catheter

Abstract

To provide a catheter capable of changing its slidability according to a load imposed on an external surface.SOLUTION: A catheter 1 includes a long-sized tube body 2 having a tip part and a base end part. The tube body 2 includes a coating part 40 formed of a low friction material on an external surface. The coating part 40 includes a first surface 41 and a second surface 42 disposed on mutually opposite sides in a circumferential direction of the tube body 2. The rate of change in the friction coefficient of the first surface 41 to a change in the load imposed on the first surface 41 is greater than the rate of change in the friction coefficient of the second surface 42 to a change in the load imposed on the second surface 42.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a catheter used within a lumen such as a blood vessel.

Background Art

[0002] As a method for treating lesions such as stenosis and occlusion occurring in blood vessels, there is endovascular treatment in which treatment is performed from within the blood vessel using a device inserted percutaneously into the blood vessel. In endovascular treatment, a catheter is used to reach a diagnostic contrast agent or a guide wire to the lesion site.

[0003] In order for the catheter to reach a target position such as a lesion through a thin and complexly curved blood vessel, the frictional resistance on the outer surface of the catheter needs to be low. For this reason, it is generally performed to coat at least a part of the outer surface of the catheter with a lubricating layer having a low frictional resistance. In addition, it is also known to provide an uneven structure on the lubricating layer (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A catheter with a low frictional resistance on the outer surface due to the lubricating layer is likely to slide against the blood vessel wall. For this reason, at a branch portion of the blood vessel, a catheter whose tip portion faces the branch direction may receive a force in a direction different from the branch direction, and the tip portion may slide off the blood vessel wall and enter a blood vessel in an unintended direction.

[0006] While a catheter can prevent slippage and dislodgement at vascular bifurcations by increasing the frictional resistance of its outer surface, this reduces its sliding ability in narrowed areas of the vessel. Therefore, a catheter is desired that is less likely to slip against the vessel wall at vascular bifurcations where the outer surface is not subjected to load, and more likely to slip against the vessel wall at narrowed areas where the outer surface is subjected to load.

[0007] The present invention was made to solve the above-mentioned problems, and aims to provide a catheter that can change its sliding properties in response to the load applied to its outer surface. [Means for solving the problem]

[0008] (1) A catheter that achieves the above objective is a catheter comprising a long tubular body having a tip and a proximal end, wherein the tubular body has a covering portion formed of a low-friction material on its outer surface, and the covering portion has a first surface and a second surface arranged on opposite sides in the circumferential direction of the tubular body, wherein the rate of change of the coefficient of friction of the first surface in response to a change in load applied to the first surface is greater than the rate of change of the coefficient of friction of the second surface in response to a change in load applied to the second surface. [Effects of the Invention]

[0009] As described above, the catheter has different rates of change in the coefficient of friction with respect to changes in the load applied to its outer surface between the first and second surfaces. Therefore, by changing the surface that comes into contact with the blood vessel wall according to the conditions inside the blood vessel into which it is inserted, it is possible to achieve both bifurcation selectivity and passage through stenosis.

[0010] (2) In the catheter described in (1) above, the first surface may have a periodic uneven surface, and the second surface may be a smooth surface. This allows the first surface to have a high rate of change in the coefficient of friction in response to changes in the load applied to its outer surface due to its uneven surface.

[0011] (3) In the catheter described in (1) or (2) above, the uneven shape of the first surface may have a height difference of 5 μm to 30 μm when swollen, and the spacing in the longitudinal direction of the tube may be in the range of 3 mm to 50 mm. This allows the catheter to set the coefficient of friction of the first surface within an appropriate range.

[0012] (4) In any one of the catheters described in (1) to (3) above, the first surface and the second surface may be formed at least at the tip of the tube. This allows the catheter to have high selectivity for bifurcation by bringing the surface with the higher coefficient of friction at the tip of the tube into contact with the blood vessel wall at the bifurcation of the blood vessel.

[0013] (5) In any one of the catheters described in (1) to (4) above, the coefficient of friction of the first surface when unloaded may be greater than the coefficient of friction of the second surface when unloaded. This allows the catheter to have a high coefficient of friction of the first surface when unloaded. As a result, the catheter can have high selectivity for bifurcation by bringing the first surface into contact with the blood vessel wall at the bifurcation of a blood vessel.

[0014] (6) In any one of the catheters described in (1) to (4) above, the coefficient of friction of the first surface when unloaded may be smaller than the coefficient of friction of the second surface when unloaded. This allows the catheter to have an even lower coefficient of friction on the first surface when a load is applied than on the second surface. As a result, the catheter can pass through narrowed blood vessels more easily.

[0015] (7) In any one of the catheters described in (1) to (6) above, the covering portion may be made of a hydrophilic polymer that becomes gel-like when swollen. This allows the catheter to take on a predetermined shape when inserted into a blood vessel and swell, enabling it to perform the functions of the first and second surfaces. [Brief explanation of the drawing]

[0016] [Figure 1]It is a plan view showing a catheter according to an embodiment. [Figure 2] It is a cross-sectional view showing an enlarged part of the tube body of the catheter. [Figure 3] It is a cross-sectional view taken along line A-A in FIG. 2. [Figure 4] It is a plan view showing a state where the sliding surface of the catheter according to the embodiment is in contact with the blood vessel wall. [Figure 5] It is a plan view showing a state where the resistance surface of the catheter according to the embodiment is in contact with the blood vessel wall.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the dimensions in the drawings may be exaggerated for convenience of explanation and may be different from the actual dimensions. In the present specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted. In the present specification, the side of the catheter inserted into the blood vessel is referred to as the "tip side", and the side for operation is referred to as the "base end side".

[0018] In the description of the present specification, the direction in which the catheter extends in the natural state (a straight state without applying an external force) is defined as the "longitudinal direction". The rotational direction with respect to the longitudinal direction of the catheter as the reference axis is defined as the "circumferential direction". Also, in the catheter, the side inserted into the blood vessel is the tip side, and the end side opposite to the tip side is the base end side. Further, a portion including a certain range in the longitudinal direction from the tip (the foremost end) is defined as the "tip portion", and a portion including a certain range in the longitudinal direction from the base end (the most proximal end) is defined as the "base end portion".

[0019] In the present specification, "X~Y" indicating a range includes X and Y and means "X or more and Y or less".

[0020] The catheter 1 according to this embodiment is a device that is percutaneously inserted into a blood vessel and used for performing treatment or diagnosis within the blood vessel. As shown in FIG. 1, the catheter 1 has a long tubular body 2 having a distal end portion and a proximal end portion, a hub 3 connected to the proximal end of the tubular body 2, and a kink-resistant protector 4 surrounding the connection site between the tubular body 2 and the hub 3.

[0021] The tubular body 2 is a flexible tubular member, and a lumen 5 is formed inside from the proximal end to the distal end. The guide wire is inserted through the lumen 5 when the catheter 1 is inserted into the blood vessel. Further, the lumen 5 can be used as a passage for a contrast agent, a therapeutic agent, an embolization substance, and a medical device.

[0022] The effective length of the tubular body 2 is not particularly limited, but is, for example, 1300 mm to 1500 mm. The effective length of the tubular body 2 is the length of the portion that can be inserted into a blood vessel or a sheath. In this embodiment, the effective length is the length from the foremost end of the kink-resistant protector 4 to the foremost end of the tubular body 2.

[0023] The hub 3 is liquid-tightly fixed to the proximal end portion of the tubular body 2 by an adhesive, heat fusion, a stopper (not shown), or the like. The hub 3 functions as an insertion port for a guide wire or a medical device into the lumen 5, an injection port for a contrast agent, a therapeutic agent, or an embolization substance into the lumen 5, and the like. Further, the hub 3 also functions as a gripping portion when operating the catheter 1. The hub 3 has a mark portion 6 on the side of the first surface 41 of the tubular body 2 and on the side that is in the same direction in the circumferential direction. Note that the mark portion 6 may be disposed on the side of the second surface 42 of the tubular body 2 and on the side that is in the same direction in the circumferential direction.

[0024] The hub 3 is not particularly limited, but is formed of a resin such as polycarbonate, polyamide, polysulfone, polyarylate, or a methacrylate-butylene-styrene copolymer.

[0025] The kink protector 4 is provided to surround the connection point between the pipe body 2 and the hub 3, and suppresses kinking of the pipe body 2 at the connection point between the pipe body 2 and the hub 3. The kink protector 4 is made of an elastic material such as natural rubber or silicone resin.

[0026] As shown in Figures 2 and 3, the pipe body 2 comprises an inner layer 10, a reinforcing body 20 positioned outside the inner layer 10, an outer layer 30 positioned outside the inner layer 10 and the reinforcing body 20, and a covering portion 40 that covers a part of the outer surface of the outer layer 30.

[0027] The inner layer 10 has a lumen 5 formed inside. The inner layer 10 is made of a fluororesin such as polytetrafluoroethylene (PTFE) or a low-friction material such as high-density polyethylene (HDPE).

[0028] The reinforcing body 20 is formed by braiding multiple wires 21 in a tubular shape with gaps between them around the outer circumference of the inner layer 10. The wires 21 used in the reinforcing body 20 are made of metal wires such as stainless steel, platinum (Pt) or tungsten (W), resin fibers, carbon fibers, glass fibers, etc.

[0029] The outer layer 30 is a tubular member that covers the outer circumference of the inner layer 10 and the reinforcing body 20. The hardness of the outer layer 30 increases stepwise or gradually from the tip to the base. For example, the hardness of the material forming the area of ​​the outer layer 30 that extends more than 500 mm from the tip to the base is about four times that of the material forming the area of ​​the outer layer 30 that extends 100 mm or less from the tip to the base. As a result, the bending rigidity of the tube 2 is low at the tip and high at the base.

[0030] The outer layer 30 is formed from thermoplastic resins such as polyolefins (polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or mixtures of two or more thereof), polyvinyl chloride, polyamide, polyester elastomer, polyamide elastomer, polyurethane, polyurethane elastomer, polyimide, fluororesin, or mixtures thereof, or thermosetting resins such as epoxy resins.

[0031] The covering portion 40 is formed on the outer surface of the outer layer 30 over a predetermined length, extending from the tip to the proximal end. The covering portion 40 is expected to protrude from the tip opening of a guiding catheter (not shown) toward the tip and be positioned within a blood vessel.

[0032] The coating portion 40 is formed from a low-friction material that reduces friction. The low-friction material forming the coating portion 40 is preferably a hydrophilic polymer that becomes gel-like when swollen. The hydrophilic polymer can be a cellulose polymer, a polyethylene oxide polymer, a maleic anhydride polymer (e.g., a maleic anhydride copolymer such as a methyl vinyl ether-maleic anhydride copolymer), an acrylamide polymer (e.g., a block copolymer of polyacrylamide, glycidyl methacrylate-dimethylacrylamide), a water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidone, or derivatives thereof. The coating portion 40 is formed in layers on the outer surface of the outer layer 30 by dip coating the catheter 1 with the low-friction material.

[0033] The covering portion 40 has a first surface 41 and a second surface 42 that are arranged on opposite sides of the circumferential direction of the pipe body 2. The first surface 41 has a periodic uneven shape along the long axis of the pipe body 2. The second surface 42 is a smooth surface.

[0034] The uneven surface of the first surface 41 has a height difference of 5 μm to 30 μm when swollen, and the spacing in the long axis direction of the tube body 2 is in the range of 3 mm to 50 mm.

[0035] The uneven shape of the first surface 41 is not limited to a shape in which the unevenness repeats along the long axis of the tube 2, but may also be other shapes such as ring-shaped, spiral-shaped, or moth-eye structures that appear periodically along the long axis of the tube 2.

[0036] The coating portion 40, formed from a hydrophilic polymer, experiences a reduction in its coefficient of friction when a load is applied to its surface and it is pressed. The rate of change P1 of the coefficient of friction Fr1 of the first surface 41, which has an uneven shape, in response to a change in the load applied to the first surface is greater than the rate of change P2 of the coefficient of friction Fr2 of the second surface 42 in response to a change in the load applied to the second surface 42. Therefore, when a similar load is applied to the surface, the coefficient of friction Fr1 of the first surface 41 decreases significantly more than the coefficient of friction Fr2 of the second surface 42.

[0037] The absolute values ​​of the frictional resistance on the first surface 41 and the second surface 42 can be adjusted by the thickness of the coating layer 40 and the degree of crosslinking of the hydrophilic polymer. Therefore, the friction coefficient Fr1 of the first surface 41 under no load can be made greater than or less than the friction coefficient Fr2 of the second surface 42 under no load. In this example, the friction coefficient Fr1 of the first surface 41 under no load is assumed to be greater than the friction coefficient Fr2 of the second surface 42 under no load.

[0038] Next, the method of using the catheter 1 according to this embodiment will be described.

[0039] In endovascular treatment procedures, the surgeon inserts a guidewire for the guiding catheter into the blood vessel. Next, the surgeon advances the guiding catheter, through which the guidewire has been inserted, along the guidewire. After this, the surgeon removes the guidewire, leaving the guiding catheter near the lesion in the blood vessel. Next, the surgeon inserts catheter 1, through which the guidewire for catheter 1 has been inserted, into the blood vessel via the lumen of the guiding catheter. The surgeon then causes the tubular body 2, covered by the covering portion 40 of catheter 1, to protrude into the blood vessel through the tip opening of the guiding catheter.

[0040] Once the tip of the tube 2 reaches the bifurcation of the blood vessel, the operator can determine the orientation of the first surface 41 and the second surface 42 of the catheter 1 inside the blood vessel by the direction of the mark 6 on the hub 3 which is manipulated by hand, and bring the first surface 41 of the catheter 1 into contact with the blood vessel wall at the bifurcation, as shown in Figure 4(a). At this time, since no load is applied to the surface of the covering 40, the coefficient of friction Fr1 of the first surface 41 is greater than the coefficient of friction Fr2 of the second surface 42. Therefore, the resistance force from the blood vessel wall accompanying the sliding of the tube 2 is increased. This prevents the tip of the catheter 1 from slipping off at the bifurcation and mistakenly entering a blood vessel in the wrong direction. After that, the operator can proceed with the insertion of the catheter 1 as shown in Figure 4(b).

[0041] Once the tip of the tube 2 reaches the narrowed portion of the blood vessel, the operator passes the tip of the tube 2 through the narrowed portion. As shown in Figure 5, the surface of the catheter 1 is pressed against the surrounding blood vessel wall as it passes through the narrowed portion of the blood vessel. As a result, the covering portion 40 is subjected to load on both the first surface 41 and the second surface 42. The first surface 41, which has an uneven shape, has a greater rate of change P1 of the coefficient of friction Fr1 in response to changes in load when a load is applied than the first surface 42, which has a smooth surface, so the coefficient of friction Fr1 decreases significantly. The coefficient of friction Fr2 also decreases on the second surface 42 when a load is applied. As a result, the catheter 1 has good sliding properties in the narrowed portion and its passage through the narrowed portion is improved.

[0042] The coefficient of friction Fr1 of the first surface 41 under no load may be smaller than the coefficient of friction Fr2 of the second surface 42 under no load. In this case, the operator brings the second surface 42, which has a greater coefficient of friction under no load than the first surface 41, into contact with the blood vessel wall at the bifurcation of the blood vessel. Furthermore, when the catheter 1 passes through a stenosis, the coefficient of friction Fr1 of the first surface 41, which has an uneven shape, becomes smaller than that of the second surface 42, which has a smooth surface. As a result, the catheter 1 can achieve better sliding properties in the stenosis.

[0043] As described above, the catheter 1 of embodiment (1) of this embodiment is a catheter 1 comprising a long tube 2 having a tip and a proximal end, wherein the tube 2 has a covering portion 40 formed of a low-friction material on its outer surface, and the covering portion 40 has a first surface 41 and a second surface 42 that are arranged on opposite sides in the circumferential direction of the tube 2, and the rate of change of the friction coefficient of the first surface 41 in response to a change in load applied to the first surface 41 is greater than the rate of change of the friction coefficient of the second surface 42 in response to a change in load applied to the second surface 42. With the catheter 1 configured in this way, since the rate of change of the friction coefficient in response to a change in load applied to the outer surface is different for the first surface 41 and the second surface 42, by changing the surface that comes into contact with the blood vessel wall according to the conditions inside the blood vessel into which it is inserted, both bifurcation selectivity and stenosis passage are possible.

[0044] In the catheter 1 of embodiment (2), the first surface 41 has a periodic uneven surface, and the second surface 42 is a smooth surface. As a result, the first surface 41 can increase the rate of change of the coefficient of friction in response to changes in the load applied to the outer surface due to its uneven surface.

[0045] In the catheter 1 of embodiment (3), the uneven shape of the first surface 41 is such that the height difference when swollen is in the range of 5 μm to 30 μm, and the spacing in the longitudinal direction of the tube 2 is in the range of 3 mm to 50 mm. This allows the catheter 1 to set the coefficient of friction of the first surface 41 to an appropriate range.

[0046] In the catheter 1 of embodiment (4), the first surface 41 and the second surface 42 are formed on at least the tip of the tube 2, in any one of the catheters 1 of embodiments (1) to (3). As a result, the catheter 1 can increase the selectivity for bifurcation by bringing the surface of the tip of the tube 2 with the higher coefficient of friction into contact with the blood vessel wall at the bifurcation of the blood vessel.

[0047] In the catheter 1 of embodiment (5), the coefficient of friction of the first surface 41 under no load is greater than the coefficient of friction of the second surface 42 under no load, in any one of the catheters 1 of embodiments (1) to (4). As a result, the catheter 1 can increase the selectivity of the bifurcation by bringing the first surface 41 into contact with the blood vessel wall at the bifurcation of the blood vessel.

[0048] In the catheter 1 of embodiment (6), the coefficient of friction of the first surface 41 under no load is smaller than the coefficient of friction of the second surface 42 under no load, in any one of the catheters 1 of embodiments (1) to (4). As a result, the coefficient of friction of the first surface 41 when a load is applied to the catheter 1 can be made even lower than that of the second surface 42. Therefore, the catheter 1 can pass through narrowed parts of blood vessels more easily.

[0049] In embodiment (7), the catheter 1 is one of the catheters 1 of embodiments (1) to (6), in which the covering portion 40 is formed of a hydrophilic polymer that becomes gel-like when swollen. As a result, the catheter 1 takes on a predetermined shape when inserted into a blood vessel and swells, and the functions of the first surface 41 and the second surface 42 can be performed.

[0050] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made by those skilled in the art within the technical framework of the present invention. In order to make the rate of change P1 of the coefficient of friction Fr1 with respect to changes in load when a load is applied greater than the rate of change P2 of the second surface 42, the material of the covering portion 40 may be different for the first surface 41 and the second surface 42 of the catheter 1.

[0051] The catheter 1 may have a first surface 41 with an uneven shape provided only on a portion of its longitudinal axis. For example, the catheter 1 may have a first surface 41 with a coefficient of friction greater than that of the second surface 42 when unloaded, provided only at the tip of the tube 2. This can suppress the tip of the catheter 1 from slipping at the bifurcation of the blood vessel. To improve passage through narrowed blood vessels, it is preferable that the first surface 41 be formed over a wider area in the longitudinal axis of the catheter 1. [Explanation of Symbols]

[0052] 1 Catheter 2. Body 3 Hubs 4 Kink-resistant protector 5 lumens 10 Inner layer 20 Reinforcement 21 Wire rod 30 outer layer 40 Covered part 41 Page 1 42 Side 2

Claims

1. A catheter comprising a long tubular body having a tip and a base, The aforementioned pipe has a covering portion formed on its outer surface by a low-friction material, The covering portion has a first surface and a second surface that are arranged on opposite sides in the circumferential direction of the pipe, A catheter in which the rate of change of the coefficient of friction of the first surface in response to a change in the load applied to the first surface is greater than the rate of change of the coefficient of friction of the second surface in response to a change in the load applied to the second surface.

2. The first surface has a periodic uneven shape on its surface, The catheter according to claim 1, wherein the second surface is a smooth surface.

3. The catheter according to claim 2, wherein the uneven shape of the first surface has a height difference of 5 μm to 30 μm when swollen, and the spacing in the longitudinal direction of the tube is in the range of 3 mm to 50 mm.

4. The catheter according to any one of claims 1 to 3, wherein the first surface and the second surface are formed at least at the tip of the tube.

5. The catheter according to any one of claims 1 to 3, wherein the coefficient of friction of the first surface under no load is greater than the coefficient of friction of the second surface under no load.

6. The catheter according to any one of claims 1 to 3, wherein the coefficient of friction of the first surface under no load is smaller than the coefficient of friction of the second surface under no load.

7. The catheter according to any one of claims 1 to 3, wherein the covering portion is formed of a hydrophilic polymer that becomes gel-like when swollen.

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