Catheter shaft and catheter device

Abstract

To provide a catheter shaft that is easy to be withdrawn out of the body even when external force is applied from a blood vessel due to spasm and is resistant to breakage during withdrawal.SOLUTION: A catheter shaft comprises a shaft body with a multi-lumen structure and at least one reinforcement layer embedded in the shaft body. When a ratio of a change amount in the minimum outer diameter after pulling to the minimum outer diameter before pulling at a prescribed position of a test piece in a case where a pulling test of pulling the test piece obtained from the catheter shaft is performed under a test condition in which an inter-chuck distance is 30 mm, and a pulling speed is 300 mm / min is a diameter reduction ratio (%), and a ratio of a change amount in the dimension in the axial direction after pulling to the dimension in the axial direction before pulling of the catheter shaft is an elongation ratio (%), the diameter reduction ratio is equal to or greater than 5% in a case where the test piece does not break and the elongation ratio is 100% in the pulling test.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to catheter devices. [Background technology]

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

[0003] [Patent Document 1] JP 2018-171372 A Summary of the Invention [Problem to be solved by the invention]

[0004] There are cases where a catheter shaft is inserted through a peripheral blood vessel in a hand, foot, etc. When a catheter shaft is passed through a small blood vessel such as a peripheral blood vessel, an abnormal vasoconstriction called spasm may occur in the blood vessel. If an external force is applied to the catheter shaft from the blood vessel due to this spasm, there is a problem that the catheter shaft cannot be removed even if it is pulled to the outside of the body (proximal side).

[0005] One object of the present disclosure is to provide a catheter shaft that is easy to pull out of the body and is unlikely to break when pulled out, even when an external force is applied from a blood vessel due to spasm. [Means for solving the problem]

[0006] A catheter shaft according to one embodiment of the present disclosure is a catheter shaft comprising a shaft body with a multi-lumen structure and at least one reinforcing layer embedded in the shaft body, wherein a tensile test is performed on a test specimen obtained from the catheter shaft under test conditions of a chuck distance of 30 mm and a tensile speed of 300 mm / min, where the ratio of the change in the minimum outer diameter after tension to the minimum outer diameter before tension at a specified position of the test specimen is defined as the diameter reduction rate (%), and the ratio of the change in the axial dimension of the catheter shaft after tension to the axial dimension before tension is defined as the elongation rate (%). When the test specimen does not break and the elongation rate reaches 100% in the tensile test, the diameter reduction rate is 5% or more.

[0007] A catheter shaft according to another embodiment of the present disclosure is a catheter shaft comprising a shaft body with a multi-lumen structure and at least one reinforcing layer embedded in the shaft body, wherein a tensile test is conducted on a test specimen obtained from the catheter shaft under test conditions of a chuck distance of 30 mm and a tensile speed of 300 mm / min. When the ratio of the amount of change in the minimum outer diameter after tension to the minimum outer diameter before tension at a specified position of the test specimen is defined as the diameter reduction rate (%), when a tensile load of 90 N begins to be applied to the test specimen in the tensile test, the diameter reduction rate is 20% or more. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a catheter shaft that is easy to pull out of the body and is unlikely to break when pulled out, even when an external force is applied from a blood vessel due to spasm. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1(A) shows the state of the braid before it is stretched and deformed, and FIG. 1(B) is an explanatory diagram showing the state of the braid after it is stretched and deformed. [Diagram 2] 1 is an overall view showing a catheter device according to an embodiment. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4]FIG. 4(A) is a diagram showing an example of a braiding pattern of the braid of the embodiment, and FIG. 4(B) is a diagram showing another example of a braiding pattern. [Diagram 5] FIG. 5(A) is a schematic diagram showing a test piece used in a tensile test, and FIG. 5(B) is a schematic diagram showing the test piece set in a tensile tester. [Figure 6] 1 is a graph showing the relationship between elongation and diameter reduction rate obtained by a tensile test. [Figure 7] 1 is a graph showing the relationship between tensile load and diameter reduction rate obtained by a tensile test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment for carrying out the present disclosure will be described. The same or equivalent components are given the same reference numerals, and duplicated explanations will be omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for the convenience of explanation. The drawings should be viewed according to the orientation of the reference numerals. In this specification, "or" means that at least one of the two or more elements mentioned is true.

[0011] First, the background that led to the invention of the catheter shaft of the present disclosure will be described. Assume a catheter shaft that includes a shaft body with a multi-lumen structure and at least one reinforcing layer embedded in the shaft body. The inventors of the present application have conducted research into how to make such a catheter shaft easier to pull out of the body when an external force is applied from a blood vessel due to spasm.

[0012] The reason for focusing on the multi-lumen structure is that, in the case of a multi-lumen structure, the catheter shaft is more likely to break when the catheter shaft is pulled out after an external force is applied from a blood vessel due to spasm, compared to a single-lumen structure. The reason for this is not entirely clear, but the following is thought to be the reason. In the case of a multi-lumen structure, thinner areas are more likely to occur between the outer circumferential surface of the shaft body and the lumen, or between adjacent lumens, compared to a single-lumen structure. It is thought that the catheter shaft is more likely to break in the case of a multi-lumen structure compared to a single-lumen structure due to stress concentration occurring in these thinner areas.

[0013] In the course of this investigation, the inventors of the present application have newly focused on the ease with which a catheter shaft narrows when pulled in relation to the ease with which a catheter shaft that has been subjected to external force from a blood vessel due to spasm can be pulled out. This is because the catheter shaft can be made easier to pull out by narrowing the catheter shaft at the point where external force is applied from the blood vessel when the catheter shaft is pulled.

[0014] The inventors of the present application discovered the concept of a catheter shaft's diameter reduction rate, which can be measured by a tensile test, as a new index showing the ease with which the catheter shaft can be thinned. When the inventors confirmed the diameter reduction rate that can be achieved by a catheter shaft with a general multi-lumen structure, they found that the maximum diameter reduction rate that can be achieved by this test specimen is usually about 0 to 3%, and does not exceed 5%.

[0015] Therefore, in relation to the problem of making the catheter shaft easy to pull out, the catheter shaft of the present disclosure is required to satisfy at least one of the following first shaft condition or second shaft condition regarding the shaft, taking into consideration the ease of measuring the diameter reduction rate. The first shaft condition is that the diameter reduction rate is 5% or more when the test specimen does not break in the tensile test and the elongation rate (described later) of the test specimen becomes 100%. The second shaft condition is that the diameter reduction rate is 20% when the test specimen does not break in the tensile test and a tensile load of 90 N begins to be applied to the test specimen. The elongation rate of the test specimen here is a value indicating the ease of stretching of the catheter shaft. Each shaft condition is required to satisfy the condition that the diameter reduction rate measured when the standard condition (the elongation rate of the test specimen becomes 100% or the tensile load of 90 N begins to be applied to the test specimen) is equal to or more than the allowable value during the tensile test. This allowable value of the diameter reduction rate is set as a guideline in relation to the problem of making the catheter shaft easy to pull out. By satisfying at least one of the first shaft condition or the second shaft condition, the catheter shaft can be made easier to pull out and less likely to break when pulled out, even when an external force is applied from the blood vessel due to spasm, compared to a case in which this condition is not satisfied.

[0016] The inventors of the present application have also newly discovered that the larger the maximum possible elongation of the test specimen, the more advantageous it tends to be in increasing the maximum possible diameter reduction rate. When the relationship between the diameter reduction rate and the elongation rate of a typical catheter shaft with a multi-lumen structure was confirmed, it was newly discovered that when the above-mentioned maximum diameter reduction rate is about 0 to 3%, the maximum elongation rate is 50% or less and does not exceed 100%. The idea behind increasing the possible elongation rate of this test specimen will be explained.

[0017] 1(A) and 1(B) are diagrams showing the state of the braid 42 constituting the reinforcing layer of the catheter shaft before and after the elongation deformation. In FIG. 1(A), the axial dimension of the mesh 43 of the braid 42 is P, and in FIG. 1(B), the state is shown in which the mesh 43 has been elongated until the axial dimension becomes P'. The inventors of the present application have found that, in order to increase the above-mentioned elongation rate, when the reinforcing layer is composed of the braid 42, it is important to pay attention not only to the elongation of the shaft body but also to the ease of movement of the wires 40A and 40B during the elongation deformation of the braid 42. The ease of movement of the wires 40A and 40B is improved as the frictional force at the intersections between the wires 40A and 40B is smaller or the pitch of the wires 40A and 40B is smaller. The amount of elongation that the resin shaft body itself can be stretched to before it breaks (hereinafter referred to as the "limit elongation amount") is usually much larger than the amount of elongation that the braid 42 can be stretched to before it breaks. However, when braid 42 is embedded in the shaft body, if the mobility of wires 40A, 40B becomes excessively low, a problem occurs in that the elongation deformation of the shaft body is restricted by braid 42 at a timing excessively earlier than the shaft body reaches its limit elongation amount. If the elongation deformation of the shaft body is restricted in this way by braid 42, the elongation deformation amount of the entire test piece becomes insufficient, which is disadvantageous in obtaining a large elongation percentage.

[0018] Here, the inventors of the present application have found that in order to increase the possible elongation rate of the test specimen, it is effective to adjust factors that affect the ease of movement of the wires 40A, 40B when the braid 42 is about to elongate and to appropriately increase the ease of movement of the wires 40A, 40B. By appropriately increasing the ease of movement of the wires 40A, 40B, it is possible to avoid a situation in which the elongation deformation of the shaft body is restricted by the braid 42 at a timing that is too early before the shaft body reaches its limit elongation amount, which is advantageous in obtaining a large elongation rate. The catheter shaft conceived based on this idea will be described in detail below.

[0019] Please refer to Figure 2. In the following, when describing the positional relationship of each component of the catheter device 12, the axial direction, radial direction, and circumferential direction of the catheter shaft 10 will be used, and these will be simply referred to as the "axial direction," the "radial direction," and the "circumferential direction."

[0020] The catheter shaft 10 is used as a part of a catheter device 12. The catheter device 12 of this embodiment is a balloon catheter having a balloon 14 attached to the catheter shaft 10. Specific examples of the catheter device 12 are not particularly limited, and may be used as, for example, an electrode catheter, a delivery catheter, a guiding catheter, a foreign body removal catheter, an imaging catheter, a microcatheter, etc. The catheter shaft 10 is inserted into the body for treatment of a target organ such as a blood vessel. Here, "treatment" refers to an action related to the treatment or examination of a living body. The catheter shaft 10 is inserted into the body, for example, from a peripheral blood vessel in a hand, a foot, etc.

[0021] The catheter device 12 includes, in addition to the catheter shaft 10, a handle 16 that is attached to the proximal end of the catheter shaft 10 and is held by an operator. The catheter device 12 of the present embodiment includes, as an optional component, a balloon 14 that is attached to the distal end of the catheter shaft 10.

[0022] The catheter shaft 10 has flexibility that allows it to be bent. Here, an example is shown in which a bent section 18 is provided midway in the axial direction of the catheter shaft 10. A tip member 20 is attached to 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.

[0023] Please refer to Fig. 3. Fig. 3 shows the entire range in which reinforcing layers 24A, 24B, which will be described later, exist as viewed from the axial direction. In reality, in a cross section perpendicular to the axial direction, wires (described later) that constitute reinforcing layers 24A, 24B exist partially in the range showing reinforcing layers 24A, 24B.

[0024] The catheter shaft 10 includes a shaft body 22 having a multi-lumen structure and at least one reinforcing layer 24A, 24B embedded in the shaft body 22. The multi-lumen structure here refers to a structure in which a plurality of lumens 26A, 26B are formed in the shaft body 22. Here, an example in which the number of lumens 26A, 26B is two is shown, but the number may be three or more. The plurality of lumens 26A, 26B in this embodiment includes a main lumen 26A and a sub-lumen 26B. In this embodiment, in a cross section perpendicular to the axial direction of the catheter shaft 10, the cross-sectional area of ​​the main lumen 26A is larger than the cross-sectional area of ​​the sub-lumen 26B. The relationship between the cross-sectional areas of the lumens is not particularly limited, and the cross-sectional areas of all the lumens may be the same.

[0025] Each of the multiple lumens 26A, 26B is used to pass at least one of a medical device and a fluid. The main lumen 26A in this embodiment is used to pass a medical device. The sub-lumen 26B in this embodiment is used to pass a fluid for expanding the balloon 14. The medical device to be passed through each of the lumens 26A, 26B refers to, for example, a guide wire, a stent graft, a coil, a wiring member, and various catheters such as an electrode catheter, a balloon catheter, and a microcatheter. The wiring member here refers to, for example, a flexible wiring board that is electrically connected to an electric device mounted on the catheter shaft 10. The electric device here is, for example, an ultrasonic transducer used in Intracardiac Echocardiography (ICE). The fluid to be passed through each of the lumens 26A, 26B refers to, for example, a liquid agent such as a contrast agent, a liquid for irrigation (such as physiological saline), and the like, in addition to a fluid for expanding the balloon 14.

[0026] An object to be passed through each lumen 26A, 26B is introduced into the lumens 26A, 26B from outside the body through introduction ports 28A, 28B provided in the handle 16, and is discharged from the lumens 26A, 26B through outlet ports 30A, 30B provided in the catheter shaft 10. Fig. 2 shows a first introduction port 28A and a first outlet port 30A corresponding to the main lumen 26A, and a second introduction port 28B and a second outlet port 30B corresponding to the sub-lumen 26B.

[0027] The shaft body 22 includes at least one resin layer. In the present embodiment, the shaft body 22 includes, as such resin layers, an inner layer 32, an intermediate layer 34 that covers the inner layer 32, and an outer layer 36 that covers the intermediate layer 34. The main lumen 26A is formed by the inner layer 32, and the sub-lumen 26B is formed by the intermediate layer 34.

[0028] The reinforcement layers 24A, 24B are used to reinforce the shaft body 22. The reinforcement layers 24A, 24B in this embodiment include an inner reinforcement layer 24A surrounding the main lumen 26A, and an outer reinforcement layer 24B surrounding the main lumen 26A and the sub-lumen 26B.

[0029] There is no particular limitation on the number of resin layers constituting the shaft body 22 and the number of reinforcing layers embedded in the shaft body 22. There is also no particular limitation on the positions of the reinforcing layers and lumens in the shaft body 22. For example, only one of the inner reinforcing layer 24A and the outer reinforcing layer 24B described above may be present as the reinforcing layer, or a reinforcing layer different from these may be present.

[0030] Please refer to Figures 4(A) and 4(B). Figures 4(A) and 4(B) are cross-sectional views of a part of the braid 42 constituting the reinforcing layer 24A, as viewed 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 tubular and mesh-like shape. The reinforcing layers 24A and 24B may be formed of a coil made of a spiral wire, instead of the braid 42.

[0031] The braid 42 is composed of a plurality of first wires 40A extending toward one circumferential side as it approaches one axial side, and a plurality of second wires 40B extending toward the other circumferential side as it approaches one axial side. The first wires 40A and the second wires 40B intersect. The braid 42 forms a plurality of meshes 43 by the wires 40A, 40B. The meshes 43 are formed as gaps in locations surrounded by the first wires 40A adjacent to each other in the circumferential direction and the second wires 40B adjacent to each other in the circumferential direction, and are rhombic in shape.

[0032] The braid 42 is woven in a pattern in which each of the first wire 40A and the second wire 40B repeats a braiding unit that rises and falls relative to the other wires in the axial direction. Examples of this braiding pattern include a half pattern (two over two under pattern) shown in FIG. 4(A) and a full pattern (one over one under pattern) shown in FIG. 4(B). The half pattern in FIG. 4(A) is a braiding pattern in which the first wire 40A repeats a braiding unit that passes through the radial outside of two second wires 40B and the radial inside of two second wires 40B in order. The full pattern in FIG. 4(B) is a braiding pattern in which the first wire 40A repeats a braiding unit that passes through the radial outside of the second wire 40B and the radial inside of the second wire 40B in order. The number of wire intersections per braid unit is the number of wires (e.g., second wire 40B) that intersect with one wire (e.g., first wire 40A) per braid unit. The number of wire intersections per braid unit in a half pattern is four, and the number of wire intersections per braid unit in a full pattern is two. The braid pattern of braid 42 given here is merely an example, and various other braid patterns may be used.

[0033] Next, a tensile test used to measure the elongation and diameter reduction rate of the catheter shaft 10 described above will be described. See Fig. 5(A). In this tensile test, a test piece 50 obtained by cutting the catheter shaft 10 to an axial dimension of 100 mm is used. A marked line portion 50a is provided on this test piece 50 by marking the central position in the axial direction (axial position 50 mm from the axial end) with a magic marker.

[0034] Prior to the tensile test, the outer diameter of the marked portion 50a of the test piece 50 before tension is measured by a non-contact outer diameter measuring device. At this time, the minimum outer diameter (diameter) in a cross section perpendicular to the axial direction of the marked portion 50a of the test piece 50 is measured. The minimum outer diameter here refers to the minimum value of the measured values ​​obtained when the outer diameter of the marked portion 50a of the test piece 50 is measured over the entire circumference by the outer diameter measuring device.

[0035] See FIG. 5(B). The tensile test is performed so as to satisfy the items listed in the "Conditions" below. For example, a tensile tester, model number EZ Test EZ-LX manufactured by Shimadzu Corporation, is used, and an air chuck, model number PFG-5kNA, is used. Specific examples of the tensile tester and air chuck are not limited as long as they satisfy the following conditions. The test piece 50 pulled in the tensile test may shrink evenly into a circular shape or into a flat shape. (conditions) Use a tensile testing machine with a load cell rated capacity of 5kN. Both ends of the test piece 50 are covered with a silicone tube 52 (inner diameter 3 mm, outer diameter 5 mm) to prevent damage caused by direct contact between the air chuck 54 and the test piece 50 (the silicone tube 52 may protrude from the air chuck 54). The upper and lower ends of the test piece 50 are chucked by a pair of air chucks 54 with a maximum capacity of 5 kN at a chuck pressure of 0.6 MPa so that the silicone tube 52 does not move. Under test conditions of a chuck distance of 30 mm between the pair of air chucks 54 and a pulling speed of 300 mm / min, one of the air chucks 54 is moved to pull the test piece 50.

[0036] This tensile test is terminated when the test piece 50 is pulled until a predetermined test end condition is met. The test end condition here is that the test piece 50 does not break and the elongation rate (described later) of the test piece 50 becomes a specified elongation rate (here, 100%). If the test piece 50 breaks before the test end condition is met, the tensile test is terminated. When the tensile test is completed, the tensile load applied to the test piece 50 is removed, and the test piece 50 is removed from the tensile tester. Thereafter, the diameter reduction rate of the test piece 50, which will be described next, is measured for the test piece 50 subjected to the tensile test. In addition, for the test piece 50 that has been pulled until it reaches a specified elongation rate without breaking, it is determined whether the reinforcing layers 24A and 24B are exposed or not.

[0037] The presence or absence of breakage of the test specimen 50 is visually determined. "The test specimen 50 breaks" means that, for both the shaft body 22 and the reinforcing layers 24A, 24B of the test specimen 50, the portions on both axial sides of the test specimen 50 are no longer connected to each other and are completely separated.

[0038] The axial dimension of the test piece 50 before tension is L0 (mm), the axial dimension after tension is L1 (mm), and the change in the axial dimension after tension is ΔL (=|L1-L0|). This change in the axial dimension ΔL is represented by the amount of movement of one of the air chucks 54 in the tensile test described above. In this case, the elongation percentage (%) of the test piece 50 is the ratio of the change in the axial dimension ΔL after tension to the axial dimension L0 (mm) of the test piece 50 before tension, and is represented by the following formula (1). As can be seen from the following formula (1), this elongation percentage is a value that can be sequentially calculated from the amount of movement (ΔL) of the air chuck 54 during the tensile test. Elongation rate (%) = (ΔL / L0) × 100 (1)

[0039] The minimum outer diameter (diameter) of the test piece 50 at a predetermined position before tension is Φ0 (mm), the minimum outer diameter (diameter) of the test piece 50 after tension is Φ1 (mm), and the amount of change in the minimum outer diameter after tension is ΔΦ (=|Φ0-Φ1|). In this case, the diameter reduction rate (%) of the test piece 50 is the ratio of the amount of change in the minimum outer diameter after tension, ΔΦ, to the minimum outer diameter Φ0 before tension, and is expressed by the following formula (2). The predetermined position here refers to the axial center position of the test piece 50 where the marked line portion 50a is located. Diameter reduction rate (%)=(ΔΦ / Φ0)×100 (2)

[0040] The presence or absence of exposure of the reinforcing layers 24A, 24B is determined by observing the axial range of the marked line portion 50a±10 mm with a microscope at a magnification of 50 times. In this specification, "the reinforcing layers 24A, 24B are exposed to the outside" means that the shaft body 22 of the test piece 50 is partially torn, so that the reinforcing layers 24A, 24B are exposed to the outside space. In order to satisfy the condition that "the reinforcing layers are exposed to the outside", if there are multiple reinforcing layers 24A, 24B, it is sufficient that at least one of the reinforcing layers 24A, 24B is exposed to the outside. In order to satisfy the condition that "the reinforcing layers are 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.

[0041] The diameter reduction rate when the test piece 50 satisfies the above-mentioned standard condition is an index showing the ease of narrowing when the catheter shaft 10 is pulled to which an external force is applied from a blood vessel by spasm. The larger this diameter reduction rate, the easier it is to narrow the catheter shaft 10 in the contracted blood vessel by pulling the catheter shaft 10 to the outside of the body (proximal side) in a state in which an external force is applied from the blood vessel, and the easier it is to pull the catheter shaft 10 out of the blood vessel. From this viewpoint, the catheter shaft 10 is required to have a diameter reduction rate of 5% or more when the elongation rate of the test piece 50 reaches 100% without breaking (when the first standard condition is satisfied). From the same viewpoint, the catheter shaft 10 is preferably provided with a diameter reduction rate of 10% or more, more preferably 15% or more, when the elongation rate of the catheter shaft 10 similarly reaches 100%. The lower limit of the diameter reduction rate permissible for a shaft to which the present invention is applied is specified using a numerical guideline to be larger than the usual numerical value of 0 to 3% for a catheter shaft 10 with a multi-lumen structure. The upper limit of the diameter reduction rate when the test piece 50 does not break and the elongation rate of the test piece 50 becomes 100% is not particularly limited, but in reality, it is 80%.

[0042] Moreover, the catheter shaft 10 is designed such that the test piece 50 does not break and the elongation of the test piece 50 reaches 100%. This makes it possible to make the catheter shaft 10 easy to pull out, while also making it difficult to break when pulled out.

[0043] The catheter shaft 10 is designed such that the reinforcing layers 24A, 24B are not exposed to the outside when the elongation of the test piece 50 reaches 100% in the tensile test as described above. As a result, during the process of pulling out the catheter shaft 10 to which an external force is applied from a blood vessel, the reinforcing layers 24A, 24B are not exposed from the shaft body 22 until the elongation of the test piece 50 reaches 100%. This reduces the risk that the exposed reinforcing layers 24A, 24B will rub against biological tissue.

[0044] The larger the elongation rate that the test piece 50 can assume, the more advantageous it is in terms of increasing the diameter reduction rate that the test piece 50 can assume. From this perspective, the lower limit of the elongation rate that is permissible for a catheter shaft to which the present invention is applied is preferably increased in increments of 100% from 100% elongation. In other words, the lower limit of the elongation rate is preferably 200%, 300%, 400%, and 500%, in that order. The upper limit of the elongation rate is not particularly limited, but in reality it is 1000%. In either case, it is assumed that the test piece 50 is not broken.

[0045] In order to increase the elongation percentage without breaking the test specimen 50, when the braid 42 is used as the reinforcing layers 24A, 24B, it is preferable to select a material for the shaft body 22 that has the elongation percentage required to achieve that elongation percentage, and adjust factors that affect the ease of movement of the wires 40A, 40B when the braid 42 tries to elongate and deform. As described above, the ease of movement of the wires 40A, 40B increases as the frictional force at the intersections between the wires 40A, 40B decreases or the pitch of the wires 40A, 40B decreases.

[0046] The present inventors have newly discovered that factors that affect the ease of movement of the wires 40A, 40B include (1) the cross-sectional shape of the wires 40A, 40B, (2) the number of wires 40A, 40B, (3) the weaving pattern of the braid 42, (4) the surface roughness and friction coefficient of the wires 40A, 40B, and (5) the pitch of the wires 40A, 40B. Of these factors, (1) to (4) are factors related to the frictional force at the intersections between the wires 40A, 40B.

[0047] (1) The cross-sectional shape of the wires 40A, 40B affects the contact area at the intersections of the wires 40A, 40B, and a cross-sectional shape that can reduce the contact area is preferable in order to reduce the frictional force at the intersections. From this perspective, in order to increase the ease of movement of the wires 40A, 40B, it is more advantageous to use a circular cross-sectional shape that reduces the contact area at the intersections, rather than a flat cross-sectional shape that increases the contact area at the intersections.

[0048] (2) The number of wires 40A, 40B (the number of wires constituting wires 40A, 40B) also affects the contact area at the intersections of wires 40A, 40B, and the fewer the number of wires, the better in terms of reducing friction at the intersections. From this perspective, in terms of increasing the ease of movement of wires 40A, 40B, a single wire is more advantageous than a multiple wire.

[0049] (3) The weaving pattern of the braid 42 affects the normal force at the intersection of the wires 40A, 40B, and in order to reduce the frictional force at the intersection, a weaving pattern that has a large number of wire intersections per weaving unit is preferable. From this perspective, in order to increase the ease of movement of the wires 40A, 40B, it is more advantageous to use a weaving pattern for the braid 42 that has a large number of wire intersections (e.g., a half pattern) than to use a weaving pattern that has a small number of wire intersections per weaving unit (e.g., a full pattern).

[0050] In order to reduce the frictional force at the intersections of the wires 40A, 40B, the wires 40A, 40B may be subjected to a surface treatment (4) for reducing either the surface roughness or the coefficient of friction of the wires 40A, 40B.

[0051] In order to increase the ease of movement of the wires 40A, 40B, it is preferable to make the inclination angle of the wires 40A, 40B with respect to the axial direction steeper. From this viewpoint, in order to increase the ease of movement of the wires 40A, 40B, it is more advantageous for the pitch of the wires 40A, 40B in (5) to be narrower than for the pitch to be wider. Here, the pitch refers to the axial dimension P (see FIG. 1) of the mesh 43 of the braid 42.

[0052] In order to adjust the elongation rate without breaking the test specimen, at least any one of the factors (1) to (5) may be adjusted. In other words, it can be said that any one of the factors is adjusted so that the catheter shaft 10 satisfies the above-mentioned elongation rate condition (e.g., the condition of 100% or more).

[0053] When coils are used as the reinforcing layers 24A and 24B, the elongation rate may be adjusted by adjusting the coil pitch (pitch angle), wire diameter, number of strands, material, cross-sectional shape, etc. For example, the elongation rate may be increased by reducing the coil pitch, reducing the wire diameter, or reducing the number of strands so that the wire can easily elongate and deform in the axial direction. In addition, the material and cross-sectional shape may be adjusted to increase the elongation rate so that the wire can easily elongate and deform in the axial direction.

[0054] Examples of the material of the shaft body 22 that has the stretchability to achieve the above-mentioned elongation rate include resins such as PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy fluoride resin), PEBAX (polyether block amide, registered trademark), PA12 (polyamide 12), and TPU (thermoplastic polyurethane). In order to increase the elongation rate, it is preferable to use a material that is easy to stretch as the material of the shaft body 22. Furthermore, the material of the wires 40A and 40B is not particularly limited, but metals such as stainless steel and Ni-Ti alloys may be used. Furthermore, resins may be used as the material of the wires 40A and 40B.

[0055] In adjusting the diameter reduction rate, the elongation rate itself may be adjusted, or factors affecting the elongation rate (ease of elongation of the material of the shaft body 22, factors affecting the ease of movement of the wires 40A, 40B) may be adjusted. For example, in order to increase the diameter reduction rate, the adjustment method adopted to increase the elongation rate described above may be adopted. In addition, in order to increase the diameter reduction rate and the elongation rate without exposing the reinforcing layers 24A, 24B to the outside, each of the following (1) to (3) may be adjusted within the range allowed by the design. (1) is the material of the shaft body 22, (2) is the thickness of the portion of the shaft body 22 that is radially outward from the reinforcing layers 24A, 24B (the outer layer 26 in the embodiment), and (3) is a factor affecting the ease of movement of the wires 40A, 40B. For example, it is preferable to adopt an easily elongated material as the material of the shaft body 22 in (1). In adopting such an easily elongated material, it is preferable to adopt a resin material with low hardness because the lower the hardness of the resin material, the easier it is to elongate. For example, PEBAX with low hardness is more stretchable than PEBAX with high hardness, and is therefore preferred as the material for the shaft body 22. In addition, inorganic substances such as barium sulfate may be added to the material for the shaft body 22 in order to improve contrast and other properties. The more inorganic substances are added, the less stretchable the shaft body 22 becomes. Therefore, when using a material that is easy to stretch, it is preferable to minimize the amount of inorganic substances added or to use a material to which no inorganic substances are added. (2) By increasing the partial thickness of the shaft body 22, it is advantageous to avoid exposure of the reinforcing layers 24A, 24B caused by partial tearing of the shaft body 22. (3) The wires 40A, 40B may be made more mobile by adjusting factors that affect the ease of movement of the wires 40A, 40B. If the wires 40A, 40B were less likely to move when the shaft body 22 elongated, the elongation of the shaft body 22 would be restrained early by the braid 42, as described above, which could lead to partial tearing of the shaft body 22 starting from the contact point between the shaft body 22 and the braid 42. Making the wires 40A, 40B more likely to move helps to avoid a situation in which the elongation of the shaft body 22 is restrained early by the braid 42, and is advantageous in avoiding exposure of the reinforcing layers 24A, 24B due to partial tearing of the shaft body 22.

[0056] The maximum load (N) that can be applied to the test piece 50 during the tensile test until the test piece 50 breaks is preferably 90 N or more. This "maximum load" refers to the maximum tensile load that can be applied to the test piece 50 from the start of pulling the test piece 50 until the test piece 50 breaks. The present inventors have found that when an operator applies a tensile load to the catheter shaft 10 by pulling the catheter shaft in a state in which an external force is applied from a blood vessel, the tensile load is usually less than 90 N. By satisfying the above-mentioned maximum load condition, it is possible to avoid the catheter shaft 10 from breaking as long as the tensile load is within the range of the tensile load that an operator normally applies.

[0057] The amount of tension of the test piece 50 when the test piece 50 is at the maximum load (the amount of change in the axial dimension of the test piece 50 before and after tension) is referred to as the amount of tension at maximum load. At this time, the manner in which the tensile load applied to the test piece 50 changes from when tension on the test piece starts until it reaches the amount of tension at maximum load is not particularly limited. For example, the tensile load applied to the test piece 50 from when tension on the test piece 50 starts until it reaches a predetermined amount of tension (e.g., 3 / 4 of the amount of tension at maximum load) may be less than 90 N, or the tensile load may reach 90 N or more during that time.

[0058] In order to adjust the maximum load that can be applied to the test piece 50 by the tensile test, if the reinforcing layers 24A, 24B are braids 42, the total value of the breaking strength of the wires 40A, 40B may be adjusted. The total value of the breaking strength of the wires 40A, 40B is affected by (1) the cross-sectional area of ​​the wires 40A, 40B, and (2) the number of stitches of the braid 42 (the number of meshes 43 in a cross section perpendicular to the axial direction). In order to increase the breaking strength, it is more advantageous to increase the cross-sectional area of ​​the wires 40A, 40B (1). In order to increase the breaking strength, it is more advantageous to increase the number of stitches (2). The catheter shaft 10 may be configured to achieve the maximum load (90N or more) under the above-mentioned conditions by adjusting either (1) or (2). In addition, if the reinforcing layers 24A, 24B are coils, it is more advantageous to adjust (1) to achieve the maximum load (90N or more) under the above-mentioned conditions.

[0059] The maximum load (N) that can be applied to the test piece 50 in the tensile test preferably satisfies the following condition. The following condition specifies the breaking strength required for 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 condition, the minimum breaking strength required for the catheter shaft 10 by ISO can be ensured. (conditions) For 0.55mm≦Φ0<0.75mm: The maximum load is 3N or more. When 0.75mm≦Φ0<1.15mm: The maximum load is 5N or more. When 1.15mm≦Φ0<1.85mm: The maximum load is 10N or more. When 1.85mm≦Φ0: The maximum load is 15N or more.

[0060] The catheter shaft 10 preferably satisfies the condition that the reinforcing layers 24A, 24B are not exposed to the outside when a tensile load of 90N starts to be applied to the test piece 50 in the above-mentioned tensile test. Here, "when a tensile load of 90N starts to be applied to the test piece 50" means the time when a tensile load of 90N is applied for the first time in the process of increasing the tensile load applied to the test piece 50 in the tensile test. This makes it possible to avoid a situation in which the shaft body 22 is partially torn and the reinforcing layers 24A, 24B are exposed to the outside when the catheter shaft 10 is pulled while 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 surgeon (less than 90N). To satisfy this condition, the adjustment method adopted to increase the diameter reduction rate and elongation rate without exposing the reinforcing layers 24A, 24B to the outside may be used.

[0061] Up to this point, the shaft condition that the catheter shaft 10 should satisfy has been described by taking as an example the first shaft condition described above, in which the diameter reduction rate measured when the test piece 50 does not break in the tensile test and the elongation rate of the test piece 50 reaches 100% is 5% or more. Alternatively, the shaft condition that the catheter shaft 10 should satisfy may be the second shaft condition described above, in which the diameter reduction rate is 20% or more when the test piece 50 is pulled until a tensile load of 90 N begins to be applied in the tensile test. In this case, the tensile test is terminated immediately after the test piece 50 is pulled until a tensile load of 90 N begins to be applied in the tensile test. After this, the tensile load applied to the test piece 50 is removed, and the diameter reduction rate measured for the test piece 50 taken out of the tensile tester should be 20% or more. In satisfying the second shaft condition, it is assumed that the test piece 50 does not break when pulled until a tensile load of 90 N begins to be applied. In this case as well, it is preferable that the reinforcing layers 24A, 24B are not exposed to the outside when a tensile load of 90N starts to be applied to the test piece 50. When a tensile load of 90N starts to be applied in the tensile test, the elongation of the test piece 50 exceeds 100%, and is greater than the diameter reduction rate when the elongation rate becomes 100%. Due to this relationship, the allowable value of the diameter reduction rate (20%) that should be satisfied in the second shaft condition is greater than the allowable value of the diameter reduction rate (5%) that should be satisfied in the first shaft condition.

[0062] Next, a tensile test conducted to confirm the relationship between the diameter reduction rate and the elongation rate will be described. In this tensile test, a test piece 50 under the conditions shown in Table 1 below was used, and the test piece was pulled until a predetermined elongation rate was reached. In Table 1, in addition to the type of test piece, the stretchability of the resin material of the shaft body, the cross-sectional shape of the wire, and the number of strokes are listed for each type. The cross-sectional shapes of the wire are listed in order of the cross-sectional shapes of the outer reinforcing layer 24B and the inner reinforcing layer 24A. Types A and E are examples in which only the pitch of the wire is changed.

[0063] [Table 1]

[0064] The test results are explained below. Table 1 shows the results of the tensile test for each test piece 50, including the minimum outer diameter before tension, the minimum outer diameter after tension, the elongation rate, and the diameter reduction rate, as well as the maximum load, whether the reinforcing layers 24A and 24B were exposed, and whether the test piece 50 broke. The maximum load in Table 1 indicates the maximum load applied from the start of tensioning the test piece 50 until a predetermined elongation rate was reached. No. 9 (type B) and No. 18 (type D) are examples in which the test piece broke before being stretched to a 50% elongation rate from the start of tensioning.

[0065] FIG. 6 is a graph showing the results of the tensile test. Types B and D break when the maximum elongation is less than 50%, and are examples in which the diameter reduction rate is not 5% or more when the test piece does not break and the elongation rate is 100%. In contrast, types A, C, and E are examples in which the diameter reduction rate is 5% or more when the test piece does not break and the elongation rate is 100%. Furthermore, from these comparisons, it can be seen that when the test piece 50 does not break and the elongation rate is 100%, it is advantageous to make the diameter reduction rate 5% or more. Furthermore, from FIG. 6, it can be seen that the larger the elongation rate that the test piece 50 can have without breaking, the more advantageous it tends to be to increase the diameter reduction rate. For example, when comparing type E, in which the elongation rate of the test piece 50 is less than 300%, with types A and C, in which the elongation rate is 300% or more, it can be seen that the latter has a larger diameter reduction rate.

[0066] In addition, from the comparison of types A and E, it can be seen that the narrower the pitch of the wire in the order of E → A, the greater the possible elongation rate and diameter reduction rate. In addition, from the comparison of types A and C, it can be seen that the wire cross-sectional shape is more advantageous than the flat cross-section. Circular cross section It can be seen that the above is advantageous in increasing the possible elongation rate and diameter reduction rate.

[0067] Figure 7 is a graph summarizing the results shown in Table 1 in terms of the relationship between tensile load and diameter reduction rate. Types B and D are examples in which the test piece broke before a tensile load of 90N was applied to it, and the diameter reduction rate was not 20% or more when the tensile load of 90N started to be applied to the test piece. Types A, C, and E are examples in which the diameter reduction rate was 20% or more when the tensile load of 90N started to be applied to the test piece.

[0068] The above embodiments are merely examples. The technical ideas abstracted from these should not be interpreted as being limited to the contents of the embodiments. Many design changes are possible in the contents of the embodiments, such as changes, additions, and deletions of components. In the above-mentioned embodiments, the contents in which such design changes are possible are emphasized by adding the notation "embodiment". However, design changes are also permitted even in contents without such notation. Hatching on the cross sections of the drawings does not limit the material of the hatched object.

[0069] The maximum diameter reduction rate and elongation rate that the test piece 50 can have when the reinforcing layers 24A, 24B are not exposed may be measured according to the following procedure. (1) First, an initial tensile test is performed in which the test piece 50 is pulled until it breaks. In the initial tensile test, the elongation of the test piece 50 when it breaks is measured. (2) Next, a second tensile test is performed using the 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 pulled until the elongation rate is 10% less than the elongation rate measured in the first tensile test. After this, the test piece 50 obtained by this tensile test is judged for the presence or absence of exposure of the reinforcing layer. (3) If the reinforcing layer is exposed in (2), a tensile test is performed in which the specimen is pulled until the elongation reaches the elongation reached in the previous tensile test minus 10%, and the series of steps up to determining whether the reinforcing layer of the test piece 50 obtained by the tensile test is exposed or not is repeated. This series of steps is repeated until a test piece 50 in which the reinforcing layer is not exposed after the tensile test is obtained. (4) In (2) and (3), when a test piece 50 in which the reinforcing layer is not exposed after the tensile test is obtained, measure the diameter reduction rate of the test piece 50. The diameter reduction rate of the test piece 50 thus measured and the elongation rate achieved in the tensile test for the test piece 50 may be used as the maximum diameter reduction rate and elongation rate that the test piece 50 can have in a state in which the reinforcing layer is not exposed. [Explanation of symbols]

[0070] 10...catheter shaft, 12...catheter device, 22...shaft body, 24A, 24B...reinforcing layer, 26A, 26B...lumen, 40A, 40B...wire, 42...braid, 50...test piece.

Claims

1. A shaft body with a multi-lumen structure, at least one reinforcing layer embedded in the shaft body, The reinforcing layer is a braid formed by braiding a plurality of wires into a tubular and mesh-like shape, A tensile test was conducted by pulling a test piece obtained from the catheter shaft under test conditions of a chuck distance of 30 mm and a pulling speed of 300 mm / min. The ratio of the change in the minimum outer diameter after pulling to the minimum outer diameter before pulling at a predetermined position of the test piece was defined as the diameter reduction rate (%), and the ratio of the change in the axial dimension after pulling to the axial dimension of the catheter shaft before pulling was defined as the elongation rate (%). The factors affecting the ease of movement of the wire when the reinforcing layer attempts to elongate and deform, and the material of the shaft body were adjusted so that the diameter reduction rate was 5% or more when the elongation rate of the test piece reached 100% without breaking in the tensile test. A catheter shaft in which one of the factors affecting the ease of movement of the strands is that the braid comprises strands of circular cross section.

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

3. 2. The catheter shaft according to claim 1, wherein the maximum tensile load (N) that can be applied to the test piece before the test piece breaks in the tensile test is 90 N or more.

4. 2. The catheter shaft according to claim 1, wherein the reinforcing layer is not exposed to the outside when a tensile load of 90 N begins to be applied to the test piece in the tensile test.

5. A shaft body with a multi-lumen structure, at least one reinforcing layer embedded in the shaft body, The reinforcing layer is a braid formed by braiding a plurality of wires into a tubular and mesh-like shape, a tensile test was conducted on a test piece obtained from the catheter shaft under test conditions of a chuck distance of 30 mm and a tensile speed of 300 mm / min. When the ratio of the amount of change in the minimum outer diameter after tension to the minimum outer diameter before tension at a predetermined position of the test piece was defined as the diameter reduction rate (%), when a tensile load of 90 N began to be applied to the test piece in the tensile test, the factors influencing the ease of movement of the wires constituting the reinforcing layer when the reinforcing layer attempts to elongate and the material of the shaft body were adjusted so that the diameter reduction rate was 20% or more when A catheter shaft in which one of the factors affecting the ease of movement of the strands is that the braid comprises strands of circular cross section.

6. A catheter device comprising the catheter shaft according to any one of claims 1 to 5.

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