.

[0071] 15 shows the results of measuring the lengths of the distal tips for Examples 1 to 6 and Comparative Examples 1 to 6. This shows that the distal tips 18 in Examples 1 to 6 were approximately 4.5 mm, while the distal tips in Comparative Examples 1 to 6 were all approximately 1 to 2 mm long, indicating that Examples 1 to 6 were equipped with longer distal tips than Comparative Examples 1 to 6. As a result, when the distal shaft 12 is inserted into the tortuous coronary artery 66, the orientation of the flexible distal end portion 26 of the distal shaft 12 equipped with the long distal tip 18 quickly changes to a direction that is aligned with the coronary artery 66, which is thought to result in a higher ability to follow the coronary artery 66.

[0072] Note that Example 3 and Comparative Example 6 differ in the presence or absence of a ring marker, and the length of the distal tip 18 in Comparative Example 6 is shorter than in Example 3 due to the attachment of a ring marker. There is a significant difference between Example 3 and Comparative Example 6 in terms of trackability with respect to the left circumflex artery of the left coronary artery 66L, and it has been confirmed that Example 3 has superior trackability to Comparative Example 6 (see FIG. 11 ). For this reason, it is believed that one of the reasons for the improved trackability of the guide extension catheter 10 with respect to the coronary artery 66 is that, instead of the conventionally known hard ring marker, a flexible marker portion is used in which powder of a radiopaque material is mixed into the resin material from which the distal tip 18 is formed, and a flexible portion is provided in a long region from the distal end in the distal portion 26 of the distal shaft 12.

[0073] Furthermore, Figure 16 shows the results of a flexibility test of the distal portion of the distal shaft for Examples 1 to 6 and Comparative Examples 1 to 6. According to this, the maximum load values ​​for Examples 1 to 5 were all 1.5 N or less, while the maximum load value for Example 6 exceeded 2.0 N. Unlike Example 4, which was constructed according to the above-described embodiment, Example 6 has a structure in which an inner layer 20 formed of polytetrafluoroethylene (PTFE) is provided throughout the distal shaft 12 up to the tip of the distal tip 18, resulting in lower flexibility of the distal portion than Example 4. Note that Examples 4 and 6 exhibited similar levels of trackability in the trackability test shown in Figures 10A to 12A. However, in the trackability test for the right coronary artery 66R2 shown in Figure 13A, Example 4 could be inserted further distally than Example 6, and Example 4 exhibited better trackability than Example 6.

[0074] Furthermore, the distal portion 26 of the distal shaft 12 in Examples 1 to 5 is more flexible with respect to axial compression than the distal portion of the distal shaft 12' in Comparative Examples 1 to 3. Therefore, in Examples 1 to 5, when the distal portion 26 of the distal shaft 12 abuts against the inner wall surface of the coronary artery 66, the distal portion 26 including the distal tip 18 is more likely to deform than the main body portion 16 of the distal shaft 12, making it easier for the distal portion 26 of the distal shaft 12 to change direction in a direction parallel to the coronary artery 66. Furthermore, when the distal portion 26 of the distal shaft 12 comes into contact with the coronary artery 66, the coronary artery 66 can be prevented from being damaged by the distal shaft 12. The maximum load value in the flexibility test of the distal portion 26 of the distal shaft 12 is preferably 1.3 N or more and 1.5 N or less.

[0075] 17 shows the results of a kink resistance test of distal shafts conducted for Examples 1 to 3 and Comparative Examples 1 to 3. According to this, all of the distal shafts 12 of Examples 1 to 3 kinked when placed along the outer peripheral surface of a kink test jig 40 having an outer diameter of 2.0 mm, whereas the distal shafts 12' of Comparative Examples 2 and 3 kinked when placed along the outer peripheral surface of a kink test jig 40 having an outer diameter of 4.0 mm. Therefore, the distal shafts 12 of Examples 1 to 3 are less likely to kink even when bent with a smaller curvature than the distal shafts 12' of Comparative Examples 2 and 3, making it easier to avoid adverse effects on pushability due to kinking.

[0076] 18 shows the results of a distal shaft crush test conducted for Examples 1 to 3 and Comparative Examples 1 to 3. The results show that the maximum load values ​​for Examples 1 to 3 are all 4.0 N or greater, which indicates that the radial shape retention performance required for a distal shaft 12 with excellent flexibility is adequately ensured. Furthermore, while the maximum load values ​​for Examples 1 to 3 are all 6.0 N or less, the maximum load values ​​for Comparative Examples 1 and 3 are all greater than 6.0 N. Therefore, the main body portion 16 of the distal shaft 12 of Examples 1 to 3 is more susceptible to changes in cross-sectional shape due to the action of external force and more readily tolerates bending deformation and other deformations that accompany changes in cross-sectional shape than the main body portion 16' of the distal shaft 12' of Comparative Examples 1 and 3.

[0077] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to those specific descriptions. For example, in the above embodiment, the main body portion 16 of the distal shaft 12 has a structure in which the braided body 24 is provided between the inner layer 20 and the outer layer 22. However, the entire main body portion 16 may be formed from a synthetic resin material. Furthermore, the distal tip 18, which is provided on the distal shaft 12 distal to the main body portion 16, may be formed integrally with the main body portion 16 from the same synthetic resin material, or may be formed from a different material from the main body portion 16 and fixed thereto by means such as welding. Furthermore, the present invention originally includes each of the inventions described below in (i) to (vi), and the configurations and effects thereof will be described below. The present invention provides (i) A guide extension catheter having a tubular distal shaft provided at the distal end of a proximal shaft, wherein the main body of the distal shaft is placed on a support base of a three-point bending test jig in which the distance between the supports is set to 15 mm, and an indenter that moves toward the main body at a relative movement speed of 10 mm / min relative to the support base is pressed against the main body from the side at the central portion between the supports of the support base to deform the main body until a kink occurs. The maximum load value applied to the main body is 0.1 N or more and 0.6 N or less, and a distal tip that is more flexible than the main body is provided on the distal shaft distal to the main body, and the length of the distal tip is 2.5 mm or more, and the distal tip is equipped with a marker portion in which powder made of an X-ray opaque material is mixed. (ii) The guide extension catheter according to (i), wherein a coating layer made of a hydrophilic polymer is provided on the outer peripheral surface of the distal shaft in a length region extending from the tip of the distal shaft toward the base end, but not reaching the base end. (iii) The guide extension catheter according to (i) or (ii), wherein an anti-slip portion is provided on the outer circumferential surface of the proximal end portion of the distal shaft. (iv) The guide extension catheter according to any one of (i) to (iii), wherein the main body portion of the distal shaft is wound around a kink test jig having a cylindrical outer circumferential surface, and the outer diameter of the kink test jig is 3 mm or less. (v) The guide extension catheter according to any one of (i) to (iv), wherein the main body portion of the distal shaft has a maximum load value of 4.0 N or more when the main body portion is sandwiched radially between the support surface and the crushing jig and a load of 0.5 N is applied, and then the crushing jig is further pushed 0.5 mm in the direction approaching the support surface. (vi) A guide extension catheter according to any one of (i) to (v), wherein the distal tip is configured such that a portion of the distal shaft connected to the distal tip at a position 5 mm from the distal end toward the base end is restrained by a holding jig, and the distal end surface of the distal tip is brought into contact with a pressing jig, and the holding jig is moved toward the pressing jig at a pressing speed of 10 mm / min to compress the distal tip by 1 mm in the longitudinal direction, and the maximum load value is 0.5 N or more and 1.5 N or less. This includes inventions relating to: In the invention described in (i) above, the main body portion of the distal shaft is able to conform to the curvature of a blood vessel or the like due to bending deformation, while avoiding deterioration in pushability and kink resistance due to excessive flexibility. Therefore, the distal shaft achieves high conformability to the shape of a coronary artery or the like, allowing the distal shaft to be inserted further distally into the coronary artery or the like. Furthermore, by providing a certain degree of rigidity to the main body portion of the distal shaft and providing a distal tip that is more flexible than the main body portion, for example, when passing through a sharply curved portion of a coronary artery or the like, the distal tip, which easily conforms to the curved shape of the coronary artery, or the like, leads the main body portion. This makes it easier for the tip of the main body portion to face in the direction of extension of the coronary artery or the like, and the distal tip easily guides the main body portion in the direction of extension of the coronary artery or the like. To effectively realize this distal tip's function of guiding the main body portion, the distal tip must have a length that allows it to deform into a curved shape that conforms to the coronary artery or the like. Therefore, by setting the length of the distal tip to 2.5 mm or more, the flexible distal tip can be bent and deformed to effectively improve the distal shaft's passability through the coronary artery or the like. Conventional guide extension catheters have a ring marker attached to the distal end to ensure visibility of the distal end under X-ray fluoroscopy. However, the hard ring marker limits the flexible area of ​​the distal end, sometimes adversely affecting insertion. Therefore, in this embodiment, the marker portion for ensuring visibility under X-ray fluoroscopy is formed from a material containing a radiopaque powder, thereby providing sufficient flexibility. By providing such a flexible marker portion on the distal tip, visibility of the distal shaft's distal end under X-ray fluoroscopy is ensured, while preventing the effective length of the distal tip from being shortened by the attachment of a hard marker. This allows the distal shaft to achieve excellent followability to blood vessels, etc. The length of the distal tip varies depending on the flexibility of the material of the distal tip, but is preferably 10 mm or less.In particular, if the flexible distal tip is too long, deformation is likely to occur at the distal portion of the distal shaft formed by the distal tip, which may cause the lumen of the distal shaft to collapse and become blocked, or may increase resistance when inserted into a blood vessel. In the invention described in (ii) above, the lubricity of the outer peripheral surface of the distal shaft is improved, facilitating insertion when the distal shaft is inserted into a guiding catheter, a coronary artery, etc. Furthermore, since the coating layer is provided in a length region that does not reach the proximal end of the distal shaft, which is to remain within the guiding catheter, the coating layer does not make it difficult to position the distal shaft relative to the guiding catheter, and this prevents problems such as the distal shaft becoming dislodged from the guiding catheter. In the invention described in (iii) above, an anti-slip portion is provided at the base end portion of the distal shaft that should remain inside the guiding catheter, making it easier to position the distal shaft relative to the guiding catheter and preventing problems such as the entire distal shaft accidentally becoming exposed from the guiding catheter. In the invention described in (iv) above, the main body portion of the distal shaft is less likely to kink, which reduces the likelihood of reduced pushability due to kinking, improper insertion of the therapeutic catheter, etc. Moreover, the main body portion of the distal shaft can be bent to a smaller radius of curvature without kinking, which allows it to exhibit excellent followability around tortuous coronary arteries, etc. In the invention described in (v) above, the main body of the flexible distal shaft achieves excellent bending flexibility, which is thought to contribute to its ability to follow the coronary arteries, etc., while ensuring resistance to radial crushing, thereby stably maintaining its cross-sectional shape. Therefore, for example, it is possible to prevent the distal shaft from deforming into an elliptical cross section, which would increase the contact area with the coronary arteries, etc., and reduce resistance during insertion. In the invention described in (vi) above, the distal tip is sufficiently soft while maintaining the hardness (rigidity) required for insertion into the coronary artery, etc., thereby more advantageously ensuring the ability of the guide extension catheter to follow the coronary artery, etc. [Explanation of symbols]

[0078] 10,10' Guide Extension Catheter 12,12' Distal Shaft 14 Proximal Shaft 16,16' body part 18 Tip (marker part) 20 inner layer 22 Outer layer 24 Braid body 26 Tip part 28 Coating Layer 30 Support stand 32 Fulcrum 34 indenter 36 Holding jig 38 Pressing jig 40 Kink test fixture 42 Support surface 44 Crushing jig 46 Protective material 48 Connecting Tube 50 Guiding catheter 52 Catheter body 54 Contrast marker 56 Y connector 58 Sidearm 60 Balloon Catheter 62 Balloon 64 Catheter assembly 66 Coronary Arteries 68 Stenosis 70 Femoral artery 72 Sheath 74 Ascending aorta 76 Guidewire

Claims

1. A guide extension catheter having a tubular distal shaft provided at the distal end of a proximal shaft, In the main body portion of the distal shaft, the main body portion is placed on a support base of a three-point bending test jig in which the distance between the supports is set to 15 mm, and an indenter that moves toward the support base at a relative movement speed of 10 mm / min is pressed against the main body portion from the side at the center portion between the supports of the support base to deform the main body portion until a kink occurs. The maximum load value applied to the main body portion is 0.1 N or more and 0.6 N or less, The distal shaft is provided with a distal tip that is more flexible than the main body portion, and the distal tip is provided with a distal tip that is more flexible than the main body portion. The guide extension catheter has an anti-slip portion at the base end portion of the distal shaft, which has an outer circumferential surface with a higher coefficient of friction than the tip portion.

2. 2. The guide extension catheter according to claim 1, wherein a coating layer made of a hydrophilic polymer is provided on the outer surface of the distal shaft in a length region extending from the tip to the base end of the distal shaft but not reaching the base end.

3. 3. The guide extension catheter according to claim 1, wherein the main body portion of the distal shaft is wound around a kink test jig having a cylindrical outer circumferential surface, and the outer diameter of the kink test jig is 3 mm or less.

4. 4. The guide extension catheter according to claim 1, wherein the main body portion of the distal shaft has a maximum load value of 4.0 N or more when the main body portion is radially sandwiched between the support surface and the crushing jig and a load of 0.5 N is applied, and then the crushing jig is further pushed 0.5 mm in the direction approaching the support surface.

5. 5. The guide extension catheter according to claim 1, wherein the distal tip is configured such that the distal shaft connected to the distal tip at a position 5 mm from the distal end toward the base end is restrained by a holding jig, and the distal surface of the distal tip is brought into contact with a pressing jig, and the holding jig is then moved toward the pressing jig at a pressing speed of 10 mm / min to compress the distal tip by 1 mm in the longitudinal direction, with the maximum load value being 0.5 N or more and 1.5 N or less.

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