Electrode Catheter

Abstract

Provided is a catheter in which twisting of a curved shaft at the distal part of the catheter is prevented, decreases in the bending and pushability of the catheter are prevented, and the expected curve shape can be achieved.　A catheter (1) comprises: a shaft (2); at least one wire (30); a coil (60); a leaf spring (40) that has a first connection part (41) of which a proximal end part is fixed to a distal end part of the coil (60); and a cover tube (50). The coil (60) has a fixed part (61) that is fixed to the shaft (2) to the proximal side of the proximal end of the cover tube (50), and in the longitudinal direction, the length of the fixed part (61) from the distal end to the proximal end of the cover tube (50) is at most 20 turns of the coil (60).

Description

[Technical field]

[0001] The present invention relates to a catheter having a bendable distal portion. [Background technology]

[0002] Electrode catheters having a plurality of electrodes at their distal portions are used to measure potentials in the heart and to perform pacing. Some of these electrode-equipped catheters have a distal portion that can be bent by operating a handle so that the distal portion of the catheter can be easily positioned at a desired site in the heart. In general, the distal portion of such catheters can be bent by pulling a wire fixed inside the tip of the catheter.

[0003] In order to deliver the distal part of the catheter to the optimal site according to the size and purpose of the heart, it is necessary for the distal part of the catheter to be freely curved in the desired direction by wire manipulation. In addition, to prevent the distal part of the catheter from damaging the lumen wall of the living body or moving in an undesired direction, it is necessary to suppress twisting and bending (kinking) of the distal part of the catheter when it is curved. For this reason, various forms have been proposed for fixing the proximal side of the leaf spring for bending.

[0004] As such a catheter, a catheter has been disclosed in which an operating wire and the distal end of a leaf spring serving as a swivel member are fixed to the distal end of a catheter tube, and the proximal end of the swivel member is connected to a tube disposed within the lumen of the catheter tube.

[0005] In the catheters disclosed in Patent Documents 1 and 2, the operation wire is disposed in a tube for the operation wire, the leaf spring is disposed in a catheter tube, and the proximal end is fixed to a coil tube. In Patent Document 2, the tube for the operation wire is fixed to the surface of the leaf spring or the like via an adhesive layer. In the catheter disclosed in Patent Document 3, the leaf spring is fixed to the coil tube via a coil stopper. In the catheter disclosed in Patent Document 4, the operation wire and the leaf spring are disposed in a distal tube, and the proximal end of the leaf spring is fixed to the proximal tube. Furthermore, a protective tube is disposed outside the proximal tube. It is disclosed that the proximal end of the distal tube is located distal to the distal end of the protective tube. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-61350 A [Patent Document 2] JP 2012-200445 A [Patent Document 3] JP 2014-64614 A [Patent Document 4] International Publication No. 2019 / 156059 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in a conventional catheter, when a coil is provided to be connected to the proximal end of the leaf spring, the coil is compressed by the pulling of the wire, and the coil is deformed so as to expand in the radial direction, causing the connection part between the coil and the leaf spring to rotate, which may cause the bending axis of the leaf spring to twist. To prevent this, the connection part can be fixed to the catheter tube, but when fixed, the part becomes hard, and a rigidity step occurs in which the hardness changes suddenly. For this reason, there is a risk that the catheter may break when it is bent, causing kinking, or that the pushability may decrease, causing the force of the wire operation to be difficult to transmit to the tip of the wire. In addition, if a conductor is arranged in the fixing part, the conductor may also be fixed, and when the catheter is bent, the conductor may be taut and adversely affect the curved shape.

[0008] The present invention has been made in consideration of the above circumstances, and its object is to provide a catheter that can achieve the desired curved shape while preventing twisting of the curved axis at the distal part of the catheter, while preventing bending of the catheter and a decrease in pushability. [Means for solving the problem]

[0009] The catheter that has been able to solve the above problem includes a shaft having a distal end and a proximal end and having a longitudinally extending lumen; one or more wires having a distal end and a proximal end, the distal end of which is fixed to the distal end of the shaft at a second connection part and the proximal end of which extends to the proximal end of the shaft; a coil having a distal end and a proximal end and having a longitudinally extending lumen in the shaft lumen, the wire being disposed in the lumen; a leaf spring having a distal end and a proximal end and extending longitudinally in the shaft lumen, the proximal end of the leaf spring being fixed to the distal end of the coil at a first connection part and the distal end of the leaf spring being fixed to the shaft at a first connection part. the coil has a first connection part and a second connection part fixed to the distal end of the shaft; and a cover tube having a distal end and a proximal end and having an inner cavity extending longitudinally in the inner cavity of the shaft, in which a distal portion of a coil including a first connection part, a wire and a leaf spring are disposed, the proximal end of the cover tube being disposed distal to the proximal end of the coil, the coil having a fixing part fixed to the shaft proximal to the proximal end of the cover tube, and the length from the distal end of the fixing part to the proximal end of the cover tube in the longitudinal direction is equal to or less than 20 turns of the coil.

[0010] A portion of the lumen of the cover tube preferably abuts the outside of the coil.

[0011] In the longitudinal direction of the shaft, the length from the distal end of the fixed portion to the distal end of the coil is preferably ⅓ or more of the length of the leaf spring.

[0012] In the longitudinal direction of the shaft, the length from the distal end of the fixed portion to the distal end of the coil is preferably equal to or less than twice the length of the leaf spring.

[0013] The cover tube is preferably not fixed to the shaft.

[0014] The longitudinal length of the cover tube is preferably greater than the longitudinal length of the leaf spring.

[0015] It is preferable that the cover tube extends to the second connection portion, and the cover tube covers the wire and the leaf spring so that the leaf spring and the wire are not exposed in the shaft cavity. Effect of the Invention

[0016] According to the present invention, it is possible to prevent bending and a decrease in pushability while preventing twisting of the bending axis of a catheter having a bendable distal portion, thereby providing a catheter that can achieve a desired curved shape of the catheter distal portion by wire manipulation and can easily deliver the catheter distal portion to a desired position. [Brief description of the drawings]

[0017] [Figure 1] 1 illustrates a plan view of a catheter according to an embodiment of the present invention. [Diagram 2] 2 shows a longitudinal cross-sectional view (partial plan view) of the distal portion of the catheter shown in FIG. 1. [Diagram 3] 3 shows a cross-sectional view of the distal portion of the catheter shown in FIG. 2 taken along line III-III. [Figure 4] 3 shows another example of a cross-sectional view of the distal portion of the catheter shown in FIG. 2 taken along line III-III. [Diagram 5] 3 shows a VV cross-sectional view of the distal portion of the catheter shown in FIG. 2. [Figure 6] 6 shows a cross-sectional view of the distal portion of the catheter shown in FIG. 2 taken along the line VI-VI. [Figure 7] 7 shows a cross-sectional view of the distal portion of the catheter shown in FIG. 2 taken along line VII-VII. [Figure 8] 2 illustrates a plan view of a coil according to an embodiment of the present invention; [Figure 9] 13 is a longitudinal cross-sectional view (partial plan view) of a distal portion of a catheter according to another embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 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 modified as appropriate within the scope of the above and below, and all of these are included in the technical scope of the present invention. In addition, hatching and component symbols may be omitted in each drawing for convenience, but in such cases, the specification and other drawings should be referred to. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, since priority is given to helping understand the features of the present invention.

[0019] The catheter of the present invention includes a shaft having a distal end and a proximal end and having a longitudinally extending lumen; one or more wires having a distal end and a proximal end, the distal end of which is secured to the distal end of the shaft and the proximal end of which extends to the proximal end of the shaft; a coil having a distal end and a proximal end and having a longitudinally extending lumen in the shaft lumen, the wire being disposed in the lumen; a leaf spring having a distal end and a proximal end and extending longitudinally in the shaft lumen, the first connector having a proximal end of the leaf spring secured to the distal end of the coil, and a distal end of the leaf spring secured to the distal end of the shaft. a leaf spring having a second connection portion attached to the shaft; and a cover tube having a distal end and a proximal end and having an inner cavity extending longitudinally in the inner cavity of the shaft, in which a distal portion of a coil including a first connection portion, a wire and a leaf spring are disposed, the proximal end of the cover tube being disposed distal to the proximal end of the coil, the coil having a fixing portion fixed to the shaft proximal to the proximal end of the cover tube, and the length from the distal end of the fixing portion to the proximal end of the cover tube in the longitudinal direction of the shaft is equal to or less than 20 turns of the coil.

[0020] With the above configuration, the catheter of the present invention can bend the distal catheter section from the distal end of the coil by bending the leaf spring connected to the distal end of the shaft by pulling the wire while ensuring the rigidity of the base end side of the distal end of the shaft by the coil. The catheter of the present invention having the above configuration can prevent the twisting of the bending axis of the catheter distal section because the coil in which the wire is arranged in the lumen is not easily deformed, such as by expanding the outer diameter, even if it is compressed by pulling the wire. In addition, since the distal end of the coil and the fixing section are not close to each other, the rigidity step in which the rigidity changes suddenly at the distal end of the coil can be mitigated, and bending of the catheter and a decrease in pushability can be prevented. Furthermore, since the length from the distal end of the fixing section to the proximal end of the cover tube is equal to or less than a predetermined value with respect to the coil, the coil is not easily deformed, such as by twisting, between the distal end of the fixing section and the proximal end of the cover tube. As a result, the catheter of the present invention makes it possible to easily deliver the distal portion of the catheter to the intended location in a blood vessel or the heart, and also prevents the distal portion of the catheter from damaging the inner lumen wall of the body or advancing in an undesired direction.

[0021] Here, in the present invention, the fixing of the coil, the cover tube, and the shaft refers to being fixed by some fixing means such as adhesion with an adhesive or the like, brazing with solder or the like, welding, etc., and does not mean that they are simply in contact or in close contact. For example, the cover tube may be provided on the outside of the coil by thermally shrinking a resin, and in that case, the cover tube may be in close contact with the outside of the coil, but this state is not said to mean that the cover tube and the coil are fixed. Furthermore, if a shaft is provided on the outside by thermal shrinkage or the like, the coil, the cover tube, and the shaft may be in close contact with each other, and the coil and the shaft may be indirectly in close contact with each other, but this state is not said to mean that the coil and the shaft are fixed. Furthermore, even in a portion where the cover tube is not provided in the longitudinal direction and the shaft is provided in close contact with the outside of the coil, this state is not said to mean that the coil and the shaft are fixed.

[0022] A catheter according to an embodiment of the present invention will be described below with reference to Figs. 1 to 9. Fig. 1 shows a plan view of a catheter according to an embodiment of the present invention, and the dotted line shows the state when the distal part of the catheter is curved toward one side of a leaf spring in the radial direction of the shaft. Fig. 2 shows a longitudinal cross-sectional view of the distal part when the catheter shown in Fig. 1 is not curved. In Fig. 2, the coil is shown in plan view. Fig. 3 shows a III-III cross-sectional view of the distal part of the catheter shown in Fig. 2, and Fig. 4 shows another example of the III-III cross-sectional view of the distal part of the catheter shown in Fig. 2. Figs. 5 to 7 show VV cross-sectional views, VI-VI cross-sectional views, and VII-VII cross-sectional views of the distal part of the catheter shown in Fig. 2, respectively. Fig. 8 shows a plan view of a coil according to an embodiment of the present invention in a natural state. Fig. 9 shows a longitudinal cross-sectional view of the distal part when the catheter according to another embodiment of the present invention is not curved. In Fig. 9, the coil is shown in plan view.

[0023] In the present invention, the proximal side refers to the side of the user's hand with respect to the extending direction of the shaft, and the distal side refers to the opposite side of the proximal side, i.e., the side of the subject of treatment. The extending direction of the shaft is also referred to as the longitudinal direction d. L The radial direction d R The radial direction is perpendicular to the extension direction of the shaft. In Figures 1, 2 and 9, the lower side of the figure is the proximal side, and the upper side of the figure is the distal side.

[0024] As shown in FIG. 1, the catheter 1 has a distal end and a proximal end, and extends in a longitudinal direction d. L The catheter has a shaft 2 having a lumen extending therethrough. A tip 20 is preferably disposed at the distal end of the shaft 2, and a handle 7 is preferably disposed at the proximal end of the shaft 2.

[0025] The shaft 2 is inserted into the body from the distal end and delivered to the treatment site. For this reason, it is preferable that the shaft is flexible, and metal or resin can be used as the material. Since it is inserted into the body, it is preferable to use a biocompatible material. Treatment devices such as electrodes and sensors can be placed on the surface of the shaft 2. By providing electrodes on the surface of the shaft 2, it can be used as an electrode catheter that measures cardiac potentials or an ablation catheter that cauterizes tissue.

[0026] In the inner cavity of the shaft 2, an internal structure for bending the catheter 1, and a device for treatment and its internal structure, such as a sensor or a lead wire, can be placed. The distal side of the lead wire is connected to an electrode provided on the surface of the shaft 2, and the proximal side of the lead wire passes through the proximal side of the catheter 1 and is connected to a detector or a power source, so that an electrical signal from the electrode can be received and electricity can be applied to the electrode. L The length, outer diameter, thickness, etc. of the catheter can be selected to be an appropriate size for treatment.

[0027] A tip portion 20 is preferably disposed at the distal end of the shaft 2. The tip portion 20 may be a separate member from the shaft 2, or may be the same member as the shaft 2. When the tip portion 20 is a separate member from the shaft 2, the tip portion 20 may include a portion that is inserted into the inner cavity of the shaft 2 or a portion that protrudes distally from the distal end of the shaft. When the tip portion 20 is the same member as the shaft 2, the tip portion 20 may be formed by sealing the opening at the distal end of the shaft 2 by heat fusion or the like of the distal end portion of the shaft 2.

[0028] A handle 7 is preferably disposed on the proximal side of the shaft 2, and the proximal end of the shaft 2 is preferably fixed inside the handle 7. A conducting wire extending from the inner cavity of the shaft 2 and a wire 30 described below are disposed inside the handle 7. The handle 7 may include a wire manipulation unit 70 to facilitate manipulation of the wire 30. By fixing the proximal end of the wire 30 to the wire manipulation unit 70, the wire 30 can be pulled or the like by manipulating the wire manipulation unit 70, thereby bending the catheter distal section 2D of the catheter 1.

[0029] As shown in FIGS. 2 to 7, the catheter 1 has one or more wires 30, the distal end of which is fixed to the distal end of the shaft 2 and the proximal end of which extends to the proximal end of the shaft 2, and the distal end of the wire 30 is fixed to the distal end of the shaft 2 at a second connection portion 42, and extends in the longitudinal direction d in the inner cavity of the shaft 2. L and a leaf spring 40 extending from the shaft 2. By pulling the wire 30, the shaft 2 can be bent. The leaf spring 40 allows the direction of bending to be set.

[0030] The wire 30 is an operating wire for bending the catheter distal portion 2D of the catheter 1. One or more wires 30 are arranged. For example, by arranging two wires 30, the radial direction d of the leaf spring 40 can be bent by operating each wire 30. R Alternatively, the catheter 1 may be bent to both one side and the other side of the shaft 2. The wire 30 is disposed in the lumen of the shaft 2, the distal end of which is fixed to the distal end of the shaft 2, preferably to the tip portion 20, and the proximal end of which extends to the proximal end of the handle 7. The proximal end of the wire 30 is preferably fixed to the handle 7. The wire 30 may be a metal wire such as stainless steel or a wire made of a synthetic resin such as a fluororesin. The wires 30 may each be a single wire or may have a structure made of multiple wires.

[0031] The leaf spring 40 is a member that determines the bending direction of the catheter 1, and has a distal end and a proximal end. L The leaf spring 40 has a plate-like shape extending in the radial direction d. The leaf spring 40 is preferably disposed along the longitudinal axis of the shaft 2. By having the leaf spring 40 in a plate-like shape, the bending direction of the catheter distal portion 2D of the catheter 1 can be fixed, and the catheter distal portion 2D can be moved in the radial direction d. R The leaf spring 40 can be bent to one side and the other side of the distal end of the shaft 2. The distal end of the leaf spring 40 is fixed to the distal end of the shaft 2. When the tip portion 20 is provided at the distal end of the shaft 2, the distal end of the leaf spring 40 is preferably fixed to the tip portion 20. The proximal end of the leaf spring 40 is fixed to the distal end of the coil 60 by a first connection portion 41. In other words, it can be said that the leaf spring 40 has a first connection portion 41 where the proximal end of the leaf spring 40 is fixed to the distal end of the coil 60, and a second connection portion 42 where the distal end of the leaf spring 40 is fixed to the distal end of the shaft 2.

[0032] The leaf spring 40 is a spring using a plate material, and examples of the material constituting the leaf spring 40 include metals such as stainless steel, titanium, carbon steel, nickel-titanium alloy, cobalt-chromium alloy, and tungsten alloy. Alternatively, examples of the material constituting the leaf spring 40 include synthetic resins such as aromatic polyether ketone resin (e.g., PEEK), polycarbonate resin, and fiber-reinforced resin. Alternatively, the leaf spring 40 may be made of synthetic rubbers such as butadiene rubber, isoprene rubber, styrene-butadiene rubber, ethylene-propylene rubber, acrylic rubber, and silicone rubber, or natural rubber. Among these, the material of the leaf spring 40 is preferably stainless steel.

[0033] The distal end of the wire 30 or the distal end of the leaf spring 40 may be fixed to the shaft 2, and the first connection portion 41 to the coil 60 at the proximal end of the leaf spring 40 may be fixed by fixing the vicinity of the end, rather than directly fixing the end. The method for fixing the distal end and proximal end of the wire 30 and the leaf spring 40 is not particularly limited, but may be, for example, soldering, and when the tip portion 20 or the coil 60 is made of metal, it is preferable to fix them by laser welding.

[0034] As shown in Figs. 2 to 7, a cover tube 50 and a coil 60 are arranged in the lumen of the catheter 1 from the distal side. The cover tube 50 is arranged in the longitudinal direction d L The coil 60 has an inner cavity extending in a longitudinal direction d, and the wire 30 and the leaf spring 40 are disposed in the inner cavity. L The proximal end of the leaf spring 40 is fixed to the distal end of the lumen.

[0035] The cover tube 50 has a distal end and a proximal end, and is arranged in the inner cavity of the shaft 2 in the longitudinal direction d. L 2, the wire 30 and the leaf spring 40 are disposed in the lumen of the cover tube 50. On the proximal side of the cover tube 50, the distal portion of the coil 60 is disposed inside the cover tube 50. The distal portion of the coil 60 disposed in the lumen of the cover tube 50 includes the first connection portion 41 of the coil 60 and the leaf spring 40. Since the distal portion of the coil 60 including at least the first connection portion 41 is disposed inside the cover tube 50, when the wire 30 is pulled to bend the catheter distal portion 2D, the distal side of the coil 60 including the first connection portion 41, which is the base end of the bend, is bent in the radial direction d. RThis can prevent deformation such as bulging, and can prevent the first connection portion 41 between the coil 60 and the leaf spring 40 from rotating and twisting the bending axis of the leaf spring 40. As a result, the catheter distal portion 2D can be curved in a certain direction without twisting. The distal end of the cover tube 50 may extend to the distal end of the shaft 2, or there may be a portion at the distal end of the shaft 2 where the wire 30 and the leaf spring 40 are exposed from the cover tube 50. The proximal end of the cover tube 50 is disposed distal to the proximal end of the coil 60. This allows the coil 60 and the shaft 2 to be fixed together.

[0036] The cover tube 50 is preferably flexible like the shaft 2, and may be made of synthetic resin such as aromatic polyether ketone resin (e.g., PEEK), polycarbonate resin, polyamide resin, polyester resin, polyurethane resin, polyolefin resin, vinyl chloride resin, silicone resin, natural rubber, synthetic rubber, etc. It is preferable that the synthetic resin is provided on the outside of the coil 60 by thermal shrinkage.

[0037] The coil 60 has a distal end and a proximal end, and extends in the lumen of the shaft 2 in a longitudinal direction d. L The coil 60 has an inner cavity extending from the leaf spring 40 to the inner cavity of the shaft 2. The coil 60 is disposed on the proximal side of the leaf spring 40 in the inner cavity of the shaft 2, and the proximal end of the leaf spring 40 is fixed to the distal end of the coil 60. The wire 30 is disposed in the inner cavity of the coil 60. The first connection portion 41 between the coil 60 and the leaf spring 40 is sufficient as long as the leaf spring 40 and the coil 60 are fixed to each other, and the proximal end of the leaf spring 40 may be disposed in the inner cavity of the coil 60 or may be located outside the coil 60. Alternatively, the proximal end of the leaf spring 40 may be fixed to the distal end of the coil 60. In the first connection portion 41 of the leaf spring 40, the coil 60 receives the proximal end of the leaf spring 40 in the inner cavity, and it is preferable that a part of the leaf spring 40 is disposed in the inner cavity of the coil 60 and the proximal end of the leaf spring 40 is fixed. This makes it possible to firmly fix the leaf spring 40 to the coil 60.

[0038] By disposing the coil 60, it is possible to ensure the rigidity of the base end side of the curved catheter distal section 2D. From the viewpoint of ensuring the rigidity of the base end side of the curved catheter distal section 2D, it is preferable that the coil 60 is an uncompressed, so-called densely wound coil. If the coil 60 is uncompressed, the catheter distal section 2D can be curved with the distal end of the coil 60 as the base point. Strictly speaking, an uncompressed coil is a coil having a length L that is smaller than the total length L of the coil in its natural state and the total length L of the coil when it is maximally compressed. C Compared to L C / L is 1, but L C When / L is 0.9 or more, or 0.95 or more, the coil is substantially uncompressed and is included in the uncompressed coil. The proximal end of the coil 60 may extend to the proximal end of the shaft 2, or may be disposed midway along the shaft 2. The coil 60 may be switched to a different tube midway along the shaft 2.

[0039] The coil 60 is preferably flexible, and may be made of metal or resin, and may be made of metal wire such as stainless steel or nickel-titanium alloy, or synthetic resin wire such as aromatic polyetherketone resin (e.g., PEEK) or polycarbonate resin. The cross-sectional shape of the coil wire forming the coil 60 may be circular, rectangular, or a combination thereof. In particular, the coil 60 is preferably a coil using stainless steel wire with a circular cross section. The coil wire diameter, coil diameter, and length of the coil 60 may be appropriately selected as necessary. In particular, the coil 60 is preferably a coil in which a metal wire is wound. The diameter of the coil wire forming the coil 60 is preferably 0.1 mm to 0.5 mm. When the coil 60 is made of a coil wire with a rectangular cross section, one side of the rectangle may be 0.05 mm to 1 mm. Since the internal structure of the catheter 1 of the present invention changes at the distal end of the coil 60, it is preferable to select the size, flexibility, and material of the coil 60 so that there is no large change in the hardness of the catheter 1 between the distal and proximal sides of the distal end of the coil 60.

[0040] The coil 60 has a fixing portion 61 that is fixed to the shaft 2 proximal to the proximal end of the cover tube 50. By fixing the coil 60 to the shaft 2, deformation of the coil 60 can be prevented, and twisting of the shaft 2 can be prevented, allowing the catheter distal portion 2D to be curved in a certain direction without twisting. The fixing portion 61 is provided by fixing using some kind of fixing means, such as bonding with an adhesive or brazing with solder or the like.

[0041] As shown in FIG. 2, the longitudinal direction d of the shaft 2 L In the longitudinal direction d of the fixing portion 61, the length d1 from the distal end of the fixing portion 61 to the proximal end of the cover tube 50 is equal to or less than 20 turns of the coil 60 in the natural state of the coil 60. L Although d1 depends on the length of the coil 60 disposed in the inner cavity of the cover tube 50 and the length of the coil 60 disposed in the inner cavity of the cover tube 50, it is preferable that d1 is short. L It is preferable that the lengths are shorter in the order of length d1, length d2, and length d3. This allows the fixing part 61 to be disposed immediately adjacent to the proximal end of the cover tube 50, thereby preventing the coil 60 from being deformed or twisted. In addition, the length d1 of the coil 60 in the longitudinal direction of the coil 60 that is not disposed in the lumen of the cover tube 50 on the distal side of the fixing part 61 is preferably shorter than the length d2. L Since the length of the coil 60 can be shortened, when the wire 30 is pulled or otherwise subjected to a bending operation at a portion distal to the fixing portion 61 and proximal to the proximal end of the cover tube 50, problems such as twisting of the coil 60 can be prevented, and the catheter distal portion 2D can be curved in a fixed direction. Furthermore, since the fixing portion 61 is provided proximal to the proximal end of the cover tube 50, the fixing portion 61 does not overlap with the distal end of the coil 60 or the first connection portion 41 that fixes the coil 60 and the leaf spring 40, and a rigidity step in which the rigidity of the shaft 2 changes suddenly is unlikely to occur, and therefore bending and a decrease in pushability can be prevented when the catheter distal portion 2D is curved.

[0042] As shown in FIGS. 2 to 4, the fixing portion 61 is provided between the outer periphery of the coil 60 and the inner periphery of the shaft 2, and is aligned in the longitudinal direction d of the coil 60 and the shaft 2. L The length of the fixing portion 61 is 360°. The fixing portion 61 may be provided on the entire circumference of 360° between the outer circumference of the coil 60 and the inner circumference of the shaft 2 as shown in FIG. 3, or may be provided on a part of the circumference as shown in FIG. 4. When the fixing portion 61 is provided on a part of the circumference of 360° as shown in FIG. 4, the total angle of the fixing portion 61 on the circumference is preferably 60° or more, more preferably 90° or more. If the total angle of the fixing portion 61 on the circumference is the above or more, the fixing strength can be ensured. In addition, the total angle of the fixing portion 61 on the circumference may be 240° or less, or may be 180° or less. If the total angle of the fixing portion 61 on the circumference is the above or less, when the catheter 1 has a conductor connected to an electrode or the like arranged at the distal end of the catheter distal portion 2D, a passage for inserting the conductor can be ensured in the space formed between the outer circumference of the coil 60 and the inner circumference of the shaft 2. In such a configuration, since the lead wire is not fixed, it is possible to prevent the lead wire from being pulled when the catheter distal portion 2D is bent, and it is possible to perform the bending operation smoothly.

[0043] The longitudinal direction d of the fixing portion 61 L The length of the fixing portion 61 in the longitudinal direction d is not particularly limited, but is preferably 50 turns or less of the coil 60, more preferably 30 turns or less, and even more preferably 10 turns or less. L If the length of the fixing portion 61 is long, the rigidity of the shaft 2 at the portion where the fixing portion 61 is provided will be high, and there is a risk of problems such as bending or reduced pushability due to the difference in rigidity. LIf the length of the fixing part 61 is equal to or less than the above, it is possible to make it difficult for a rigidity difference in the shaft 2 to occur due to the fixing part 61, and therefore it is possible to bend the catheter distal section 2D without problems such as bending or reduced pushability. Furthermore, if the catheter 1 has a conductor connected to an electrode or the like disposed at the distal end of the catheter distal section 2D, the conductor is disposed inside the shaft 2 and outside the coil 60. Therefore, even if the fixing part 61 is provided around the entire outer periphery of the coil 60, the longitudinal direction d of the fixing part 61 is not large. L Since the length is short, the fixing of the conductor wire can be minimized, and the conductor wire can be prevented from being pulled, allowing the bending operation to be performed smoothly.

[0044] Here, one turn of the coil 60 refers to the axial length of one turn of the coil wire forming the coil 60 in its natural state, as shown in Fig. 8. When the coil 60 is an uncompressed coil, the total length L of the coil in its natural state and the total length L of the coil when it is maximally compressed are C Compared to L C When / L is 1, one turn of the coil 60 coincides with the wire diameter of the coil wire forming the coil 60. One turn of the coil 60 can be measured as one turn S shown in Fig. 8. Therefore, 20 turns of the coil 60 is 20 times the length of one turn S.

[0045] The catheter distal section 2D of the catheter 1 can be curved in a section from where the leaf spring 40 is exposed from the distal end of the coil 60 to where the leaf spring 40 is fixed to the distal end of the shaft 2, for example, to the tip section 20. Therefore, the length of the curved section of the catheter 1 can be appropriately set depending on the length of the leaf spring 40 and the positions of the tip section 20 and the first connection section 41.

[0046] It is preferable that a part of the lumen of the cover tube 50 abuts against the outside of the coil 60. The cover tube 50 may be provided on the outside of the coil 60 by heat shrinkage or the like, so that it is in close contact with the outside of the coil 60. By the cover tube 50 abutting against the outside of the coil 60, it is possible to prevent the coil 60 from being deformed when the wire 30 is operated. The cover tube 50 does not need to abut against the outside of the coil 60 in the entire part containing the coil 60, and for example, a part from the distal end of the coil 60 to a slightly proximal side, for example, a part of the coil 60 of about three turns or less, may not abut against the cover tube 50. In this way, even if there is a part of the cover tube 50 that does not abut against the outside of the coil 60, the cover tube 50 abuts against the coil 60 in most of the part containing the coil 60, so that deformation of the coil 60 can be prevented.

[0047] Longitudinal direction of shaft 2 d L In the catheter distal portion 2D, the length d2 from the distal end of the fixed portion 61 to the distal end of the coil 60 is preferably 1 / 3 or more of the length of the leaf spring 40. L In the portion where the coil 60 is present, the stiffness is high due to the stiffness of the coil 60 itself, and the stiffness is low in the portion where the coil 60 is not present. In addition, since the first connection portion 41 to which the leaf spring 40 is fixed to the distal end of the coil 60 is also a portion that increases the stiffness, a certain degree of stiffness change is unavoidable at the distal end of the coil 60. On the other hand, the stiffness is also high at the fixing portion 61, so that the fixing portion 61 also causes a stiffness step. However, if the catheter 1 is configured so that the length from the distal end of the fixing portion 61 to the distal end of the coil 60 is equal to or greater than the above-mentioned predetermined value with respect to the length of the leaf spring 40, which is a bending member, the stiffness change at the distal end of the coil 60 and the stiffness change due to the fixing portion 61 do not overlap, so that the stiffness change can be dispersed, and as a result, a sudden stiffness step in the shaft 2 can be prevented, and bending and a decrease in pushability can be made less likely to occur when the catheter distal portion 2D is bent. LIn the embodiment, the length d2 from the distal end of the fixed portion 61 to the distal end of the coil 60 may be ½ or more, or ¾ or more, of the length of the leaf spring 40.

[0048] Longitudinal direction of shaft 2 d L In the above, it is preferable that the length d2 from the distal end of the fixing part 61 to the distal end of the coil 60 is equal to or less than twice the length of the leaf spring 40. If the length d2 from the distal end of the fixing part 61 to the distal end of the coil 60 exceeds the above-mentioned predetermined value, when the entire shaft 2 is twisted, the leaf spring 40 and the coil 60 may become twisted due to friction with the inner layer of the shaft 2, and the coil 60 may be fixed to the shaft 2 in this state. In that case, even if the shaft 2 is returned to an untwisted state, the leaf spring 40 may remain twisted, and the catheter distal part 2D may not be bent in a certain direction but may be bent in a spiral shape, making it impossible to deliver the catheter distal part 2D to the intended position. As described above, if the length d2 from the distal end of the fixing portion 61 to the distal end of the coil 60 is equal to or less than twice the length of the leaf spring 40, which is the bending member, the coil 60 can be fixed to the shaft 2 in a state where the leaf spring 40 and the coil 60 are not twisted, and the catheter distal portion 2D can be curved in a certain direction without twisting. L The length d2 from the distal end of the fixed portion 61 to the distal end of the coil 60 is more preferably 1.5 times or less the length of the leaf spring 40, and further preferably 1 time or less.

[0049] It is preferable that the cover tube 50 is not fixed to the shaft 2. Since the cover tube 50, in which the distal portion of the coil 60 including the first connection portion 41 between the leaf spring 40 and the coil 60 is disposed in the lumen, is not fixed to the shaft 2, the change in rigidity of the distal end portion of the coil 60 and the change in rigidity due to the fixing of the cover tube 50 to the shaft 2 do not overlap, and a sudden change in rigidity is unlikely to occur, so that a rigidity step in the catheter distal portion 2D can be prevented, and bending and a decrease in pushability are unlikely to occur.

[0050] Longitudinal direction d of cover tube 50 LThe length of the leaf spring 40 in the longitudinal direction d L It is preferable that the length of the cover tube 50 is longer than the length of the longitudinal direction d. L The length of the leaf spring 40 in the longitudinal direction d L Since the length of the cover tube 50 is longer than the length of the coil 60, the cover tube 50 can accommodate the distal side of the coil 60 including the first connection portion 41 in the lumen while being extended in the longitudinal direction d. L In this case, the leaf spring 40 and the wire 30 distal to the first connection portion 41 can be housed in the inner cavity, which makes it possible to prevent deformation of the coil 60 and to protect the leaf spring 40 and the wire 30.

[0051] As shown in FIG. 9, the cover tube 50 extends to the second connection portion 42 where the distal end of the leaf spring 40 is fixed to the shaft 2, and it is preferable that the cover tube 50 covers the wire 30 and the leaf spring 40 so that the leaf spring 40 and the wire 30 are not exposed in the lumen of the shaft 2. The cover tube 50 covers the entire length of the wire 30 and the leaf spring 40, so that the leaf spring 40 and the wire 30, which repeat bending motions by bending operations, can be sufficiently protected in the bendable catheter distal portion 2D. In addition, when the catheter 1 has a conductor connected to an electrode or the like disposed at the distal end of the catheter distal portion 2D, the conductor is disposed inside the shaft 2 and outside the cover tube 50, but since the leaf spring 40 and the wire 30 are disposed in the lumen of the cover tube 50, the leaf spring 40 and the wire 30 are disposed outside the cover tube 50 and are not exposed in the lumen of the shaft 2, so that the leaf spring 40 and the wire 30 can be prevented from interfering with the conductor. The cover tube 50 extending to the second connection portion 42 includes the cover tube 50 extending to the proximal end of the second connection portion 42 and the cover tube 50 extending to near the proximal end of the second connection portion 42.

[0052] This application claims the benefit of priority based on Japanese Patent Application No. 2020-117631, filed on July 8, 2020. The entire contents of the specification of Japanese Patent Application No. 2020-117631, filed on July 8, 2020, are incorporated by reference into this application. [Explanation of symbols]

[0053] 1: Catheter 2: Shaft 2D: Distal part of the catheter 7: Handle 20:Tip 30: Wire 40: Leaf spring 41: First connection part 42: Second connection part 50: Cover tube 60: Coil 61: Coil and shaft fixing part 70: Wire operation unit d1: Length from the distal end of the fixing part to the proximal end of the cover tube d2: Length from the distal end of the fixation part to the distal end of the coil d L : Longitudinal direction d R :radial direction S: 1 turn of coil

Claims

1. a shaft having a distal end and a proximal end and having a longitudinally extending lumen; one or more wires having a distal end and a proximal end, the distal end being secured to the distal end of the shaft and the proximal end extending to the proximal end of the shaft; a coil having a distal end and a proximal end, the coil having a lumen extending in the longitudinal direction within the shaft lumen, the wire being disposed within the lumen; a leaf spring having a distal end and a proximal end and extending in the longitudinal direction within the lumen of the shaft, the leaf spring having a first connection portion where the proximal end of the leaf spring is fixed to the distal end of the coil and a second connection portion where the distal end of the leaf spring is fixed to the distal end of the shaft; a cover tube having a distal end and a proximal end, the cover tube having an inner cavity extending in the longitudinal direction in an inner cavity of the shaft, the distal portion of the coil including the first connection portion, the wire, and the leaf spring being disposed within the inner cavity, the proximal end of the cover tube being disposed distally of the proximal end of the coil; An electrode disposed on a surface of the shaft; a conductor connected to the electrode and disposed inside the shaft and outside the coil; the coil has a fixing portion fixed to the shaft proximal to the proximal end of the cover tube, the distal end of the fixing portion and the proximal end of the cover tube are spaced apart in the longitudinal direction, and the length from the distal end of the fixing portion to the proximal end of the cover tube is 20 turns of the coil or less; An electrode catheter, wherein the conductor is fixed to the fixed portion.

2. 2. The electrode catheter of claim 1, wherein a portion of the lumen of the cover tube abuts an outside of the coil.

3. 3. The electrode catheter according to claim 1, wherein the length from the distal end of the fixed portion to the distal end of the coil in the longitudinal direction is equal to or greater than 1 / 3 of the length of the leaf spring.

4. 4. The electrode catheter according to claim 1, wherein the length from the distal end of the fixed portion to the distal end of the coil in the longitudinal direction is equal to or less than twice the length of the leaf spring.

5. The electrode catheter according to any one of claims 1 to 4, wherein the cover tube is not fixed to the shaft.

6. 6. The electrode catheter according to claim 1, wherein the length of the cover tube in the longitudinal direction is longer than the length of the leaf spring in the longitudinal direction.

7. The electrode catheter according to any one of claims 1 to 6, wherein the cover tube extends to the second connection portion, and the cover tube covers the wire and the leaf spring, so that the leaf spring and the wire are not exposed in the shaft lumen.

8. 8. The electrode catheter according to claim 1, wherein, in the longitudinal direction, the length of the portion where the coil is disposed in the inner cavity of the cover tube decreases in the following order: the length of the fixing portion, and the length from the distal end of the fixing portion to the proximal end of the cover tube.

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