Catheter shaft and catheter device

Abstract

The present disclosure provides a catheter shaft that is easily pulled out of a body even when an external force is applied from a blood vessel due to spasm, and that is not easily broken when pulled out. A catheter shaft is provided with: a shaft main body having a multi-lumen structure; and at least one reinforcing layer embedded in the shaft main body and the catheter shaft, and performing a tensile test for stretching a test piece obtained from the catheter shaft under test conditions of a chuck-to-chuck distance of 30 mm and a tensile speed of 300 mm / min. When the tensile test is performed, the ratio of the amount of change in the minimum outer diameter after tensile at a predetermined position of the test piece relative to the minimum outer diameter before tensile is defined as a reduction ratio in%. When the percentage of change in the axial dimension after stretching of the catheter shaft with respect to the axial dimension before stretching is defined as the elongation in%, the shrinkage rate is 5% or more when the elongation reaches 100% when the test piece is not fractured in the tensile test, and the percentage of change in the axial dimension after stretching of the catheter shaft with respect to the axial dimension before stretching is defined as%.

Description

Technical Field

[0001] The present disclosure relates to a catheter device. Background Art

[0002] Patent Document 1 discloses a catheter device including a catheter shaft. The catheter shaft includes a shaft body having a multi-lumen structure and a reinforcing layer embedded in the shaft body.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-171372 Summary of the invention

[0006] Problems to be solved by the invention

[0007] Sometimes the catheter shaft is inserted through peripheral blood vessels in the hands, feet, etc. When the catheter shaft is inserted through a peripheral blood vessel or other thin blood vessel, abnormal vasoconstriction called spasm may occur in the blood vessel. When external force is applied from the blood vessel to the catheter shaft due to the spasm, there is a problem that the catheter shaft cannot be pulled out even if it is pulled toward the outside of the body (proximal side).

[0008] One of the objects of the present disclosure is to provide a catheter shaft that can be easily pulled out of the body and is not easily broken when pulled out even when an external force is applied from a blood vessel due to spasm.

[0009] Technical Solution

[0010] A catheter shaft of a certain scheme of the present disclosure comprises: a shaft body having a multi-lumen structure; and at least one reinforcement layer buried in the shaft body, wherein a tensile test is performed on a test piece obtained from the catheter shaft under test conditions of a chuck-to-chuck distance of 30 mm and a tensile speed of 300 mm / min, and a ratio of a change in the minimum outer diameter after stretching at a specified position of the test piece during the tensile test to the minimum outer diameter before stretching is set as a reduction rate, and the reduction rate is expressed in %, and a ratio of a change in the axial dimension of the catheter shaft after stretching to the axial dimension before stretching is set as an elongation, and the elongation is expressed in %, and at this time, when the elongation reaches 100% without the test piece breaking in the tensile test, the reduction rate is 5% or more.

[0011] A catheter shaft of another embodiment of the present invention comprises: a shaft body having a multi-lumen structure; and at least one reinforcement layer buried in the shaft body, wherein a tensile test is performed on a test piece obtained from the catheter shaft under test conditions of a chuck-to-chuck distance of 30 mm and a tensile speed of 300 mm / min, and a ratio of a change in the minimum outer diameter after stretching at a specified position of the test piece during the tensile test to the minimum outer diameter before stretching is set as a reduction rate, and the reduction rate is expressed in %. At this time, when a tensile load of 90 N is applied to the test piece in the tensile test, the reduction rate is greater than 20%.

[0012] Effects of the Invention

[0013] According to the present disclosure, it is possible to provide a catheter shaft that can be easily removed from the body even when an external force is applied from a blood vessel due to spasm and that is unlikely to break when removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 (A) is an explanatory diagram showing the state of the braided fabric before elongation and deformation. Figure 1 (B) is an explanatory diagram showing the state of the knitted fabric after elongation and deformation.

[0015] Figure 2 It is an overall view showing the catheter device according to the embodiment.

[0016] Figure 3 yes Figure 2 AA section view.

[0017] Figure 4 (A) is a diagram showing an example of a knitting pattern of a knitted fabric according to an embodiment, Figure 4 (B) is a diagram showing examples of other knitting patterns.

[0018] Figure 5 (A) is a schematic diagram showing a test piece used for a tensile test, Figure 5 (B) is a schematic diagram showing a state where the test piece is assembled in a tensile testing machine.

[0019] Figure 6 This is a graph showing the relationship between the elongation and the diameter reduction obtained by the tensile test.

[0020] Figure 7 This is a graph showing the relationship between the tensile load and the diameter reduction ratio obtained by the tensile test. DETAILED DESCRIPTION

[0021] The following is a description of the embodiments for implementing the present disclosure. The same or equivalent components are marked with the same figure numbers, and repeated descriptions are omitted. In each figure, for the convenience of description, the components are appropriately omitted, enlarged, or reduced. Observe the drawings according to the direction of the figure numbers. "Or" in this specification means that at least one of the two or more elements mentioned is established.

[0022] First, the background of the catheter shaft disclosed in the present invention is described. Assume a catheter shaft having a shaft body with a multi-lumen structure and at least one reinforcing layer embedded in the shaft body. The inventor of the present application conducted a study for the following situation: for such a catheter shaft, when an external force is applied from a blood vessel due to spasm, the catheter shaft can be easily pulled out of the body.

[0023] The reason for focusing on the multi-lumen structure is that, compared with the single-lumen structure, when the catheter shaft is pulled out due to the external force applied from the blood vessel by spasm, the catheter shaft is more likely to break. The reason may not be clear, but the following reasons can be considered. Compared with the single-lumen structure, in the case of the multi-lumen structure, it is easy to produce a thin wall thickness between the outer peripheral surface of the shaft body and the cavity or between adjacent cavities. Considering that in the case of the multi-lumen structure, compared with the single-lumen structure, the catheter shaft becomes easy to break due to the stress concentration generated in the thin wall thickness.

[0024] In the course of this study, the inventors of the present application have newly focused on the ease of thinning when the catheter shaft is stretched, based on the relationship with the ease of removal of the catheter shaft when an external force is applied from the blood vessel due to spasm. This is because when the catheter shaft is stretched, the catheter shaft is thinned at the portion where an external force is applied from the blood vessel, making it easier to remove the catheter shaft.

[0025] The inventors of the present application have discovered the concept of the diameter reduction rate of a catheter shaft that can be measured by a tensile test as a new index indicating the ease with which the catheter shaft can be thinned. When confirming the diameter reduction rate that can be achieved in a general multi-lumen structure catheter shaft, they have newly discovered that the maximum diameter reduction rate that can be achieved by the test piece is generally about 0% to 3% and does not exceed 5%.

[0026] Therefore, for the catheter shaft disclosed in the present invention, the ease of measuring the reduction ratio is taken into consideration in relation to the technical problem of easy extraction of the catheter shaft, so as to satisfy at least one of the following first shaft conditions or second shaft conditions related to the shaft. The first shaft condition is: when the elongation (described later) of the test piece reaches 100% without the test piece breaking in the tensile test, the reduction ratio is 5% or more. The second shaft condition is: when a tensile load of 90N is applied to the test piece without the test piece breaking in the tensile test, the reduction ratio is 20%. The elongation of the test piece here is a value indicating the ease of elongation of the catheter shaft. Any of the shaft conditions is based on the condition that the reduction ratio measured when the reference condition (the elongation of the test piece reaches 100% or the tensile load of 90N is applied to the test piece) is met during the tensile test, and is greater than the allowable value. The allowable value of the reduction ratio is set as a reference in relation to the technical problem of easy extraction of the catheter shaft. By satisfying at least one of the first axis condition or the second axis condition, the catheter shaft can be easily removed even when an external force is applied from a blood vessel due to spasm, and the catheter shaft is less likely to break during removal, compared to a case where the condition is not satisfied.

[0027] In addition, the inventors of the present application have newly discovered that there is a trend that the greater the maximum elongation that the test piece can achieve, the more conducive it is to increase the maximum diameter reduction that it can achieve. When confirming the relationship between the diameter reduction and the elongation of a catheter shaft with a general multi-lumen structure, it has been newly discovered that when the maximum diameter reduction is about 0% to 3%, the maximum elongation is less than 50% and does not exceed 100%. The idea for increasing the elongation that the test piece can achieve is explained.

[0028] Figure 1 (A) Figure 1 (B) is a diagram showing the state of the braid 42 constituting the reinforcement layer of the catheter shaft before and after the elongation deformation. Figure 1 In (A), the axial dimension of the mesh 43 of the braid 42 is P. Figure 1(B) shows a state where the braid 42 is stretched to a point where the axial dimension of the mesh 43 thereof becomes P'. The inventors of the present application have found that in terms of increasing the elongation, when the reinforcing layer is composed of the braid 42, it is important to focus not only on the ease of stretching the shaft body, but also on the ease of movement of the wires 40A and 40B when the braid 42 is stretched and deformed. The smaller the friction at the intersection of the wires 40A and 40B or the smaller the spacing between the wires 40A and 40B, the better the ease of movement of the wires 40A and 40B. The amount of elongation that can be stretched to the point where the resin shaft body itself breaks (hereinafter referred to as the "limit elongation") is usually much larger than the amount of elongation that can be stretched to the point where the braid 42 breaks. However, when the braid 42 is embedded in the shaft body, if the ease of movement of the wires 40A and 40B is too low, the following problem occurs: the elongation deformation of the shaft body is restrained by the braid 42 too early before the shaft body reaches the limit elongation. In this way, if the elongation deformation of the shaft body is restrained by the braid 42, the elongation deformation of the entire test piece is insufficient, which is not conducive to obtaining a large elongation.

[0029] Here, the inventors of the present application have found that, in terms of increasing the elongation that can be obtained by the test piece, it is effective to adjust the factors that affect the ease of movement of the wires 40A and 40B when the braid 42 is about to be elongated and deformed to appropriately increase the ease of movement of the wires 40A and 40B. By appropriately increasing the ease of movement of the wires 40A and 40B, it is possible to avoid the situation where the elongation deformation of the shaft body is restrained by the braid 42 too early before the shaft body reaches the limit elongation, which is conducive to obtaining a large elongation. The following is a description of the details of the catheter shaft conceived based on this idea.

[0030] Reference Figure 2 Hereinafter, when describing the positional relationship of the components of the catheter device 12, the axial direction, radial direction, and circumferential direction of the catheter shaft 10 are used for description, and these are simply referred to as “axial direction”, “radial direction”, and “circumferential direction”.

[0031] The catheter shaft 10 is used as a part of the catheter device 12. The catheter device 12 of the present embodiment is a balloon catheter in which a balloon 14 is attached to the catheter shaft 10. The specific example of the catheter device 12 is not particularly limited, and for example, it can also be used as an electrode catheter, a delivery catheter, a guide catheter, a foreign body removal catheter, an angiography catheter, a microcatheter, etc. The catheter shaft 10 is inserted into the body in order to treat a target organ such as a blood vessel. Here, "treatment" refers to an act related to the treatment or examination of a living body. The catheter shaft 10 is inserted into the body from, for example, a peripheral blood vessel in the hands, feet, etc.

[0032] The catheter device 12 includes a handle 16 attached to the proximal end of the catheter shaft 10 and gripped by an operator in addition to the catheter shaft 10. The catheter device 12 of this embodiment includes a balloon 14 attached to the distal end of the catheter shaft 10 as an optional configuration.

[0033] The catheter shaft 10 has flexibility that allows it to bend and deform. Here, an example is shown in which a curved portion 18 is provided in the middle of the axial direction of the catheter shaft 10. A tip member 20 is mounted at the distal end of the catheter shaft 10. The outer diameter (diameter) of the catheter shaft 10 is, for example, 5 Fr (1.67 mm) or more and 9.5 Fr (3.2 mm) or less.

[0034] Reference Figure 3 .exist Figure 3 , the entire range where each reinforcing layer 24A, 24B described later exists as viewed from the axial direction. In fact, in the cross section perpendicular to the axial direction, the wire material (described later) constituting the reinforcing layers 24A, 24B exists partially within the range showing the reinforcing layers 24A, 24B.

[0035] The catheter shaft 10 includes: a shaft body 22 having a multi-lumen structure; and at least one reinforcement layer 24A, 24B, which is embedded in the shaft body 22. The multi-lumen structure herein refers to a structure in which a plurality of lumens 26A, 26B are formed in the shaft body 22. An example in which the number of lumens 26A, 26B is two is shown here, but the number may be three or more. The plurality of lumens 26A, 26B in the present embodiment include a main lumen 26A and a sub-lumen 26B. In the present embodiment, in a cross section of the catheter shaft 10 orthogonal to the axial direction, the cross-sectional area of ​​the main lumen 26A is larger than the cross-sectional area of ​​the sub-lumen 26B. The size relationship between the cross-sectional areas of the lumens is not particularly limited, and the cross-sectional areas of all lumens may be the same.

[0036] Each of the multiple cavities 26A and 26B is used to allow at least one of the medical device or fluid to pass through. The main cavity 26A of the present embodiment is used to allow the medical device to pass through. The secondary cavity 26B of the present embodiment is used to allow the fluid for expanding the balloon 14 to pass through. The medical devices that should pass through each cavity 26A and 26B are, for example, guide wires, stent grafts, coils, wiring components, etc., as well as various catheters such as electrode catheters, balloon catheters, and microcatheters. The wiring components here refer to, for example, flexible substrates for wiring that are electrically connected to electrical equipment attached to the catheter shaft 10. The electrical equipment here is, for example, an ultrasonic transducer for ICE (Intracardiac Echocardiography). The fluid that should pass through each cavity 26A and 26B is, for example, a fluid for expanding the balloon 14, and liquids such as contrast fluids, flushing liquids (such as saline) and the like.

[0037] Objects to be passed through the cavities 26A and 26B are introduced from outside the body into the cavities 26A and 26B through the introduction ports 28A and 28B provided on the handle 16, and are discharged out of the cavities 26A and 26B through the discharge ports 30A and 30B provided on the catheter shaft 10. Figure 2 , a first inlet port 28A and a first outlet port 30A corresponding to the main cavity 26A, and a second inlet port 28B and a second outlet port 30B corresponding to the sub-cavity 26B are shown.

[0038] The shaft body 22 includes at least one resin layer. The shaft body 22 of this embodiment includes an inner layer 32, an intermediate layer 34 covering the inner layer 32, and an outer layer 36 covering the intermediate layer 34 as such resin layers. The main cavity 26A is formed by the inner layer 32, and the sub-cavity 26B is formed by the intermediate layer 34.

[0039] The reinforcing layers 24A and 24B are used to reinforce the shaft body 22. The reinforcing layers 24A and 24B of the present embodiment include an inner reinforcing layer 24A surrounding the main cavity 26A and an outer reinforcing layer 24B surrounding the main cavity 26A and the sub-cavity 26B.

[0040] It should be noted that the number of resin layers constituting the shaft body 22 and the number of reinforcing layers embedded in the shaft body 22 are not particularly limited. In addition, the positions of the reinforcing layers and cavities in the shaft body 22 are also not particularly limited. For example, only one of the inner reinforcing layer 24A and the outer reinforcing layer 24B may be present as a reinforcing layer, or a reinforcing layer different from these may be present as a reinforcing layer.

[0041] Reference Figure 4 (A) Figure 4 (B). Figure 4 (A) Figure 4 (B) is a cross-sectional view of a portion of the braid 42 constituting the reinforcing layer 24A observed from the radially outer side. The reinforcing layers 24A and 24B of this embodiment are braids 42 formed by braiding a plurality of wires 40A and 40B into a cylindrical and mesh shape. The reinforcing layers 24A and 24B may also be formed by coils formed of spiral wires instead of the braid 42.

[0042] The braid 42 is composed of a plurality of first wires 40A extending toward one side in the circumferential direction as it moves toward one side in the axial direction, and a plurality of second wires 40B extending toward the other side in the circumferential direction as it moves toward one side in the axial direction. The plurality of first wires 40A intersect with the plurality of second wires 40B. The braid 42 forms a plurality of meshes 43 by the plurality of wires 40A and 40B. The meshes 43 are formed as gaps and have a rhombus shape at the locations surrounded by the first wires 40A adjacent to the circumferential direction and the second wires 40B adjacent to the circumferential direction.

[0043] The braided fabric 42 is woven in a braided pattern formed by repeating the following braiding units, wherein the first wire 40A and the second wire 40B are respectively raised and lowered relative to the other wires in their axial directions. Figure 4 (A) shows a half pattern (two over two under pattern), Figure 4 The full pattern (one over one under pattern) shown in (B). Figure 4 The half pattern of (A) is obtained by repeating a weaving unit in which the first wire 40A sequentially passes through the radially outer sides of two second wires 40B and the radially inner sides of two second wires 40B. Figure 4 The full pattern of (B) is formed by repeating the following weaving unit, wherein the weaving unit is a weaving unit formed by the first wire 40A passing through the radial outer side of the second wire 40B and the radial inner side of the second wire 40B in sequence. The number of wires (such as the second wire 40B) that cross one wire (such as the first wire 40A) in each weaving unit is called the number of wire crossings per weaving unit. The number of wire crossings per weaving unit of the half pattern is four, and the number of wire crossings per weaving unit of the full pattern is two. The weaving pattern of the braid 42 cited here is only an example, and various other weaving patterns may also be used.

[0044] Next, a tensile test for measuring the elongation and diameter reduction of the catheter shaft 10 will be described. Figure 5 In this tensile test, a test piece 50 obtained by cutting the catheter shaft 10 in an axial dimension of 100 mm was used. In this test piece 50, a marking line portion 50a was provided by marking a marking line at the central position in the axial direction (the axial position 50 mm from the axial end) with a marker.

[0045] Before the tensile test, the outer diameter of the marked line portion 50a of the test piece 50 before the tensile test is measured by a non-contact outer diameter measuring machine. At this time, the minimum outer diameter (diameter) of the marked line portion 50a of the test piece 50 in the cross section perpendicular to the axial direction is measured. The minimum outer diameter here refers to the minimum value of the measured values ​​obtained when the outer diameter of the marked line portion 50a of the test piece 50 is measured by the outer diameter measuring machine in a manner covering the entire circumference.

[0046] Reference Figure 5(B). The tensile test is performed in a manner that satisfies the items listed in the following "Conditions". For example, the tensile tester uses the model EZ Test EZ-LX manufactured by Shimadzu Corporation, and the pneumatic chuck uses the model PFG-5kNA. Specific examples of the tensile tester and the pneumatic chuck are not limited as long as they meet the following conditions. The test piece 50 stretched by the tensile test is sometimes uniformly reduced to a circular shape, and sometimes reduced to a flat shape.

[0047] (condition)

[0048] Tensile testing machine with a rated capacity of 5 kN using a load cell

[0049] To prevent damage caused by direct contact between the air chuck 54 and the test piece 50, silicone tubes 52 (3 mm inner diameter, 5 mm outer diameter) are placed on both ends of the test piece 50 (the silicone tube 52 may also extend from the air chuck 54).

[0050] ·Use a pair of pneumatic chucks 54 with a maximum capacity of 5 kN and set the chuck pressure to 0.6 MPa to clamp the upper and lower ends of the test piece 50 so that the silicone tube 52 does not move.

[0051] Under the test conditions that the distance between the pair of air chucks 54 , that is, the inter-chuck distance, was set to 30 mm and the pulling speed was set to 300 mm / min, the test piece 50 was pulled by moving one of the air chucks 54 .

[0052] The tensile test is terminated when the test piece 50 is stretched until the prescribed test termination condition is met. The test termination condition here is that the elongation of the test piece 50 (described later) reaches the prescribed elongation (here 100%) without the test piece 50 breaking. If the test piece 50 breaks before the test termination condition is met, the tensile test is terminated. After the tensile test is completed, the tensile load applied to the test piece 50 is released and the test piece 50 is taken out of the tensile testing machine. Thereafter, the reduction rate of the test piece 50 described below is measured with respect to the test piece 50 provided for the tensile test. In addition, for the test piece 50 stretched to the prescribed elongation without the test piece 50 breaking, it is determined whether the reinforcing layers 24A and 24B are exposed.

[0053] Whether the test piece 50 is broken is determined by visual inspection. “The test piece 50 is broken” means that the reinforcing layers 24A and 24B of the test piece 50 and the shaft body 22 are not connected to each other but are completely separated in the axial direction.

[0054] The axial dimension of the test piece 50 before stretching is set to L0 (mm), the axial dimension of the test piece 50 after stretching is set to L1 (mm), and the change in the axial dimension of the test piece 50 after stretching is set to ΔL (=|L1-L0|). The change in the axial dimension ΔL is represented by the movement of the pneumatic chuck 54 on one side in the tensile test. At this time, the elongation (%) of the test piece 50 is the ratio of the change in the axial dimension ΔL of the test piece 50 after stretching relative to the axial dimension L0 (mm) of the test piece 50 before stretching, and is represented by the following formula (1). According to the following formula (1), the elongation is a value that can be calculated in sequence according to the movement (ΔL) of the pneumatic chuck 54 in the tensile test.

[0055] Elongation (%) = (ΔL / L0) × 100……(1)

[0056] The minimum outer diameter (diameter) before stretching at the specified position of the test piece 50 is set to Φ0 (mm), the minimum outer diameter (diameter) after stretching at the specified position of the test piece 50 is set to Φ1 (mm), and the change in the minimum outer diameter after stretching is set to ΔΦ (=|Φ0-Φ1|). At this time, the diameter reduction rate (%) of the test piece 50 is the ratio of the change ΔΦ of the minimum outer diameter after stretching to the minimum outer diameter Φ0 before stretching, which is expressed by the following formula (2). The specified position here refers to the axial center position where the marking portion 50a of the test piece 50 is located.

[0057] Diameter reduction ratio (%) = (ΔΦ / Φ0) × 100……(2)

[0058] The axial range of the marking line portion 50a±10mm is observed with a microscope at a magnification of 50 times to determine whether the reinforcing layers 24A and 24B are exposed. In this specification, "the reinforcing layers 24A and 24B are exposed to the outside" means that the reinforcing layers 24A and 24B are exposed to the outside space due to the partial cracking of the shaft body 22 of the test piece 50. In terms of satisfying the condition of "the reinforcing layer is exposed to the outside", in the case of having multiple reinforcing layers 24A and 24B, it is sufficient that at least one reinforcing layer 24A and 24B is exposed to the outside. In terms of satisfying the condition of "the reinforcing layer is exposed to the outside", only the inner reinforcing layer 24A may be exposed to the outside, only the outer reinforcing layer 24B may be exposed to the outside, or both the inner reinforcing layer 24A and the outer reinforcing layer 24B may be exposed to the outside.

[0059] The diameter reduction ratio when the test piece 50 satisfies the reference condition is an index indicating the ease of thinning when the catheter shaft 10 to which an external force is applied from a blood vessel due to spasm is stretched. The larger the diameter reduction ratio is, the easier it is to thin the catheter shaft 10 in the contracted blood vessel by stretching the catheter shaft 10 to the outside (proximal side) of the body in a state where an external force is applied from a blood vessel, and the easier it is to pull the catheter shaft 10 out of the blood vessel. From such a viewpoint, the catheter shaft 10 is conditioned to have a diameter reduction ratio of 5% or more when the elongation ratio of the test piece 50 reaches 100% (when the first reference condition is satisfied) without the test piece 50 breaking. From the same viewpoint, the diameter reduction ratio of the catheter shaft 10 is preferably 10% or more, and more preferably 15% or more when the elongation ratio reaches 100%. As a shaft to which the present invention is applied, the lower limit of the diameter reduction ratio allowed is a value greater than 0% to 3% which is a normal value in the catheter shaft 10 of a multi-lumen structure, which is defined using a reference value. The upper limit of the diameter reduction ratio when the elongation of the test piece 50 reaches 100% when the test piece 50 is not broken is not particularly limited, but is actually 80%.

[0060] In addition, the catheter shaft 10 is provided under the condition that the elongation of the test piece 50 reaches 100% when the test piece 50 is not broken. Thus, the catheter shaft 10 can be easily pulled out, and the catheter shaft 10 is not easily broken when pulled out.

[0061] The catheter shaft 10 is conditioned so that the reinforcing layers 24A and 24B are not exposed to the outside when the elongation of the test piece 50 reaches 100% in the tensile test as described above. Thus, in the process of pulling out the catheter shaft 10 to which an external force is applied from a blood vessel, the reinforcing layers 24A and 24B are not exposed from the shaft body 22 before the elongation of the test piece 50 reaches 100%. Therefore, the risk of the exposed reinforcing layers 24A and 24B rubbing against the living tissue can be reduced.

[0062] The elongation that the test piece 50 can obtain has the following tendency: the greater the elongation that the test piece 50 can obtain, the more advantageous it is to increase the diameter reduction rate that the test piece 50 can obtain. Based on this viewpoint, the lower limit of the elongation that is allowed for the catheter shaft to which the present invention is applied is preferably the larger the elongation is from 100% elongation on the 100% scale. That is, the lower limit of the elongation is preferably in the order of 200%, 300%, 400%, and 500%. The upper limit of the elongation is not particularly limited, but is actually 1000%. All of these are based on the premise that the test piece 50 is not broken.

[0063] In order to increase the elongation without breaking the test piece 50, when the braid 42 is used as the reinforcing layer 24A, 24B, it is preferable to adjust the factors that affect the ease of movement of the wires 40A, 40B when the braid 42 is stretched and deformed, on the premise of selecting the material of the shaft body 22 having the ease of elongation that can achieve the elongation. As described above, the smaller the friction force at the intersection of the wires 40A, 40B or the smaller the spacing between the wires 40A, 40B, the better the ease of movement of the wires 40A, 40B.

[0064] The inventors of the present application have newly discovered that factors that affect the ease of movement of the wires 40A and 40B include (1) the cross-sectional shape of the wires 40A and 40B, (2) the number of strands of the wires 40A and 40B, (3) the braiding pattern of the braid 42, (4) the surface roughness and friction coefficient of the wires 40A and 40B, and (5) the spacing between the wires 40A and 40B. Among these factors, (1) to (4) are factors related to the friction force at the intersection of the wires 40A and 40B.

[0065] (1) The cross-sectional shape of the wires 40A and 40B affects the contact area at the intersection of the wires 40A and 40B. In terms of reducing the friction at the intersection, a cross-sectional shape that can reduce the contact area is preferred. From this point of view, for the cross-sectional shape of the wires 40A and 40B, using a circular cross-sectional shape with a reduced contact area is more conducive to improving the ease of movement of the wires 40A and 40B than using a flat cross-sectional shape with an increased contact area at the intersection.

[0066] (2) The number of strands of the wires 40A and 40B (the number of wires constituting the wires 40A and 40B) also affects the contact area at the intersection of the wires 40A and 40B. In terms of reducing the friction at the intersection, the smaller the number of strands, the more preferable it is. From this point of view, the case where the number of strands is one is more conducive to improving the ease of movement of the wires 40A and 40B than the case where the number of strands is multiple.

[0067] (3) The weaving pattern of the braid 42 affects the vertical resistance at the intersection of the wires 40A and 40B. In terms of reducing the friction at the intersection, a weaving pattern with a large number of wire crossings per weaving unit is preferred. According to this view, for the weaving pattern of the braid 42, using a weaving pattern with a large number of wire crossings (e.g., a half pattern) is more conducive to improving the ease of movement of the wires 40A and 40B than using a weaving pattern with a small number of wire crossings per weaving unit (e.g., a full pattern).

[0068] In order to reduce the frictional force at the intersection of the wires 40A and 40B, the wires 40A and 40B may be subjected to a surface treatment for reducing either the surface roughness or the friction coefficient of the wires 40A and 40B in (4).

[0069] In terms of improving the ease of movement of the wires 40A and 40B, it is more preferable to make the inclination angle of the wires 40A and 40B steeper with respect to the axial direction. According to this viewpoint, for the spacing of the wires 40A and 40B in (5), a narrow spacing is more conducive to improving the ease of movement of the wires 40A and 40B than a wide spacing. The spacing here refers to the axial dimension P of the mesh 43 of the braid 42 (refer to Figure 1 ).

[0070] In order to adjust the elongation without breaking the test piece, at least one of the factors (1) to (5) may be adjusted. In other words, it can be said that the catheter shaft 10 is adjusted to satisfy the elongation condition (e.g., a condition of 100% or more).

[0071] It should be noted that, when a coil is used as the reinforcing layer 24A, 24B, the coil pitch (pitch angle), the wire diameter, the number of strands, the material, the cross-sectional shape, etc. of the wire can also be adjusted in terms of adjusting the elongation. For example, in terms of increasing the elongation, the coil pitch can be reduced, the wire diameter can be thinned, or the number of strands can be reduced so that the wire can be easily elongated and deformed in the axial direction. In addition, in terms of increasing the elongation, the material and the cross-sectional shape can also be adjusted so that the wire can be easily elongated and deformed in the axial direction.

[0072] The material of the shaft body 22 that has the ease of elongation that can achieve the above elongation refers to resins such as PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy fluororesin), PEBAX (polyether block amide, registered trademark), PA12 (polyamide 12), and TPU (thermoplastic polyurethane). In terms of increasing the elongation, it is better to use a material that is easy to stretch as the material of the shaft body 22. In addition, the material of the wires 40A and 40B is not particularly limited, but for example, metals such as stainless steel and Ni-Ti alloys can also be used. In addition, resins can also be used as the material of the wires 40A and 40B.

[0073] It should be noted that in terms of adjusting the reduction ratio, the elongation ratio itself can be adjusted, and the factors affecting the elongation ratio (factors affecting the ease of elongation of the material of the shaft body 22 and the ease of movement of the wires 40A and 40B) can also be adjusted. For example, in terms of increasing the reduction ratio, an adjustment method for increasing the elongation ratio can also be adopted. In addition, in terms of increasing the reduction ratio and elongation ratio without exposing the reinforcing layers 24A and 24B to the outside, the following (1) to (3) can also be adjusted separately within the range allowed by the design. (1) is the material of the shaft body 22, (2) is the wall thickness of the portion of the shaft body 22 that is radially outward of the reinforcing layers 24A and 24B (the outer layer 36 mentioned in the embodiment), and (3) is a factor that affects the ease of movement of the wires 40A and 40B. For example, the material of the shaft body 22 in (1) is preferably a material that is easy to stretch. In terms of adopting such a material that is easy to stretch, the lower the hardness of the resin material, the easier it is to stretch, so it is preferable to adopt a resin material with low hardness. For example, low-hardness PEBAX is easier to stretch than high-hardness PEBAX, and is therefore preferably the material of the shaft body 22. In addition, in order to improve the imaging properties, inorganic substances such as barium sulfate are sometimes added to the material of the shaft body 22. The more inorganic substances are added, the more difficult it is for the shaft body 22 to stretch. Therefore, in terms of adopting a material that is easy to stretch, it is preferable to adopt a material that minimizes the amount of inorganic substances added or does not add inorganic substances. By making the local wall thickness of the shaft body 22 (2) thicker, it is helpful to avoid the exposure of the reinforcing layers 24A and 24B due to local cracking of the shaft body 22. The wires 40A and 40B can also be made easy to move by adjusting the factors that affect the ease of movement of the wires 40A and 40B (3). If the wires 40A and 40B are difficult to move when the shaft body 22 is stretched and deformed, the stretching deformation of the shaft body 22 will be restrained by the braid 42 at an early stage as described above, which may cause the shaft body 22 to partially crack starting from the contact point between the shaft body 22 and the braid 42. By making the wires 40A and 40B easy to move, the stretching deformation of the shaft body 22 is prevented from being restrained by the braid 42 at an early stage, which is conducive to avoiding the exposure of the reinforcing layers 24A and 24B due to the local cracking of the shaft body 22.

[0074] The maximum load (N) that can be applied to the test piece 50 during the period before the test piece 50 breaks in the tensile test is preferably 90N or more. The "maximum load" refers to the maximum tensile load that can be applied to the test piece 50 during the period from the start of stretching the test piece 50 to the breakage of the test piece 50. The inventors of the present application have found that when the catheter shaft 10 is applied with a tensile load by the operator stretching the catheter shaft in a state where an external force is applied from the blood vessel, the tensile load is usually less than 90N. By satisfying the condition of the maximum load, the breakage of the catheter shaft 10 can be avoided as long as it is within the range of the tensile load usually applied by the operator.

[0075] The stretching amount of the test piece 50 when the test piece 50 reaches the maximum load (the change in the axial dimension of the test piece 50 before and after stretching) is called the stretching amount at the maximum load. At this time, the way in which the tensile load applied to the test piece 50 changes from the start of stretching the test piece to the stretching amount at the maximum load is not particularly limited. For example, the tensile load applied to the test piece 50 during the period from the start of stretching the test piece 50 to the reaching of a specified stretching amount (for example, 3 / 4 of the stretching amount at the maximum load) can be less than 90N, and the tensile load can also reach 90N or more during this period.

[0076] In terms of adjusting the maximum load that can be applied to the test piece 50 by the tensile test, when the reinforcing layers 24A and 24B are the braid 42, it is sufficient to adjust the total value of the breaking strength of the wires 40A and 40B. The total value of the breaking strength of the wires 40A and 40B is affected by (1) the cross-sectional area of ​​the wires 40A and 40B, (2) the number of ingots (number of meshes 43 in a cross section perpendicular to the axial direction) of the braid 42, and the like. The larger the cross-sectional area of ​​the wires 40A and 40B of (1), the more advantageous it is to increase the breaking strength. The greater the number of ingots of (2), the more advantageous it is to increase the breaking strength. The catheter shaft 10 is preferably configured to achieve the maximum load (90N or more) of the above conditions by adjusting either (1) or (2). It should be noted that when the reinforcing layers 24A and 24B are coils, it is sufficient to adjust (1) to achieve the maximum load (90N or more) of the above conditions.

[0077] The maximum load (N) that can be applied to the test piece 50 by the tensile test preferably satisfies the following conditions. The following conditions define the breaking strength required of the catheter shaft 10 as specified in ISO 10555 (General requirements for intravascular catheters supplied in a sterile state and intended for single use). By satisfying the following conditions, the minimum breaking strength required of the catheter shaft 10 in ISO can be ensured.

[0078] (condition)

[0079] 0.55mm≤φ0<0.75mm: Maximum load is 3N or more

[0080] 0.75mm≤φ0<1.15mm: Maximum load is 5N or more

[0081] 1.15mm≤φ0<1.85mm: Maximum load is 10N or more

[0082] 1.85mm≤φ0: Maximum load is 15N or more

[0083] The catheter shaft 10 preferably satisfies the condition that the reinforcing layers 24A and 24B are not exposed to the outside when a tensile load of 90N is initially applied to the test piece 50 in the tensile test. Here, "when a tensile load of 90N is initially applied to the test piece 50" means when a tensile load of 90N is first applied in the process of increasing the tensile load applied to the test piece 50 in the tensile test. Thus, when the catheter shaft 10 is stretched in a state where an external force is applied from a blood vessel, as long as the tensile load is within the range of the tensile load normally applied by the operator (less than 90N), the reinforcing layers 24A and 24B are exposed to the outside due to partial rupture of the shaft body 22. In terms of satisfying this condition, the adjustment method used to increase the reduction rate and elongation rate without exposing the reinforcing layers 24A and 24B to the outside may also be used.

[0084] So far, the axis condition that the catheter shaft 10 should satisfy has been described by taking the first axis condition that the diameter reduction rate measured when the elongation of the test piece 50 reaches 100% when the test piece 50 is not broken in the tensile test as an example, which is 5% or more. Alternatively, the axis condition that the catheter shaft 10 should satisfy may be the second axis condition that the diameter reduction rate is 20% or more when the test piece 50 is stretched to start applying a tensile load of 90N in the tensile test. In this case, the tensile test is terminated immediately after the tensile load of 90N is stretched in the tensile test. Thereafter, the tensile load applied to the test piece 50 is released, and the diameter reduction rate measured for the test piece 50 taken out of the tensile tester is sufficient to be 20% or more. In terms of satisfying the second axis condition, it is a premise that the test piece 50 is not broken when stretched to start applying a tensile load of 90N. In this case, it is also good to satisfy the condition that the reinforcing layers 24A and 24B are not exposed to the outside when the tensile load of 90N is started to be applied to the test piece 50. It should be noted that at the time point when the tensile load of 90N was applied in the tensile test, the elongation of the test piece 50 exceeded 100%, which was greater than the diameter reduction when the elongation reached 100%. According to this relationship, the allowable value of the diameter reduction that should be satisfied under the second axis condition (20%) is greater than the allowable value of the diameter reduction that should be satisfied under the first axis condition (5%).

[0085] Next, the tensile test performed to confirm the relationship between the above reduction rate and the elongation rate is described. In this tensile test, a tensile test is performed by using a test piece 50 under the conditions shown in the following Table 1 to stretch the test piece until a predetermined elongation rate is reached. In Table 1, in addition to recording the type of the test piece, the elongation ease of the resin material of the shaft body of each type, the cross-sectional shape of the wire, and the number of ingots are also recorded. For the cross-sectional shape of the wire, the cross-sectional shape of the outer reinforcing layer 24B and the cross-sectional shape of the inner reinforcing layer 24A are recorded in sequence. Types A and E are examples in which only the spacing of the wires is changed.

[0086] [Table 1]

[0087]

[0088] The test results are explained. In Table 1, as the results of the tensile test of each test piece 50, in addition to the minimum outer diameter before stretching, the minimum outer diameter after stretching, the elongation, and the diameter reduction rate, the maximum load, whether the reinforcing layers 24A and 24B are exposed, and whether the test piece 50 is broken. The maximum load in Table 1 represents the maximum load applied from the start of stretching the test piece 50 until the specified elongation is reached. No. 9 (type B) and No. 18 (type D) are examples of breaking from the start of stretching to stretching until the elongation reaches 50%.

[0089] Figure 6 It is a graph showing the results of the above tensile test. Types B and D break when the maximum elongation is less than 50%, which is an example in which the reduction rate cannot be made 5% or more when the elongation reaches 100% without the test piece breaking. In contrast, types A, C, and E are examples in which the reduction rate can be made 5% or more when the elongation is 100% without the test piece breaking. In addition, according to their comparison, it can be seen that when the elongation reaches 100% without the test piece breaking, it is beneficial to make the reduction rate 5% or more. In addition, according to Figure 6 It can be seen that there is a tendency that the greater the elongation that can be obtained without breaking the test piece 50, the more favorable it is to increase the diameter reduction rate. For example, if the type E in which the test piece 50 can obtain an elongation of less than 300% is compared with the types A and C in which the test piece 50 can obtain an elongation of more than 300%, it can be seen that the latter can obtain a greater diameter reduction rate.

[0090] In addition, according to the comparison between types A and E, it can be seen that, in the order of E→A, the narrower the wire spacing, the more conducive it is to increase the elongation and diameter reduction that can be obtained. In addition, according to the comparison between types A and C, it can be seen that compared with the flat cross-sectional shape of the wire, the cross-sectional shape of the wire is a circular cross-sectional shape, which is more conducive to increasing the elongation and diameter reduction that can be obtained.

[0091] Figure 7 This is a graph showing the relationship between the tensile load and the diameter reduction rate for the results shown in Table 1. Types B and D broke before the tensile load of 90 N was applied to the test piece, and the diameter reduction rate at the beginning of the tensile load of 90 N was not 20% or more. Types A, C, and E are examples of the diameter reduction rate at the beginning of the tensile load of 90 N being applied to the test piece being 20% ​​or more.

[0092] The above embodiments are examples. The technical ideas obtained by abstracting them should not be interpreted as the contents of the embodiments in a restrictive manner. Many design changes such as changing, adding, and deleting the components of the embodiments can be made to the contents. In the embodiments, the expression "implementation method" is added to emphasize the contents that can make such design changes. However, even if there is no such expression, design changes are allowed. The hatching marked in the cross-section of the accompanying drawings does not limit the material of the object marked with the hatching.

[0093] The maximum diameter reduction and elongation of the test piece 50 that can be obtained in a state where the reinforcing layers 24A and 24B are not exposed can also be measured by the following procedure.

[0094] (1) First, a primary tensile test is performed in which the test piece 50 is stretched until it breaks. In the primary tensile test, the elongation of the test piece 50 when the test piece 50 breaks is measured.

[0095] (2) Next, a second tensile test is performed using a test piece 50 obtained from the same sample as the test piece 50 used in the first tensile test. In the second tensile test, the test piece 50 is stretched to an elongation of -10% of the elongation measured in the first tensile test. Thereafter, it is determined whether the reinforcing layer of the test piece 50 obtained by the tensile test is exposed.

[0096] (3) In the case where the reinforcing layer is exposed in (2), the following series of steps are performed again: a tensile test is performed to an elongation of the elongation achieved in the previous tensile test minus 10%, and the reinforcing layer of the test piece 50 obtained by the tensile test is judged whether it is exposed. This series of steps is repeated until a test piece 50 is obtained in which the reinforcing layer is not exposed after the tensile test.

[0097] (4) After obtaining the test piece 50 in which the reinforcing layer is not exposed after the tensile test in (2) and (3), the diameter reduction rate of the test piece 50 is measured. The diameter reduction rate of the test piece 50 measured in this way and the elongation rate achieved in the tensile test on the test piece 50 can also be used as the maximum diameter reduction rate and elongation rate that can be obtained for the test piece 50 in the state where the reinforcing layer is not exposed.

[0098] Description of Reference Numerals

[0099] 10: catheter shaft; 12: catheter device; 22: shaft body; 24A, 24B: reinforcement layer; 26A, 26B: lumen; 40A, 40B: wire; 42: braid; 50: test piece.

Claims

1. A catheter shaft, comprising: The shaft body is a multi-cavity structure; and At least one reinforcement layer is embedded in the shaft body, wherein Under the test conditions of a chuck-to-chuck distance of 30 mm and a tensile speed of 300 mm / min, a tensile test is performed on the test piece obtained by stretching the catheter shaft, and the ratio of the change in the minimum outer diameter after stretching at a specified position of the test piece during the tensile test to the minimum outer diameter before stretching is set as a reduction rate, and the reduction rate is expressed in %. The ratio of the change in the axial dimension of the catheter shaft after stretching to the axial dimension before stretching is set as an elongation, and the elongation is expressed in %. At this time, when the elongation reaches 100% without the test piece breaking in the tensile test, the reduction rate is 5% or more.

2. The catheter shaft of claim 1, wherein: When the elongation reaches 100% in the tensile test, the reinforcing layer is not exposed to the outside.

3. The catheter shaft of claim 1, wherein: The reinforcing layer is a braided material formed by braiding a plurality of wires into a cylindrical and mesh shape. Factors affecting the ease of movement of the wire material when the braided fabric is to be elongated and deformed are adjusted so that the elongation becomes 100% or more.

4. The catheter shaft of claim 1, wherein: In the tensile test, the maximum tensile load that can be applied to the test piece before the test piece breaks is 90N or more, and the unit of the tensile load is N.

5. The catheter shaft of claim 1, wherein: When a tensile load of 90 N was applied to the test piece at the beginning of the tensile test, the reinforcing layer was not exposed to the outside.

6. A catheter shaft, comprising: The shaft body is a multi-cavity structure; and At least one reinforcement layer is embedded in the shaft body, wherein Under the test conditions of a chuck-to-chuck distance of 30 mm and a tensile speed of 300 mm / min, a tensile test is performed on the test piece obtained by stretching the catheter shaft, and the ratio of the change in the minimum outer diameter after stretching at a specified position of the test piece during the tensile test to the minimum outer diameter before stretching is set as the reduction rate, and the reduction rate is expressed in %. At this time, when a tensile load of 90 N is applied to the test piece at the beginning of the tensile test, the reduction rate is greater than 20%.

7. A catheter device, wherein: The catheter device includes the catheter shaft according to any one of claims 1 to 6.

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