Catheter

Abstract

To provide a catheter that has high insertability in both a hardened living body lumen and a curved living body lumen, and that is easily delivered. This catheter (1) has: a shaft (10) that has a longitudinal direction (x1) and a circumferential direction (z1) around the outer circumference in a cross-section perpendicular to the longitudinal direction (x1), and that is provided with a lumen extending in the longitudinal direction (x1); and a core material (20) that is disposed in the lumen of the shaft (10). The shaft (10) has an outer resin tube (11) and an inner resin tube (12) that is disposed in the lumen of the outer resin tube (11). The shaft (10) has a first region (R1) positioned further to the distal side than the distal end (20d) of the core material (20), and a second region (R2) positioned further to the distal side than the first region (R1). In the first region (R1), the longitudinal component of the molecular orientation of the inner resin tube (12) is greater than the longitudinal component of the molecular orientation of the outer resin tube (11).

Description

catheter

[0001] The present invention relates to a catheter.

[0002] As a minimally invasive treatment for lesions in blood vessels or organs that does not involve open surgery, catheters are widely used to treat lesions such as stenosis and administer contrast agents or drugs into blood vessels, and for other procedures and examinations. Catheters are inserted into internal lumens such as blood vessels in the limbs or groin, or the digestive tract such as the bile duct, and delivered to the lesion site.

[0003] It is known that stenosis in blood vessels, which are the channels through which blood circulates in the body, can lead to various diseases due to stagnation of blood circulation. In particular, stenosis in the coronary arteries that supply blood to the heart can lead to serious diseases such as angina pectoris and myocardial infarction. One method for treating such vascular stenosis is angioplasty (PTA, PTCA, etc.), which dilates the stenotic area using a balloon catheter or stent. Angioplasty is a minimally invasive therapy that does not require open chest surgery, such as bypass surgery. Angioplasty is also used to treat stenosis occurring in shunts used for dialysis.

[0004] In addition, bile duct obstruction due to gallstones, tumors, etc., or obstruction of bile flow within the bile duct can cause bile to stagnate in the bile duct, leading to bacterial infection. Bacterial infection of bile can lead to cholangitis, and if bacteria-containing bile flows through the liver into the bloodstream, it can cause sepsis. In such cases, a procedure to drain bile from the bile duct is required, and a catheter is inserted into the bile duct, and procedures such as percutaneous transhepatic biliary drainage (PTCD) or endoscopic biliary drainage (ERBD) are performed.

[0005] Patent Document 1 describes a balloon catheter capable of transmitting a pushing force transmitted from the proximal side to the distal side. The balloon catheter includes a balloon, a cylindrical outer shaft constituting an expansion lumen for supplying a fluid for expanding the balloon, an orifice control portion having a control hole communicating with the expansion lumen, a core wire having a pressing portion capable of abutting against the control hole of the orifice control portion, an inner shaft having a guidewire lumen therein for inserting a guidewire, a tip guidewire port formed at the distal end of the inner shaft, and a rear guidewire port formed at the proximal end of the inner shaft, and the rear guidewire port is formed in the orifice control portion of the outer shaft.

[0006] Patent Document 2 describes a balloon catheter that can be located or identified during use, which includes a shaft, an inflatable balloon attached to the shaft and having an interior, and at least three radiopaque markings on the interior of the balloon spaced apart along a longitudinal axis of the catheter, wherein a first distance separating a first radiopaque marking from an adjacent second radiopaque marking is different from a second distance separating the second radiopaque marking from an adjacent third radiopaque marking.

[0007] Patent Document 3 describes a balloon catheter that is excellent in pushability and can prevent kinking. The balloon catheter includes an outer shaft, a balloon connected to the distal end of the outer shaft, a hub connected to the proximal end of the outer shaft, an inner tube that is a resin tube forming a guidewire lumen, the proximal end of which opens as a guidewire port on the side surface of the outer shaft and the distal end of which is fixed to the distal end of the balloon and opens at its distal end, and a core wire having a straight portion and a reduced diameter portion, the core wire being fixed to the inner circumferential surface of the outer shaft, the straight portion of the core wire being press-fitted between the inner circumferential surface of the outer shaft and the outer circumferential surface of the inner tube, and the cross section of the outer shaft at the portion where the straight portion of the core wire is press-fitted being deformed into an elliptical shape.

[0008] JP 2015-013207 A JP 2015-527123 A JP 2016-083279 A

[0009] When calcification progresses in blood vessels, the lumen in the body may become hardened. There is a problem in that it is difficult to deliver a catheter through a hardened lumen in the body. Furthermore, if the rigidity of the catheter is increased in order to improve the insertability of the catheter, the catheter becomes difficult to bend, which causes a problem in that the catheter is difficult to insert into a curved lumen in the body. None of the catheters described in Patent Documents 1 to 3 have sufficient insertability through both hardened and curved lumen in the body, and there is room for improvement.

[0010] The present invention has been made in consideration of the above circumstances, and its object is to provide a catheter that has high insertability in both hardened and curved biological lumens and that can be easily delivered.

[0011] The catheter according to an embodiment of the present invention that has solved the above-mentioned problems is as follows: [1] A catheter comprising: a shaft having a longitudinal direction and a circumferential direction along the outer periphery in a cross section perpendicular to the longitudinal direction, and having an inner lumen extending in the longitudinal direction; and a core material disposed in the inner lumen of the shaft, wherein the shaft comprises an outer resin tube and an inner resin tube disposed in the lumen of the outer resin tube, and the shaft has a first region located distal to the distal end of the core material and a second region located distal to the first region, wherein in the first region, a longitudinal component of molecular orientation of the inner resin tube is greater than a longitudinal component of molecular orientation of the outer resin tube. [2] The catheter according to [1], wherein the outer diameter of the outer resin tube in the second region is smaller than the outer diameter of the outer resin tube in the first region. [3] The catheter according to [1] or [2], wherein the longitudinal component of the molecular orientation of the outer resin tube in the second region is greater than the longitudinal component of the molecular orientation of the outer resin tube in the first region. [4] The catheter according to any of [1] to [3], wherein the main direction of molecular orientation of the outer resin tube and the main direction of molecular orientation of the inner resin tube in the second region are the longitudinal direction. [5] The catheter according to any of [1] to [4], wherein the main direction of molecular orientation of the inner resin tube is the longitudinal direction. [6] The catheter according to any of [1] to [5], wherein the longitudinal component of the molecular orientation of the outer resin tube in the second region is greater than the longitudinal component of the molecular orientation of the inner resin tube. [7] The catheter according to any of [1] to [6], wherein the circumferential wall of the outer resin tube has an opening communicating between the outside of the outer resin tube and the lumen of the inner resin tube, and the opening is located proximal to the distal end of the core material. [8] A catheter according to any one of [1] to [7], further comprising a balloon disposed in the distal portion of the outer resin tube.[9] The catheter described in [8], wherein the shaft has a fluid supply tube that is connected to the inner cavity of the balloon and through which fluid is supplied, the fluid supply tube is disposed in the inner cavity of the outer resin tube and outside the inner resin tube, and the cross-sectional shape of the inner cavity of the fluid supply tube in a cross section perpendicular to the longitudinal direction is elliptical.

[0012] According to the catheter, the shaft has a first region located distal to the distal end of the core material and a second region located distal to the first region, and in the first region, the longitudinal component of the molecular orientation of the inner resin tube is greater than the longitudinal component of the molecular orientation of the outer resin tube, thereby increasing the rigidity of the inner resin tube in the first region and increasing the flexibility of the outer resin tube. As a result, it is possible to achieve both the rigidity provided by the inner resin tube and the flexibility provided by the outer resin tube in the first region, thereby improving insertability in both hardened and curved biological lumens and facilitating catheter delivery.

[0013] 6(a) shows a side view of a catheter according to one embodiment of the present invention. FIG. 6(b) shows a longitudinal cross-sectional view of the catheter shown in FIG. 1. FIG. 6(c) shows a III-III cross-sectional view of the catheter shown in FIG. 1. FIG. 6(d) shows a IV-IV cross-sectional view of the catheter shown in FIG. 1. FIG. 6(e) shows a longitudinal cross-sectional view of a core material according to another embodiment of the present invention. FIG. 6(a) shows a schematic diagram of a method for measuring the breaking elongation of an outer resin tube and an inner resin tube, with FIG. 6(a) showing a schematic diagram at the start of tension and FIG. 6(b) showing a schematic diagram at break. FIG. 6(c) shows a cross-sectional view of a modified example of FIG. 3. FIG. 6(d) shows a cross-sectional view of a modified example of FIG. 4. FIG. 6(e) shows a schematic diagram of an evaluation circuit used to evaluate the insertability of a catheter.

[0014] The present invention will be described below based on the embodiments, but the present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the above and below-described purposes, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component symbols may be omitted in each drawing for convenience. In such cases, please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority is given to helping understand the features of the present invention.

[0015] A catheter according to an embodiment of the present invention has a shaft having a longitudinal direction and a circumferential direction along the outer periphery in a cross section perpendicular to the longitudinal direction, and an inner lumen extending in the longitudinal direction, and a core material disposed in the inner lumen of the shaft, wherein the shaft has an outer resin tube and an inner resin tube disposed in the inner lumen of the outer resin tube, and the shaft has a first region located distal to the distal end of the core material and a second region located distal to the first region, and in the first region, the longitudinal component of the molecular orientation of the inner resin tube is greater than the longitudinal component of the molecular orientation of the outer resin tube.

[0016] A catheter according to an embodiment of the present invention will be described below with reference to Figures 1 to 4. Figure 1 is a side view of a catheter according to an embodiment of the present invention, and Figure 2 is a cross-sectional view along the longitudinal direction of the catheter. Figure 3 is a cross-sectional view of the catheter taken along line III-III, which is a cross-sectional view perpendicular to the longitudinal direction on the distal side of the opening. Figure 4 is a cross-sectional view of the catheter taken along line IV-IV, which is a cross-sectional view perpendicular to the longitudinal direction on the proximal side of the opening.

[0017] As shown in Figures 1 and 2, the catheter 1 has a longitudinal direction x1 and a circumferential direction z1 along the outer periphery in a cross section perpendicular to the longitudinal direction x1, and includes a shaft 10 with an inner cavity extending in the longitudinal direction x1, and a core material 20 arranged in the inner cavity of the shaft 10.

[0018] The shaft 10 has a longitudinal direction x1, a radial direction y1 connecting the centroid of the outer edge of the shaft 10 to a point on the outer edge in a cross section perpendicular to the longitudinal direction x1, and a circumferential direction z1 along the outer periphery of the shaft 10 in a cross section perpendicular to the longitudinal direction x1. The radial direction y1 and the circumferential direction z1 are directions perpendicular to the longitudinal direction x1. In this specification, the direction toward the user of the catheter 1 is referred to as the proximal side, and the side opposite the proximal side, i.e., the direction toward the patient, is referred to as the distal side. The direction from the proximal side to the distal side of the shaft 10 is referred to as the longitudinal direction x1.

[0019] Members and parts other than the shaft 10 also have longitudinal, radial, and circumferential directions, which may or may not be the same as the longitudinal direction x1, radial direction y1, and circumferential direction z1 of the shaft 10. However, for ease of understanding, this specification will be described as assuming that all members and parts have the same longitudinal, radial, and circumferential directions as the longitudinal direction x1, radial direction y1, and circumferential direction z1 of the shaft 10.

[0020] The shaft 10 has an inner lumen extending in the longitudinal direction x1, and has a distal end 10d and a proximal end 10p in the longitudinal direction x1.

[0021] The shaft 10 has an outer resin tube 11 and an inner resin tube 12 disposed in the lumen of the outer resin tube 11. That is, the shaft 10 has the outer resin tube 11 having a lumen extending in the longitudinal direction x1, and the inner resin tube 12 disposed in the lumen of the outer resin tube 11 and having a lumen extending in the longitudinal direction x1.

[0022] The outer resin tube 11 has a distal end 11d and a proximal end 11p in the longitudinal direction x1. The outer resin tube 11 may have an opening at at least one of the distal end 11d and the proximal end 11p. When the distal end 11d of the outer resin tube 11 has an opening, the opening at the distal end 11d of the outer resin tube 11 preferably connects the lumen of the outer resin tube 11 to the outside of the outer resin tube 11. When the proximal end 11p of the outer resin tube 11 has an opening, the opening at the proximal end 11p of the outer resin tube 11 preferably connects the lumen of the outer resin tube 11 to the outside of the outer resin tube 11.

[0023] Examples of materials constituting the outer resin tube 11 include synthetic resins such as polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon, polyester resins such as PET, aromatic polyether ketone resins such as PEEK, polyether polyamide resins, polyurethane resins, polyimide resins, fluorine-based resins such as PTFE, PFA, and ETFE, and polyvinyl chloride resins. Among these, the material constituting the outer resin tube 11 is preferably a polyamide resin, and more preferably a polyamide elastomer. Using a polyamide elastomer as the material constituting the outer resin tube 11 provides the outer surface of the outer resin tube 11 with good slipperiness and appropriate rigidity. This allows the catheter 1 to be easily inserted into blood vessels and facilitate delivery.

[0024] The outer resin tube 11 may have a single-layer structure or a multi-layer structure. When the outer resin tube 11 has a multi-layer structure, for example, the outer resin tube 11 may have a structure in which an intermediate layer of resin tubes constituting the outer resin tube 11 is made of a metal braid such as stainless steel, carbon steel, or a nickel-titanium alloy.

[0025] The inner resin tube 12 has a distal end 12d and a proximal end 12p in the longitudinal direction x1. The inner resin tube 12 may have an opening at at least one of the distal end 12d and the proximal end 12p. When the distal end 12d of the inner resin tube 12 has an opening, the opening at the distal end 12d of the inner resin tube 12 preferably connects the lumen of the inner resin tube 12 to the outside of the inner resin tube 12. When the proximal end 12p of the inner resin tube 12 has an opening, the opening at the proximal end 12p of the inner resin tube 12 preferably connects the lumen of the inner resin tube 12 to the outside of the inner resin tube 12.

[0026] Examples of materials constituting the inner resin tube 12 include the synthetic resins listed above as materials constituting the outer resin tube 11. Among these, the material constituting the inner resin tube 12 is preferably a polyamide resin, and more preferably a polyamide elastomer. Using a polyamide elastomer as the material constituting the inner resin tube 12 can increase the slipperiness of the surface of the inner resin tube 12 and further impart appropriate rigidity to the inner resin tube 12. As a result, it becomes easier to insert an object such as a guidewire into the inner resin tube 12 and to insert the catheter 1 into a blood vessel.

[0027] The inner resin tube 12 may have a single-layer structure or a multi-layer structure. When the inner resin tube 12 has a multi-layer structure, it may have a structure in which a plurality of layers made of the synthetic resins listed above as materials for making the outer resin tube 11 are combined. Furthermore, the inner resin tube 12 may have a structure in which an intermediate layer of the resin tube making up the inner resin tube 12 is made of a metal braid such as stainless steel, carbon steel, or a nickel-titanium alloy.

[0028] The material constituting the inner resin tube 12 may be different from, but is preferably the same as, the material constituting the outer resin tube 11. If the material constituting the inner resin tube 12 and the material constituting the outer resin tube 11 are the same, the bonding strength between the outer resin tube 11 and the inner resin tube 12 can be easily increased when the inner resin tube 12 is placed in the lumen of the outer resin tube 11 and the outer resin tube 11 and the inner resin tube 12 are fixed together.

[0029] Methods for joining the outer resin tube 11 and the inner resin tube 12 include, for example, bonding with an adhesive, welding, and attaching a ring-shaped member or the like to the overlapping portion of the outer resin tube 11 and the inner resin tube 12 and crimping them. Among these, it is preferable that the outer resin tube 11 and the inner resin tube 12 are joined by welding. Joining the outer resin tube 11 and the inner resin tube 12 by welding tends to increase the joining strength between the outer resin tube 11 and the inner resin tube 12, and makes it difficult for the joining of the outer resin tube 11 and the inner resin tube 12 to be released.

[0030] 1 , a hub 5 may be provided on the proximal side of the shaft 10. Furthermore, when a fluid is supplied to the lumen of the shaft 10, the hub 5 may be provided with a fluid injection portion 6 that communicates with a flow path for the fluid supplied to the lumen of the shaft 10.

[0031] The shaft 10 and the hub 5 can be joined by, for example, bonding with an adhesive, welding, etc. Among these, it is preferable that the shaft 10 and the hub 5 are joined by adhesive. By joining the shaft 10 and the hub 5 by adhesive, even if the materials constituting the shaft 10 and the hub 5 are different, for example, the shaft 10 is made of a highly flexible material and the hub 5 is made of a highly rigid material, it is easy to increase the bond strength between the shaft 10 and the hub 5, and the bond between the shaft 10 and the hub 5 is less likely to come undone, thereby improving the durability of the catheter 1.

[0032] The core material 20 is disposed in the lumen of the shaft 10. By disposing the core material 20 in the lumen of the shaft 10, the rigidity of the shaft 10 can be increased, and it becomes possible to improve the insertability of the catheter 1. In addition, force applied to the shaft 10 from the proximal side of the catheter 1 can be easily transmitted to the distal side of the shaft 10 through the core material 20, and the operability of the catheter 1 can be improved.

[0033] The core material 20 may have a hollow structure, and is preferably a tube or pipe having a cylindrical structure, a coil formed by spirally winding one or more wires, or a combination thereof. Having the core material 20 having a hollow structure increases the rigidity of the shaft 10 while ensuring appropriate flexibility, making it easier to deliver the catheter 1 to the treatment target site even in a curved internal lumen such as a blood vessel. Alternatively, the core material 20 may have a solid structure such as a wire. Having the core material 20 having a solid structure increases the rigidity of the shaft 10, allowing it to be easily inserted into an internal lumen such as a blood vessel.

[0034] The core material 20 is preferably a linear member of a single wire or a stranded wire. Examples of the core material 20 include metal wires such as stainless steel, carbon steel, and nickel-titanium alloys, as well as wires made of synthetic resins such as polyolefin resins such as polyethylene and polypropylene, polyamide resins such as nylon, polyester resins such as PET, aromatic polyether ketone resins such as PEEK, polyether polyamide resins, polyurethane resins, polyimide resins, fluorine-based resins such as PTFE, PFA, and ETFE, and polyvinyl chloride resins. The core material 20 may also have a structure combining a metal material and a synthetic resin material, such as a braid of metal wires and synthetic resin wires, or a metal wire coated with a synthetic resin. The material constituting the core material 20 is preferably a metal wire, and more preferably stainless steel. Using a metal wire as the core material 20 increases the strength of the core material 20, making it less likely to break or deform even when repeatedly bent.

[0035] The core material 20 is preferably flexible. The flexibility of the core material 20 allows the core material 20 to be deformed to conform to the shape of a lumen in the body, such as a blood vessel, and also makes it easier for the catheter 1 to deform to conform to the shape of a curved lumen in the body. Furthermore, in order to maintain the shape of the core material 20, the core material 20 is preferably elastic.

[0036] In order to make the catheter 1 easier to deform at the distal side of the catheter 1, it is preferable that the core material 20 has a portion in which the rigidity decreases from the proximal side to the distal side, and it is even more preferable that at least a portion of the core material 20 in the longitudinal direction has a continuously decreasing rigidity from the proximal side to the distal side.

[0037] It is preferable that the core material 20 has at least a portion where the outer diameter of the core material 20, i.e., the thickness of the core material 20, tapers from the proximal side to the distal side. By having at least a portion where the thickness of the core material 20 tapers from the proximal side to the distal side, force applied to the shaft 10 from the proximal side of the catheter 1 is more easily transmitted to the distal side of the shaft 10, thereby improving the insertability of the catheter 1. Furthermore, by having a portion where the thickness of the core material 20 tapers, the cross-sectional area occupied by the core material 20 in the lumen of the shaft 10 can be reduced, making it possible to reduce the diameter of the shaft 10 and ensure the width of the lumen of the shaft 10.

[0038] As shown in Figure 2, the core material 20 preferably has a large diameter portion on the proximal side where the core material 20 is thick and a small diameter portion on the distal side where the core material 20 is thin, with a tapered portion between the large diameter portion and the small diameter portion where the core material 20 tapers from the proximal side to the distal side. The core material 20 having a large diameter portion, a small diameter portion, and a tapered portion makes it less likely that the difference in rigidity in the longitudinal direction x1 of the core material 20 will be large. As a result, it is possible to reduce the rigidity step in the shaft 10 and prevent kinking.

[0039] Figure 5 is a cross-sectional view along the longitudinal direction of a core material 20 according to another embodiment. As shown in Figure 5, the core material 20 has a large-diameter portion on the proximal side where the core material 20 is thick, a small-diameter portion on the distal side where the core material 20 is thin, and a transition portion between the large-diameter portion and the small-diameter portion. In the cross-sectional view along the longitudinal direction x1, the transition portion preferably has a tapered shape on one side of the central axis extending in the extension direction of the core material 20, and a configuration in which the other side of the central axis is parallel to the extension direction of the core material 20. In other words, in the cross-sectional view along the longitudinal direction x1, the transition portion of the core material 20 preferably has a so-called one-sided tapered shape. Because the core material 20 has a large-diameter portion, a small-diameter portion, and a transition portion, a force applied to the proximal side of the catheter 1 is easily transmitted to the distal side by the core material 20. Furthermore, since the core material 20 has a transition section in which one side is tapered and the other side is parallel to the extension direction of the core material 20, the volume occupied by the distal end of the core material 20 in the inner cavity of the shaft 10 can be reduced, and space can be secured in the inner cavity of the shaft 10 to place other items such as tubes.

[0040] The cross-sectional shape of the core material 20 can be, for example, a circle, an oval, a polygon, a star, a crescent, a fan, or a combination of these. Note that the oval shape includes an ellipse, an egg, and a rounded rectangle. The cross-sectional shape of the core material 20 refers to the shape of a cross section perpendicular to the longitudinal direction when the core material 20 is in a straight state.

[0041] The proximal end 20p of the core material 20 is preferably located more proximal than the proximal end 11p of the outer resin tube 11. By having the proximal end 20p of the core material 20 located more proximal than the proximal end 11p of the outer resin tube 11, the rigidity of the shaft 10 on the proximal side of the catheter 1 can be increased.

[0042] The proximal end of the core material 20 is preferably fixed to the hub 5. Fixing the proximal end of the core material 20 to the hub 5 increases the fixing strength of the core material 20, making it less likely for the core material 20 to move in the longitudinal direction x1 even when the shaft 10 is curved. Methods for fixing the proximal end of the core material 20 to the hub 5 include, for example, adhesion with an adhesive, fitting, etc.

[0043] The shaft 10 has a first region R1 located distal to the distal end 20d of the core material 20, and a second region R2 located distal to the first region R1.

[0044] In the first region R1, the longitudinal component of the molecular orientation of the inner resin tube 12 is greater than the longitudinal component of the molecular orientation of the outer resin tube 11. That is, in the first region R1, the longitudinal component of the molecular orientation of the resin constituting the inner resin tube 12 is greater than the longitudinal component of the molecular orientation of the resin constituting the outer resin tube 11. In the shaft 10, when the longitudinal component of the molecular orientation of the resin constituting the resin tube is greater, the resin tube tends to become stiffer and harder. Since the longitudinal component of the molecular orientation of the inner resin tube 12 is greater than the longitudinal component of the molecular orientation of the outer resin tube 11 in the first region R1, a highly rigid inner resin tube 12 and a highly flexible outer resin tube 11 are present in the portion of the shaft 10 distal to the portion where the core material 20 is disposed. As a result, the core material 20 increases the rigidity of the shaft 10 proximal to the first region R1, making it easier to transmit force applied from the proximal side to the tip of the shaft 10 even in hard blood vessels with advanced calcification, thereby improving insertability.In the first region R1, however, it is possible to achieve both the rigidity of the inner resin tube 12 and the flexibility of the outer resin tube 11, making it easier to insert the catheter 1 even in curved blood vessels.

[0045] A method for measuring the molecular orientation of the outer resin tube 11 and the inner resin tube 12 will be described below.

[0046] The molecular orientation of the outer resin tube 11 and the inner resin tube 12 can be measured by determining the breaking elongation of the outer resin tube 11 and the inner resin tube 12. As shown in Figures 6(a) and 6(b), both ends of the outer resin tube 11 or the inner resin tube 12 are gripped with the chucks of a tensile tester, and the breaking elongation is measured when the outer resin tube 11 or the inner resin tube 12 is pulled in the longitudinal direction until it breaks. The breaking elongation is measured under conditions of a chuck distance of 25 mm and a pulling speed of 500 mm / min. The breaking elongation can be calculated using the following formula, and is the ratio of the chuck distance L2 at break shown in Figure 6(b) to the chuck distance L1 at the start of pulling shown in Figure 6(a). Breaking elongation = (chuck distance L2 at break - chuck distance L1 at the start of pulling) / chuck distance L1 at the start of pulling

[0047] A smaller breaking elongation indicates a larger longitudinal component of molecular orientation, while a larger breaking elongation indicates a smaller longitudinal component of molecular orientation. In other words, in the first region R1, if the breaking elongation of the inner resin tube 12 is smaller than that of the outer resin tube 11, it can be determined that the longitudinal component of molecular orientation of the inner resin tube 12 is larger than that of the outer resin tube 11. This is thought to be because a larger longitudinal component of molecular orientation increases the strength of the resin in the longitudinal direction, making it more difficult to elongate, and reduces the breaking elongation.

[0048] In the first region R1, the breaking elongation of the outer resin tube 11 is preferably at least 1.1 times, more preferably at least 1.2 times, even more preferably at least 1.3 times, and even more preferably at least 1.5 times, the breaking elongation of the inner resin tube 12. By setting the lower limit of the ratio of the breaking elongation of the outer resin tube 11 to the breaking elongation of the inner resin tube 12 in the first region R1 within the above range, the rigidity of the resin tube in the shaft 10 in the first region R1 is increased and the shaft 10 becomes harder, making it less likely to bend excessively. As a result, force applied from the proximal side is more easily transmitted to the tip of the shaft 10, improving the insertability of the catheter 1. Furthermore, in the first region R1, the breaking elongation of the outer resin tube 11 is preferably at most four times, more preferably at most three times, and even more preferably at most two times the breaking elongation of the inner resin tube 12. By setting the upper limit value of the ratio between the breaking elongation rate of the outer resin tube 11 and the breaking elongation rate of the inner resin tube 12 in the first region R1 within the above range, the shaft 10 becomes more likely to deform and bend to fit the internal lumen of the body, making it easier to improve the flexibility of the catheter 1.

[0049] In order to make the longitudinal component of the molecular orientation of the inner resin tube 12 greater than the longitudinal component of the molecular orientation of the outer resin tube 11 in the first region R1, for example, stretching may be performed on the inner resin tube 12 at least in the portion that will become the first region R1, while not stretching the outer resin tube 11, or manufacturing the inner resin tube 12 using a material or manufacturing method that makes it easier for the molecular orientation to be aligned longitudinally than the outer resin tube 11 in at least the portion that will become the first region R1.

[0050] It is preferable that at least a portion of the outer resin tube 11 and at least a portion of the inner resin tube 12 have been subjected to a stretching process. It is more preferable that the entire outer resin tube 11 and the entire inner resin tube 12 have been subjected to a stretching process. By subjecting the outer resin tube 11 and the inner resin tube 12 to a stretching process, the physical properties such as tensile strength and elongation of the outer resin tube 11 and the inner resin tube 12 tend to be uniform.

[0051] The outer diameter of the outer resin tube 11 in the second region R2 is preferably smaller than the outer diameter of the outer resin tube 11 in the first region R1. Specifically, the average outer diameter of the outer resin tube 11 in the second region R2 is preferably smaller than the average outer diameter of the outer resin tube 11 in the first region R1. By making the outer diameter of the outer resin tube 11 in the second region R2 smaller than the outer diameter of the outer resin tube 11 in the first region R1, the rigidity of the outer resin tube 11 in the first region R1 is increased, making it easier to transmit a force applied from the proximal side to the distal end.

[0052] The outer diameter of the outer resin tube 11 in the first region R1 is preferably at least 1.05 times, more preferably at least 1.10 times, even more preferably at least 1.15 times, and even more preferably at least 1.20 times, the outer diameter of the outer resin tube 11 in the second region R2. By setting the lower limit of the ratio of the outer diameters of the outer resin tube 11 in the first region R1 to the second region R2 within the above range, the outer resin tube 11 is less likely to deform in the first region R1. This facilitates transmission of force applied from the proximal side of the catheter 1 to the tip of the catheter 1 through the outer resin tube 11, thereby improving the insertability of the catheter 1. Furthermore, the outer diameter of the outer resin tube 11 in the first region R1 is preferably at most 3.0 times, more preferably at most 2.5 times, and even more preferably at most 2.0 times the outer diameter of the outer resin tube 11 in the second region R2. By setting the upper limit value of the ratio of the outer diameter of the outer resin tube 11 in the first region R1 to the second region R2 within the above range, the outer diameter of the outer resin tube 11 is less likely to become excessively large in the first region R1, making it easier to improve the flexibility and minimal invasiveness of the catheter 1.

[0053] The length LR1 of the first region R1 in the longitudinal direction x1 is preferably longer than the length LR2 of the second region R2 in the longitudinal direction x1. By making the length LR1 of the first region R1 longer than the length LR2 of the second region R2, it becomes easier to ensure the length of the portion of the shaft 10 that is highly rigid due to the inner resin tube 12 and highly flexible due to the outer resin tube 11. As a result, the catheter 1 can be easily bent along and inserted into a curved lumen in a living body.

[0054] The length LR1 of the first region R1 in the longitudinal direction x1 is preferably at least 1.1 times, more preferably at least 1.3 times, even more preferably at least 1.5 times, and even more preferably at least 2.0 times the length LR2 of the second region R2 in the longitudinal direction x1. By setting the lower limit of the ratio of the length LR1 of the first region R1 to the length LR2 of the second region R2 within the above range, the length in the longitudinal direction x1 of the portion where rigidity is increased by the inner resin tube 12 and flexibility is increased by the outer resin tube 11 is likely to be sufficient, thereby improving the insertability of the catheter 1. Furthermore, the length LR1 of the first region R1 in the longitudinal direction x1 is preferably at most 15 times, more preferably at most 10 times, even more preferably at most 8 times, and even more preferably at most 6 times the length LR2 of the second region R2 in the longitudinal direction x1. By setting the lower limit of the ratio between the length LR1 of the first region R1 and the length LR2 of the second region R2 within the above range, the proportion of the second region R2 in which the outer diameter of the outer resin tube 11 is small in the distal part of the shaft 10 can be increased, thereby improving the minimal invasiveness and insertability of the catheter 1.

[0055] The longitudinal component of the molecular orientation of the outer resin tube 11 in the second region R2 is preferably greater than the longitudinal component of the molecular orientation of the outer resin tube 11 in the first region R1. That is, for the resin constituting the outer resin tube 11, the longitudinal component of the molecular orientation in the second region R2 is preferably greater than the longitudinal component of the molecular orientation in the first region R1. By making the longitudinal component of the molecular orientation of the outer resin tube 11 in the second region R2 greater than the longitudinal component of the molecular orientation of the outer resin tube 11 in the first region R1, the rigidity of the outer resin tube 11 can be increased in the second region R2, which is located distal to the first region R1. As a result, force applied from the proximal side of the catheter 1 is easily transmitted to the tip of the shaft 10, resulting in a catheter 1 with good insertability.

[0056] The fact that the longitudinal component of the molecular orientation of the outer resin tube 11 in the second region R2 is greater than the longitudinal component of the molecular orientation of the outer resin tube 11 in the first region R1 means that the breaking elongation of the outer resin tube 11 in the first region R1 is greater than the breaking elongation of the outer resin tube 11 in the second region R2. The breaking elongation of the outer resin tube 11 in the first region R1 is preferably 1.5 times or more, more preferably 3.0 times or more, even more preferably 4.5 times or more, and even more preferably 6.0 times or more, of the breaking elongation of the outer resin tube 11 in the second region R2. By setting the lower limit of the ratio of the breaking elongation of the outer resin tube 11 in the first region R1 to the second region R2 within the above range, the rigidity of the outer resin tube 11 is increased, making it harder and less likely to bend excessively. This makes it easier for force applied from the proximal side to be transmitted to the tip of the shaft 10, thereby improving the insertability of the catheter 1. Furthermore, the breaking elongation of the outer resin tube 11 is prevented from becoming excessively large, which facilitates improving the flexibility and minimal invasiveness of the catheter 1. The breaking elongation of the outer resin tube 11 in the first region R1 is preferably 15 times or less, more preferably 12 times or less, even more preferably 10 times or less, and even more preferably 8 times or less than the breaking elongation of the outer resin tube 11 in the second region R2. By setting the upper limit of the ratio of the breaking elongation of the outer resin tube 11 in the first region R1 to the second region R2 within the above range, the breaking elongation of the outer resin tube 11 is prevented from becoming excessively large, the rigidity difference in the catheter 1 is reduced, the shaft 10 becomes easier to bend in accordance with the body lumen, and the flexibility and minimal invasiveness of the catheter 1 are facilitated.

[0057] In the second region R2, the main molecular orientation direction of the outer resin tube 11 and the main molecular orientation direction of the inner resin tube 12 are preferably the longitudinal direction x1. That is, in the second region R2, the main molecular orientation direction of the resin constituting the outer resin tube 11 is preferably the longitudinal direction x1, and the main molecular orientation direction of the resin constituting the inner resin tube 12 is preferably the longitudinal direction x1. In the second region R2, the main molecular orientation direction of the outer resin tube 11 and the main molecular orientation direction of the inner resin tube 12 are preferably the longitudinal direction x1, thereby increasing the rigidity of the shaft 10 in the second region R2. As a result, force applied to the shaft 10 from the proximal side of the catheter 1 is more easily transmitted to the tip of the shaft 10, facilitating insertion of the catheter 1.

[0058] The main molecular orientation direction of the inner resin tube 12 is preferably the longitudinal direction x1. In other words, the main orientation direction of the resin constituting the inner resin tube 12 is preferably the longitudinal direction x1. When the main molecular orientation direction of the inner resin tube 12 is the longitudinal direction x1, the rigidity of the entire inner resin tube 12 is increased. Therefore, the rigidity of the shaft 10 can be increased by the inner resin tube 12, and the insertability of the catheter 1 can be improved.

[0059] The main orientation direction of the molecules of the outer resin tube 11 in the first region R1 may be the longitudinal direction x1 or the circumferential direction z1. When the main orientation direction of the molecules of the outer resin tube 11 in the first region R1 is the longitudinal direction x1, the rigidity of the outer resin tube 11 in the longitudinal direction x1 is increased, thereby improving the insertability of the catheter 1. Furthermore, when the main orientation direction of the molecules of the outer resin tube 11 in the first region R1 is the circumferential direction z1, the rigidity of the outer resin tube 11 in the circumferential direction z1 is increased, making it easier to prevent buckling, in which the outer resin tube 11 is crushed in the radial direction y1 while bending along a lumen in the body.

[0060] In the second region R2, the longitudinal component of the molecular orientation of the outer resin tube 11 is preferably greater than the longitudinal component of the molecular orientation of the inner resin tube 12. That is, in the second region R2, the breaking elongation of the inner resin tube 12 is preferably greater than the breaking elongation of the outer resin tube 11. In the second region R2, the longitudinal component of the molecular orientation of the outer resin tube 11 is greater than the longitudinal component of the molecular orientation of the inner resin tube 12, thereby increasing the rigidity of the shaft 10 in the second region R2. As a result, force applied to the shaft 10 from the proximal side of the catheter 1 is more easily transmitted to the tip of the shaft 10, facilitating insertion of the catheter 1.

[0061] In the second region R2, the breaking elongation of the inner resin tube 12 is preferably at least 1.5 times, more preferably at least 2.0 times, and even more preferably at least 2.5 times, the breaking elongation of the outer resin tube 11. By setting the lower limit of the ratio of the breaking elongation of the inner resin tube 12 to the breaking elongation of the outer resin tube 11 in the second region R2 within the above range, the rigidity of the shaft 10 in the second region R2 is increased, making it harder and less likely to bend excessively. As a result, force applied from the proximal side is more easily transmitted to the tip of the shaft 10, which makes it easier to improve the insertability of the catheter 1. Furthermore, in the second region R2, the breaking elongation of the inner resin tube 12 is preferably at most 6 times, more preferably at most 5 times, and even more preferably at most 4 times the breaking elongation of the outer resin tube 11. By setting the upper limit value of the ratio between the breaking elongation rate of the inner resin tube 12 and the breaking elongation rate of the outer resin tube 11 in the second region R2 to the above range, the rigidity difference of the shaft 10 in the second region R2 is reduced, making it easier for the shaft 10 to deform to fit the internal lumen of the body, and making it easier to improve the flexibility and minimal invasiveness of the catheter 1.

[0062] 1 and 2 show a so-called rapid exchange type catheter 1 having an opening 13 that is a guidewire port midway from the distal side to the proximal side of the shaft 10, and a guidewire insertion passage from the opening 13 to the distal side of the shaft 10. In the case of a rapid exchange type, the outer resin tube 11 preferably has a distal tube 11a and a proximal tube 11b, but the distal tube 11a and the proximal tube 11b may be separate members. When the distal tube 11a and the proximal tube 11b are separate members, the proximal tube 11b may be made of resin or metal.

[0063] Alternatively, although not shown, the present invention can also be applied to a so-called over-the-wire type catheter 1 having a guide wire passage extending from the distal side to the proximal side of the shaft 10 .

[0064] In the case of a rapid exchange type catheter 1, it is preferable that an appropriate coating be applied to the outer wall of at least one of the distal tube 11 a and the proximal tube 11 b, and it is more preferable that a coating be applied to the outer wall of both the distal tube 11 a and the proximal tube 11 b. In the case of an over-the-wire type catheter 1, it is preferable that an appropriate coating be applied to the outer wall of the outer resin tube 11.

[0065] The coating can be a hydrophilic coating or a hydrophobic coating depending on the purpose, and can be applied by immersing the shaft 10 in a hydrophilic or hydrophobic coating agent, by applying a hydrophilic or hydrophobic coating agent to the outer wall of the shaft 10, or by covering the outer wall of the shaft 10 with a hydrophilic or hydrophobic coating agent. The coating agent may contain drugs or additives.

[0066] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, methyl vinyl ether maleic anhydride copolymer, and hydrophilic coating agents made from any combination thereof.

[0067] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), silicone oil, hydrophobic urethane resin, carbon coat, diamond coat, diamond-like carbon (DLC) coat, ceramic coat, and substances terminated with alkyl groups or perfluoroalkyl groups and having low surface free energy.

[0068] An opening 13 is provided in the peripheral wall of the outer resin tube 11, connecting the outside of the outer resin tube 11 with the lumen of the inner resin tube 12, and the opening 13 is preferably located proximal to the distal end 20d of the core material 20. By positioning the opening 13 proximal to the distal end 20d of the core material 20, the core material 20 can increase the rigidity near the opening 13. Therefore, when an article or fluid is fed into the lumen of the inner resin tube 12 through the opening 13, it is easy to insert the article or fluid into the opening 13. The inner resin tube 12 is a guidewire tube for inserting a guidewire, and the opening 13 is preferably a guidewire port serving as an insertion port for the guidewire.

[0069] The catheter 1 preferably has a treatment section disposed at the distal portion of the outer resin tube 11. The treatment section is used to treat a target site such as a lesion in a lumen within the body. Examples of the treatment section include an expansion member 30 such as a balloon, stent, or basket, electrodes for measuring intracardiac potentials or for passing high-frequency current, and a drug holding section for releasing drugs.

[0070] The catheter 1 preferably further includes a balloon 31 disposed in the distal portion of the outer resin tube 11. In other words, the catheter 1 is preferably a balloon catheter having the balloon 31 that is the expansion member 30.

[0071] The balloon 31 preferably has a straight tube section 34, a proximal tapered section 33 located proximally of the straight tube section 34, and a distal tapered section 35 located distally of the straight tube section 34. The balloon 31 may further have a proximal sleeve section 32 located proximally of the proximal tapered section 33 and a distal sleeve section 36 located distally of the distal tapered section 35.

[0072] The balloon 31 is preferably made of a resin, and more preferably made of a thermoplastic resin, since the balloon 31 is made of a resin, it becomes easy to manufacture the balloon 31 by molding.

[0073] Examples of resins that can be used to form the balloon 31 include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester resins such as polyethylene terephthalate and polyester elastomer; polyurethane resins such as polyurethane and polyurethane elastomer; polyamide resins such as polyphenylene sulfide resin, polyamide and polyamide elastomer; fluorine-based resins; silicone resins; and natural rubbers such as latex rubber. These may be used alone or in combination. Among these, polyamide resins, polyester resins, and polyurethane resins are preferred for use as the resin forming the balloon 31. In particular, elastomer resins are preferred for use as the resin forming the balloon 31 from the viewpoints of thinning and flexibility of the balloon 31. For example, among polyamide resins, nylon 12 and nylon 11 are preferred materials for forming the balloon 31. Nylon 12 is preferred for use as the resin forming the balloon 31 because of its relatively easy moldability during blow molding. Furthermore, polyamide elastomers such as polyether ester amide elastomers and polyamide ether elastomers are preferred for use as the resin forming the balloon 31 from the viewpoints of thinning and flexibility of the balloon 31. Among these, polyether ester amide elastomer is preferably used as the resin constituting the balloon 31 because it has high yield strength and the dimensional stability of the balloon 31 is good.

[0074] When the catheter 1 has a balloon 31, the catheter 1 is configured so that fluid is supplied to the lumen of the balloon 31 through the shaft 10, and the inflation and deflation of the balloon 31 can be controlled using an indeflator (a balloon pressurizer / depressurizer). The fluid may be a pressurized fluid pressurized by a pump or the like. Hereinafter, the fluid supplied to the lumen of the balloon 31 may be referred to as a "balloon inflation fluid."

[0075] When the catheter 1 is an over-the-wire balloon catheter, it is preferable that the inflation lumen and the guidewire lumen extend to the hub 5 located on the proximal side, and that the proximal openings of each lumen are provided in the bifurcated hub 5.

[0076] When the catheter 1 has a balloon 31, it is preferable that a tip member (not shown) is provided at the distal end of the catheter 1. The tip member may be provided at the distal end of the balloon catheter as a separate member from the inner resin tube 12 and connected to the distal end of the balloon 31, or the inner resin tube 12 may extend distally beyond the distal end of the balloon 31, so that the distal end of the inner resin tube 12 functions as the tip member.

[0077] A radiopaque marker 40 may be disposed inside the balloon 31 at a portion of the inner resin tube 12 where the balloon 31 is located in the longitudinal direction x1 so that the position of the balloon 31 can be confirmed under X-ray fluoroscopy. Examples of the location where the radiopaque marker 40 is disposed include positions corresponding to both ends of the straight tube portion 34 of the balloon 31 and a position corresponding to the center of the straight tube portion 34 of the balloon 31. In particular, the radiopaque marker 40 is preferably disposed at positions corresponding to both ends of the straight tube portion 34 of the balloon 31.

[0078] The shape of the radiopaque marker 40 is preferably tubular, and examples of such shapes include a cylindrical shape, a polygonal cylindrical shape, a C-shaped cross section with a notch in the tube, a coil shape with a wound wire, etc. The radiopaque marker 40 can be made of a radiopaque substance such as lead, barium, iodine, tungsten, gold, platinum, iridium, stainless steel, titanium, or a cobalt-chromium alloy.

[0079] In order to confirm the length to which the catheter 1 has been inserted into the body cavity, a position marker 60 may be provided on the shaft 10. Methods for providing the position marker 60 on the shaft 10 include, for example, placing a member serving as a marker on the outer resin tube 11 or the inner resin tube 12, partially coloring the outer surface of the outer resin tube 11 or the inner resin tube 12, or partially peeling off a coating applied to the outer surface of the outer resin tube 11 or the inner resin tube 12. The number of position markers 60 provided on the shaft 10 may be one or more.

[0080] Fig. 7 is a modified example of Fig. 3 and is a cross-sectional view perpendicular to the longitudinal direction x1 on the distal side of the opening 13 of the catheter 1. Fig. 8 is a modified example of Fig. 4 and is a cross-sectional view perpendicular to the longitudinal direction x1 on the proximal side of the opening 13 of the catheter 1.

[0081] As shown in Figures 2 to 4, the shaft 10 has a gap between the outer surface of the inner resin tube 12 and the inner surface of the outer resin tube 11, and balloon inflation fluid may be supplied to the inner cavity of the balloon 31 through the space between the outer surface of the inner resin tube 12 and the inner surface of the outer resin tube 11. However, as shown in Figures 7 and 8, it is preferable that the shaft 10 has a fluid supply tube 14 that communicates with the inner cavity of the balloon 31 and through which balloon inflation fluid is supplied.

[0082] 7 and 8, the shaft 10 has a fluid supply tube 14 that communicates with the lumen of the balloon 31 and through which fluid is supplied, and the fluid supply tube 14 is preferably disposed within the lumen of the outer resin tube 11 and outside the inner resin tube 12. By having the fluid supply tube 14, the shaft 10 is less likely to be damaged when balloon inflation fluid is fed into the lumen of the balloon 31, and the durability of the catheter 1 can be increased.

[0083] When the shaft 10 has the fluid supply tube 14, it is preferable that there be no gaps between the outer surfaces of the inner resin tube 12 and the fluid supply tube 14 and the inner surface of the outer resin tube 11. In other words, it is preferable that there be no gaps between the outer surface of the inner resin tube 12 and the inner surface of the outer resin tube 11, and that there be no gaps between the outer surface of the fluid supply tube 14 and the inner surface of the outer resin tube 11. By not having gaps between the outer surfaces of the inner resin tube 12 and the fluid supply tube 14 and the inner surface of the outer resin tube 11, the rigidity of the shaft 10 is increased, making it easier to improve the insertability of the shaft 10.

[0084] To configure the shaft 10 so that there are no gaps between the outer surface of the inner resin tube 12 and the outer surface of the fluid supply tube 14 and the inner surface of the outer resin tube 11, for example, the outer resin tube 11 can be welded while the inner resin tube 12 and the fluid supply tube 14 are placed in the inner cavity of the outer resin tube 11, or the inner resin tube 12 and the fluid supply tube 14 can be placed in the inner cavity of the outer resin tube 11 and adhesive can be poured into the gaps between the outer surface of the inner resin tube 12 and the outer surface of the fluid supply tube 14 and the inner surface of the outer resin tube 11.

[0085] 7 and 8 , the cross-sectional shape of the lumen of the fluid supply tube 14 in a cross section perpendicular to the longitudinal direction x1 is preferably elliptical. By making the cross-sectional shape of the lumen of the fluid supply tube 14 elliptical, the cross-sectional area of ​​the lumen of the fluid supply tube 14 in the lumen of the outer resin tube 11 is increased, and it is also easier to ensure the wall thickness of the shaft 10 near the fluid supply tube 14. As a result, the pressure resistance of the shaft 10 can be improved, allowing a large amount of fluid to be sent to the balloon 31, and the balloon 31 can be rapidly inflated and deflated, thereby shortening the procedure time.

[0086] When the cross-sectional shape of the lumen of the fluid supply tube 14 in a cross section perpendicular to the longitudinal direction x1 is elliptical, the length of the major axis of the cross-sectional shape of the lumen of the fluid supply tube 14 is preferably 1.2 times or more, more preferably 1.5 times or more, and even more preferably 2.0 times or more, the length of the minor axis of the cross-sectional shape of the lumen of the fluid supply tube 14. By setting the lower limit of the ratio of the major axis to the minor axis of the cross-sectional shape of the lumen of the fluid supply tube 14 within the above range, it becomes easier to ensure the wall thickness of the shaft 10 while ensuring the size of the lumen of the fluid supply tube 14. Furthermore, the length of the major axis of the cross-sectional shape of the lumen of the fluid supply tube 14 is preferably 7 times or less, more preferably 5 times or less, and even more preferably 3 times or less, the length of the minor axis of the cross-sectional shape of the lumen of the fluid supply tube 14. By setting the upper limit of the ratio of the major axis length to the minor axis length in the cross-sectional shape of the lumen of the fluid supply tube 14 within the above range, it is possible to easily increase the cross-sectional area of ​​the lumen of the fluid supply tube 14 without excessively increasing the outer diameter of the outer resin tube 11.

[0087] This application claims the benefit of priority based on Japanese Patent Application No. 2023-142514, filed on September 1, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-142514, filed on September 1, 2023, are incorporated herein by reference.

[0088] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and modifications can be made within the scope of the above and below-described aims, and all such modifications are included in the technical scope of the present invention.

[0089] (Measurement of molecular orientation) Three test pieces, each 50 mm long, were cut out from the outer resin tube and the inner resin tube. For each test piece, both ends of the test piece were fixed with chucks using a universal testing machine (Strograph E3-L, manufactured by Toyo Seiki Seisaku-Sho, Ltd.), and the test piece was pulled at a chuck distance of 25 mm and a tensile speed of 500 mm / min. The chuck distance at break was measured, and the breaking elongation was calculated using the following formula: Breaking elongation = (chuck distance at break - chuck distance at start of tension) / chuck distance at start of tension

[0090] (Evaluation of Insertability) Figure 9 is a schematic diagram of an evaluation circuit used to evaluate the insertability of a catheter. The insertability was evaluated in warm water at approximately 37°C by measuring the pushing load applied to the proximal side of the catheter when the second region of the catheter passed through a branching section at an angle of approximately 135 degrees in the evaluation circuit, which had a cylindrical circuit with an inner diameter of approximately 4 mm as shown in Figure 9. In Figure 9, the insertion direction of the catheter into the evaluation circuit is indicated by a dashed arrow, and the force for pushing the catheter is indicated by a hollow arrow.

[0091] Example 1: An outer resin tube was produced by extrusion molding using a polyamide elastomer and then stretching, with the first region having an outer diameter of 1.3 mm and an inner diameter of 1.0 mm, and the second region having an outer diameter of 1.1 mm and an inner diameter of 1.0 mm. Furthermore, an inner resin tube was produced by extrusion molding using a polyamide elastomer for the outer layer and a polyethylene for the inner layer, with the extrusion molding being further stretched, with the inner resin tube having an outer diameter of 0.7 mm and an inner diameter of 0.5 mm.

[0092] Catheters were fabricated using the obtained outer resin tube and inner resin tube, and their insertability was evaluated. Furthermore, the molecular orientations of the obtained outer resin tube and inner resin tube in the first and second regions were measured. The results are shown in Table 1.

[0093] [Example 2] An outer resin tube and an inner resin tube were prepared in the same manner as in Example 1, except that the outer resin tube was stretched to produce an outer resin tube with an outer diameter of 1.3 mm and an inner diameter of 1.1 mm in the first and second regions. Catheters were fabricated using the obtained outer resin tube and inner resin tube, and insertability was evaluated. In addition, the molecular orientation in each of the first and second regions was measured. The results are shown in Table 1.

[0094] Example 3: The outer resin tube and the inner resin tube were fabricated in the same manner as in Example 1, except that the outer resin tube was stretched to produce an outer resin tube with an outer diameter of 1.5 mm and an inner diameter of 1.3 mm in the first and second regions, and the inner resin tube was stretched to produce an inner resin tube with an outer diameter of 1.0 mm and an inner diameter of 0.6 mm in the first and second regions. Catheters were fabricated using the resulting outer resin tube and inner resin tube, and insertability was evaluated. The molecular orientation in each of the first and second regions was also measured. The results are shown in Table 1.

[0095] [Example 4] An outer resin tube and an inner resin tube were prepared in the same manner as in Example 1, except that the outer resin tube was stretched to produce an outer resin tube with an outer diameter of 1.3 mm and an inner diameter of 1.0 mm in the first and second regions. Catheters were fabricated using the obtained outer resin tube and inner resin tube, and insertability was evaluated. In addition, the molecular orientation in each of the first and second regions was measured. The results are shown in Table 1.

[0096] Comparative Example 1: An outer resin tube having an outer diameter of 1.3 mm and an inner diameter of 1.0 mm was produced by extrusion molding using a polyamide elastomer. An inner resin tube having an outer diameter of 0.6 mm and an inner diameter of 0.5 mm was also produced by extrusion molding using a polyamide elastomer for the outer layer and a polyethylene for the inner layer. The outer and inner resin tubes were not subjected to stretching.

[0097] Catheters were fabricated using the obtained outer resin tube and inner resin tube, and their insertability was evaluated. Furthermore, the molecular orientations of the obtained outer resin tube and inner resin tube in the first and second regions were measured. The results are shown in Table 1.

[0098]

[0099] As shown in Table 1, in the catheters of Examples 1 to 4, the longitudinal component of the molecular orientation of the inner resin tube was greater than the longitudinal component of the molecular orientation of the outer resin tube in the first region. It was confirmed that the indentation load applied to the proximal side of the catheter when passing through the branched portion of the evaluation circuit was smaller in Examples 2 to 4 than in Comparative Example 1, and the indentation load in Example 1 was even smaller. In other words, the catheters of Examples 1 to 4 had superior catheter insertability performance compared to Comparative Example 1.

[0100] 1: Catheter 5: Hub 6: Fluid injection section 10: Shaft 10d: Distal end of shaft 10p: Proximal end of shaft 11: Outer resin tube 11d: Distal end of outer resin tube 11p: Proximal end of outer resin tube 11a: Distal tube 11b: Proximal tube 12: Inner resin tube 12d: Distal end of inner resin tube 12p: Proximal end of inner resin tube 13: Opening 14: Fluid supply tube 20: Core material 20d: Distal end of core material 20p: Proximal end of core material 30: Expansion member 31: Balloon 32: Proximal sleeve portion 33: Proximal tapered portion 34: Straight tube portion 35: Distal tapered portion 36: Distal sleeve portion 40: Radiopaque marker 60: Position marker R1: First region R2: Second region L1: Distance between chucks at the start of tension L2: Distance between chucks at break LR1: Length of first region LR2: Length of second region

Claims

1. A catheter comprising: a shaft having a longitudinal direction and a circumferential direction along the outer periphery in a cross section perpendicular to the longitudinal direction, and having an inner cavity extending in the longitudinal direction; and a core material disposed in the inner cavity of the shaft, wherein the shaft has an outer resin tube and an inner resin tube disposed in the inner cavity of the outer resin tube, wherein the shaft has a first region located distal to the distal end of the core material and a second region located distal to the first region, wherein in the first region, the longitudinal component of the molecular orientation of the inner resin tube is greater than the longitudinal component of the molecular orientation of the outer resin tube.

2. The catheter according to claim 1, wherein the outer diameter of the outer resin tube in the second region is smaller than the outer diameter of the outer resin tube in the first region.

3. The catheter according to claim 1, wherein the longitudinal component of the molecular orientation of the outer resin tube in the second region is greater than the longitudinal component of the molecular orientation of the outer resin tube in the first region.

4. A catheter according to claim 1, wherein in said second region, the main orientation direction of the molecules of said outer resin tube and the main orientation direction of the molecules of said inner resin tube are the longitudinal direction.

5. The catheter according to claim 1, wherein the main molecular orientation direction of the inner resin tube is the longitudinal direction.

6. The catheter according to claim 1, wherein in said second region, the longitudinal component of the molecular orientation of said outer resin tube is greater than the longitudinal component of the molecular orientation of said inner resin tube.

7. A catheter as described in claim 1, wherein an opening is provided in the peripheral wall of the outer resin tube, connecting the outside of the outer resin tube with the inner cavity of the inner resin tube, and the opening is located proximal to the distal end of the core material.

8. The catheter of claim 1, further comprising a balloon disposed on the distal portion of said outer plastic tube.

9. A catheter as described in claim 8, wherein the shaft has a fluid supply tube that communicates with the inner cavity of the balloon and through which fluid is supplied, the fluid supply tube is disposed within the inner cavity of the outer resin tube and outside the inner resin tube, and the cross-sectional shape of the inner cavity of the fluid supply tube in a cross section perpendicular to the longitudinal direction is elliptical.

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