catheter

Abstract

To provide a catheter which not only has a measuring function but also reliably prevents falling of a marker and a positional deviation by a simple structure, and is excellent in safety without risks of hurting a lumen wall.SOLUTION: A medical catheter 10 used by inserting in a lumen of a human body includes a catheter body 11 which has a long tubular shape and is flexible, and where a guide wire can be inserted. On the catheter body 11, an indication means 20 which can measure a length of a peripheral site of an insertion destination under contrast radiography is provided. The indication means 20 comprises a plurality of contrast rings 21 provided side by side in an axial direction along an inner periphery of the catheter body 11.SELECTED DRAWING: Figure 2

Description

Technical Field

[0005]

[0001] The present invention relates to a medical catheter used by being inserted into the body cavity of a human body, and is particularly suitable for a catheter used in a treatment for implanting a stent.

Background Art

[0002] In conventional medicine, as a treatment for cases where the large intestine or the like is blocked due to cancer or the like, a method of inserting a catheter with a guide wire set up to the blocked stenosis site and implanting a stent at the stenosis site is known. Here, it is important to prepare a stent having a length corresponding to the length of the stenosis site, but usually, the length of the stent for implantation is determined on an image such as an X-ray contrast.

[0003] However, the state that can be confirmed on an image such as an X-ray contrast is two-dimensional, and the large intestine to be actually implanted has a three-dimensional curved shape, so the necessary length of the stent could not be accurately measured. In addition, since the core wire itself of the generally used guide wire with a measurer is also metallic, all of the guide wire is imaged. Therefore, it was not suitable as a measurer function.

[0004] Therefore, a technique of adding a measurer function to the catheter body has already been proposed. For example, a technique of attaching a marker made of an X-ray impermeable material to the outer peripheral surface of the catheter body is known (see, for example, Patent Document 1). In addition, a technique is also known in which the catheter body has a multilayer structure, a marker made of an X-ray impermeable material is arranged on the outer peripheral surface of the inner tubular member, and the outer tubular member is covered thereon (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] However, in the technique of attaching markers to the outer surface of the catheter body, there was a risk that the exposed edges of the markers on the outer surface of the catheter body could catch on or damage the lumen wall, and furthermore, the markers were prone to falling off.

[0007] Furthermore, the technique of using a multi-layered catheter body with markers placed between the inner and outer layers not only results in a complex structure and increased costs, but also makes the inner and outer tubular components prone to separation due to the presence of the markers, and the markers themselves are prone to displacement, potentially leading to inaccurate measurements.

[0008] This invention was made in view of the problems of the prior art described above, and aims to provide a catheter that not only has a measuring function but can reliably prevent marker detachment and displacement with a simple structure, and is also safe as there is no risk of damaging the lumen wall. [Means for solving the problem]

[0009] One aspect of the present invention, in order to achieve the above-mentioned objective, In medical catheters used by inserting them into the internal lumen of the human body, It has a long, tubular, flexible catheter body through which a guidewire can be inserted. The catheter body is provided with an indicator means that allows the length of the peripheral portion of the insertion site to be measured under radiographic imaging. The indicator means consists of a plurality of contrast rings arranged axially along the inner circumference of the catheter body. the law of nature, The outer circumference of the contrast ring is provided with irregularities that press against the inner circumference of the catheter body. The aforementioned irregularities consist of a plurality of annular protrusions provided continuously in the axial direction along the outer circumference of the contrast ring, and recesses between the plurality of protrusions. The portions where the multiple protrusions press against the inner circumference of the catheter body are arranged in a continuous axial direction as convex portions, where the outer circumference of the catheter body is raised convexly from its reference plane. It is characterized by the following: [Effects of the Invention]

[0010] The catheter according to the present invention not only has a measuring function, but also has a simple structure that can reliably prevent marker detachment and displacement, and is safe as there is no risk of damaging the lumen wall. [Brief explanation of the drawing]

[0011] [Figure 1] This is a plan view showing the entire catheter according to an embodiment of the present invention. [Figure 2] This is a plan view showing an enlarged view of the main part of a catheter according to an embodiment of the present invention. [Figure 3] This is a cross-sectional view taken along line III-III in Figure 2. [Figure 4] This is a plan view showing a magnified portion of the catheter body equipped with a contrast ring, as shown in the modified example. [Figure 5] Figure 4 is a cross-sectional view along the VV line. [Modes for carrying out the invention]

[0012] Hereinafter, a representative embodiment of the present invention will be described based on the drawings. The catheter 10 according to this embodiment is a medical device used by being inserted into the lumen of the human body. The following description will use the catheter 10 in a treatment example where it is used to place a stent in a narrowed area, for example, when the large intestine or other part of the body is obstructed due to cancer. The components, shapes, numerical values, etc., shown in the embodiments described below are merely examples of the present invention and do not limit the present invention.

[0013] <Overview of Catheter 10> As shown in FIG. 1, the catheter 10 includes a catheter body 11 that is long, tubular, and flexible and through which a guide wire (not shown) can be inserted. At the distal end side (the left side in FIG. 1) of the catheter body 11, index means 20 capable of measuring the length of the peripheral part of the insertion tip under fluoroscopy is provided. Here, the peripheral part is, for example, a stenotic part in the large intestine. On the other hand, a connector 30 is provided at the proximal end side (the right side in FIG. 1) of the catheter body 11. In each figure, a part of the catheter body 11 is partially omitted.

[0014] <Catheter body 11> As shown in FIG. 1, the catheter body 11 is an elongated, long tube shape, and although it shows a curved state in an inverted S shape in FIG. 1, it has flexibility that allows it to be extended straight overall or curved freely. The material of the catheter body 11 is suitable for flexible synthetic resins such as fluororesin, silicone rubber, polyurethane, and soft polyvinyl chloride, for example. These materials of the catheter body 11 are all transparent or translucent and can be visually recognized through the inside.

[0015] The inside of the catheter body 11 serves as a lumen 12 (see FIG. 3) for inserting a guide wire or introducing a contrast agent or the like. Also, an endoscope may be configured to be inserted into the lumen 12 of the catheter body 11. The tip of the lumen 12 of the catheter body 11 opens outside the tip of the catheter body 11, and the base end of the lumen 12 communicates with the inside of a connector 30 described later.

[0016] As shown in FIG. 2, in the catheter body 11, a section about 200 mm from its tip is formed to have a slightly smaller diameter through a diameter-reducing portion 13 that gradually reduces in diameter from the reference outer diameter at the proximal end. Here, the portion with a smaller diameter on the tip side of the diameter-reducing portion 13 is formed by a drawing manufacturing method when providing the index means 20 described below. Further, the foremost end portion 14 of the catheter body 11 is formed to have an even smaller diameter and is designed to easily pass through a stenotic site such as the large intestine. Note that the overall length of the catheter body 11 is a design matter that can be determined as appropriate.

[0017] <index means 20> As shown in FIGS. 2 and 3, the index means 20 has a measuring function capable of measuring the length of the peripheral site that is the insertion tip of the catheter body 11, and is provided in the lumen 12 of the catheter body 11. That is, the index means 20 is composed of a plurality of contrast rings 21 arranged axially along the inner circumference of the catheter body 11. The contrast ring 21 is configured as a separate body from the catheter body 11, but is integrally crimped to the inner circumference of the catheter body 11 by a drawing manufacturing method.

[0018] <<contrast ring 21>> The contrast ring 21 is formed into a thin ring or tube shape from a radiation-impervious material that can be visually recognized under radiation contrast such as X-rays. Here, as the radiation-impervious material, for example, tungsten, tantalum, platinum (iridium), etc. are suitable. The axial width of the contrast ring 21 is set to, for example, 1 to 3 mm, and the outer diameter of the contrast ring 21 is set to be substantially equal to the inner diameter of the catheter body 11. Here, if the width of the contrast ring 21 exceeds 3 mm and becomes too long, the flexibility and curvature followability of the tip side of the catheter body 11 where the index means 20 is located will be impaired, and problems may occur in operability. Conversely, if the width of the contrast ring 21 is less than 1 mm, it will be too fine to be easily visually recognized as a scale.

[0019] The contrast ring 21 of this embodiment has two different configurations: a contrast ring 21A with a width of 3 mm and a contrast ring 21B with a width of 1 mm, arranged in a repeating alternation pattern. Furthermore, it is preferable to color the contrast rings 21A and 21B in different colors. For this coloring, one may be the base color of the material, while the other is colored in a contrasting color such as black or navy blue. The actual coloring is done by directly applying paint or by coating, so that the color separation is visible not only under X-ray contrast but also under endoscopic observation. Hereinafter, when referring to both the contrast ring 21A and 21B collectively, they will simply be referred to as the contrast ring 21.

[0020] Multiple contrast rings 21 are arranged at equal axial intervals along the inner circumference of the tip section of the catheter body 11. The spacing between each contrast ring 21 should be set to, for example, 10 mm. If the spacing between each contrast ring 21 is less than 10 mm, the flexibility and bending followability of the tip section of the catheter body 11 may be impaired, potentially causing problems with operability. Conversely, if the spacing between each contrast ring 21 exceeds 10 mm, it becomes impossible to measure length precisely and accurately. The contrast rings 21 should be arranged widely within the tip section of the catheter body 11, for example, from the tip of the proximal end 14 to the proximal end, up to about 20 cm.

[0021] The contrast rings 21 are attached and positioned, for example, by a drawing method. Specifically, each contrast ring 21 is placed at equal intervals on the core, and then the core is inserted into the lumen 12 of the tip section of the catheter body 11 and heated to a high temperature. This causes the fluororesin or other material of the catheter body 11 to shrink due to the heat, allowing each contrast ring 21 to be pressed against the inner circumference of the catheter body 11. After that, the core can be removed from the lumen 12 of the catheter body 11.

[0022] According to this drawing method, as mentioned above, the smaller diameter portion of the catheter body 11 towards the tip of the reduced diameter portion 13 can be formed simultaneously. If the outer diameter of the catheter body 11 at the point where the contrast ring 21 overlaps is slightly convex compared to its reference surface, then irregularities will be created on the outer circumference of the catheter body 11. If these irregularities reduce the contact area between the outer circumference of the catheter body 11 and the inner wall of the body cavity, the sliding properties of the catheter body 11 can be improved.

[0023] Furthermore, although Figure 3 does not show the details of the contrast ring 21, as shown in Figure 5, which relates to a modified example of the contrast ring 21 described below, one end edge of the contrast ring 21 facing the proximal end of the catheter body 11 is provided with a tapered portion 22 that slopes from the outer circumference to the inner circumference toward the tip of the catheter body 11. This tapered portion 22 gives one end edge of the contrast ring 21 a funnel shape, making it easy for the guidewire inserted from the proximal end of the catheter body 11 to pass through without getting caught on the contrast ring 21.

[0024] <<Contrast Ring 21C>> Figures 4 and 5 show a modified contrast ring 21C of the contrast ring 21. The contrast ring 21C has basically the same configuration as the contrast ring 21, but the outer circumference of the contrast ring 21C is provided with irregularities that press against the inner circumference of the catheter body 11. Note that in Figure 4, only the outer surface of the catheter body 11 is shown without showing the contrast ring 21C inside the catheter body 11. Also, the boundary between the convex portion 15, which will be described later, and the reference surface of the outer circumference of the catheter body 11 is schematically shown as approximately a right angle in Figure 4, but in reality it is a gentle curved shape.

[0025] More specifically, the irregularities on the outer circumference of the contrast ring 21C consist of a plurality of annular protrusions 23 provided axially along the outer circumference of the contrast ring 21C, and recesses 24 between the plurality of protrusions 23. Here, the areas where the protrusions 23 press against the inner circumference of the catheter body 11 are convex portions 15 on the outer circumference of the catheter body 11, as shown in Figure 4. Such irregularities improve the fixation of the contrast ring 21C to the inner circumference of the catheter body 11.

[0026] <Connector 30> As shown in Figure 1, a connector 30 is provided at the proximal end of the catheter body 11, which is connected to the lumen 12. The connector 30 is bifurcated and comprises a main trunk 31 that extends coaxially with the catheter body 11 and communicates with the lumen 12, and a branched portion 32 that branches off from the main trunk 31 and communicates with the lumen 12 together with the main trunk 31.

[0027] The main trunk 31 has a guidewire insertion port 33 that communicates with the lumen 12. The branching portion 32 also has a contrast agent injection port 34 that communicates with the lumen 12. The guidewire insertion port 33 may be formed with a diameter that allows insertion of a small-diameter endoscope. Although not shown in the figure, an annular member made of, for example, silicone is installed inside the main trunk 31. This annular member functions as a packing to prevent leakage of contrast agent from the guidewire insertion port 33. The connector 30 is formed separately from the catheter body 11, and its material is suitable, for example, polyacetal.

[0028] <Function of Catheter 10> Next, the operation of the catheter 10 according to this embodiment will be described. When using catheter 10, a guidewire is set in the lumen of the catheter body 11. In some cases, the guidewire may be inserted first to the narrowed area of ​​the large intestine that is causing the obstruction.

[0029] The catheter body 11, with the guidewire attached, is inserted, for example, through the forceps channel of an endoscope. The catheter body 11 is then guided along the guidewire to the narrowed area of ​​the large intestine that is causing the obstruction. Once the leading edge 14 of the catheter body 11 reaches the narrowed area, contrast agent is injected through the contrast agent injection port 34 of the connector 30, and the condition of the narrowed area is confirmed under X-ray fluoroscopy.

[0030] Subsequently, with the leading edge 14 of the catheter body 11, along with the guidewire, pushed all the way to the end of the narrowed area, the length of the narrowed area is measured using the indicator means 20 of the catheter body 11. The indicator means 20 has multiple contrast rings 21 arranged at equal intervals on the inner circumference of the catheter body 11, and acts as a measuring tape for measuring the length of the narrowed area of ​​the large intestine under X-ray contrast, allowing for accurate measurement of the length of the narrowed area.

[0031] Based on the measurement results of the stenosis using the indicator 20, a stent of a size appropriate to the length of the stenosis is selected and placed in the stenosis using the catheter body 11. After stent placement, contrast agent is injected again from the catheter body 11 to confirm that the stenosis has been dilated by the stent.

[0032] The contrast ring 21 of the indicator means 20 is provided along the inner circumference of the catheter body 11, rather than on the outer circumference of the catheter body 11 as in conventional technology, and is therefore not exposed to the outside of the catheter body 11. Consequently, there is no risk of the contrast ring 21 getting caught on or damaging the lumen wall, and there is also no risk of it falling off or becoming displaced. The contrast ring 21 with such a simple structure can be easily placed on the inner circumference of the catheter body 11 by a drawing method, resulting in excellent productivity and cost reduction.

[0033] Furthermore, the contrast ring 21 is not only radiopaque, but in this embodiment, two different forms (contrast ring 21A and contrast ring 21B) are arranged alternately, making them easy to distinguish visually and facilitating measurement as a measuring tool. In particular, since the contrast ring 21 is color-coded in two colors, while in conventional technology the markers visible on the endoscope monitor and the markers visible visually and under endoscopic observation were separate, the contrast ring 21 alone can provide both visibility.

[0034] In this embodiment, one of the contrast rings 21, contrast ring 21A, has a width of 3 mm and is made of a metal such as tungsten, while the other contrast ring 21B is shorter, with a width of 1 mm, and is colored black. Both contrast rings 21 have a width of 3 mm or less, and are spaced 10 mm apart from each other. This ensures that the flexibility and bending-following ability of the tip of the catheter body 11, which has the indicator means 20, is not impaired, allowing for easy operation and accurate measurement of the length of the narrowed portion of the large intestine.

[0035] Furthermore, the tip of the catheter body 11 on which the contrast ring 21 is placed is thinner than the standard outer diameter of the catheter body 11 due to the drawing method, making it more flexible and improving operability. The section on which such indicator means 20 is provided only needs to be within a range of about 20 cm from the tip of the leading edge 14 towards the proximal end, which is sufficient to accommodate the length of many stenotic areas that may occur in the large intestine. The contrast ring 21 closest to the tip of the leading edge 14 may be set to be longer than the width of the other contrast rings 21.

[0036] As mentioned above, according to the drawing method, although not shown in Figure 3, the outer diameter of the catheter body 11 at the point where the contrast ring 21 overlaps the inner circumference of the catheter body 11 will be slightly convex and raised from its reference plane. As a result, in the section where the indicator means 20 is located, irregularities are created on the outer circumference of the catheter body 11, which reduces the contact area between the outer circumference of the catheter body 11 and the inner wall of the body cavity, thereby improving the sliding properties of the catheter body 11.

[0037] Furthermore, the edge of the contrast ring 21 facing the proximal end of the catheter body 11 is provided with a tapered portion 22 (see Figure 5) that slopes from the outer circumference to the inner circumference toward the tip of the catheter body 11. In this way, the proximal end of the contrast ring 21 is funnel-shaped due to the tapered portion 22, so it does not obstruct the advancement of the guidewire inserted from the proximal end of the catheter body 11, and the guidewire can be manipulated smoothly.

[0038] If the proximal end of the contrast ring 21 were flared outward, the outer diameter of the flared edge would be larger than the outer diameter of the contrast ring 21. Therefore, if the catheter body 11 is thin, the portion overlapping the flared edge would protrude excessively, potentially creating resistance to other medical devices used in conjunction with the catheter 10. Furthermore, the flared edge could potentially puncture or damage the catheter body 11. On the other hand, in this embodiment, the contrast ring 21 is funnel-shaped due to the tapered portion 22. Therefore, even if the catheter body 11 is thin, its outer surface will not protrude excessively, and the risk of damage is low.

[0039] Furthermore, as shown in Figure 5, by providing annular protrusions 23 and recesses 24 between them on the outer circumference of the contrast ring 21C as irregularities that press against the inner circumference of the catheter body 11, the fixation of the contrast ring 21C to the inner circumference of the catheter body 11 can be improved. In particular, the portion where the protrusions 23 of the contrast ring 21C press against the inner circumference of the catheter body 11 is raised as a convex portion 15 on the outer circumference, as shown in Figure 4.

[0040] As a result, as mentioned above, the outer diameter of the catheter body 11 is slightly convex above its reference surface across the entire width of the contrast ring 21, and even finer convex portions 15 are continuously present within the width range of each individual contrast ring 21. Therefore, the contact area between the outer circumference of the catheter body 11 and the inner wall of the large intestine, etc., is further reduced, and the sliding properties of the catheter body 11 can be further improved.

[0041] <Construction and Effects of the Invention> Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above. The present invention derived from the embodiments described above will be described below.

[0042] First, the present invention relates to a medical catheter 10 used by being inserted into the lumen of the human body, The catheter body 11 is long, tubular, flexible, and allows a guidewire to be inserted. The catheter body 11 is provided with an indicator means 20 that can measure the length of the peripheral portion of the insertion site under radiographic imaging. The indicator means 20 is characterized by comprising a plurality of contrast rings 21 arranged axially along the inner circumference of the catheter body 11.

[0043] Such a catheter 10 not only has a measuring function using an indicator means 20, but also has a simple configuration with contrast rings 21 arranged in a row, and in particular, by providing the contrast rings 21 on the inner circumference of the catheter body 11, it is possible to reliably prevent the contrast rings 21 from falling off or shifting position, and it is also safe as there is no risk of damaging the inner lumen wall.

[0044] Furthermore, in the present invention, the plurality of contrast rings 21 are arranged at equal intervals in the axial direction along the inner circumference of the distal tip section of the catheter body 11. The contrast ring 21 is characterized in that its axial width is set to 1 to 3 mm, and the spacing between each contrast ring 21 is set to 10 mm.

[0045] This configuration ensures that the flexibility and bending-following ability of the tip section of the catheter body 11, where the indicator means 20 is located, is not compromised, allowing the catheter 10 to be easily manipulated. Furthermore, it enables more accurate measurement of the length of the surrounding area beyond the insertion point of the tip of the catheter body 11.

[0046] Furthermore, the present invention is characterized in that a tapered portion 22 is provided on the edge of the contrast ring 21 facing the proximal end side of the catheter body 11, which is the proximal end side of the catheter body 11, and the tapered portion 22 slopes from the outer circumference to the inner circumference toward the distal end side of the catheter body 11.

[0047] With this configuration, the proximal end of the contrast ring 21 is funnel-shaped due to the tapered portion 22, so it does not obstruct the advancement of the guidewire inserted from the proximal end of the catheter body 11, and the guidewire can be manipulated smoothly.

[0048] Furthermore, in the present invention, the plurality of contrast rings 21 are formed in at least two different shapes, and these two different shapes are arranged repeatedly and alternately. Here, different forms of the contrast ring 21 include, for example, differences in axial width or different color coding. It should be noted that it is not necessary for all contrast rings 21 to be arranged alternately in different forms; at least some of the indicator means 20 may be arranged so that they are arranged alternately in different forms.

[0049] In this way, by arranging contrast rings 21 of different shapes (contrast ring 21A and contrast ring 21B) alternately in a repeated pattern, individual contrast rings 21 are easily identifiable visually, making measurement as a measuring tool easier. This makes it possible to more accurately measure the length of the surrounding area of ​​the insertion site, such as a narrowed area of ​​the large intestine.

[0050] Furthermore, the present invention is characterized in that the outer circumference of the contrast ring 21C is provided with irregularities that press against the inner circumference of the catheter body 11. This configuration improves the fixation of the contrast ring 21C to the inner circumference of the catheter body 11.

[0051] Furthermore, in the present invention, the irregularities consist of a plurality of annular protrusions 23 provided axially along the outer circumference of the contrast ring 21C, and recesses 24 between the plurality of protrusions 23. The portion where the protrusion 23 presses against the inner circumference of the catheter body 11 is characterized in that the outer circumference of the catheter body 11 forms a convex portion 15 that is raised convexly from its reference plane.

[0052] This configuration makes it possible to more reliably improve the fixation of the contrast ring 21C to the inner circumference of the catheter body 11. Moreover, since the portion where the convex portion 23 of the contrast ring 21C presses against the inner circumference of the catheter body 11 is raised as a convex portion 15 on the outer circumference, the contact area between the outer circumference of the catheter body 11 and the inner wall of the body cavity is reduced, thereby improving the sliding properties of the catheter body 11.

[0053] Although embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to the embodiments described above, and any changes or additions that do not depart from the spirit of the present invention are also included. For example, the specific shapes and relative sizes of the catheter body 11, indicator means 20, and contrast ring 21 are not limited to those shown in the drawings. Furthermore, the catheter 10 is not limited to the treatment of placing a stent in the narrowed area of ​​the colon that is obstructing it, as described above, but can be applied to catheters for various other purposes.

[0054] Furthermore, the width of the contrast ring 21 itself in the indicator means 20, and the spacing between each contrast ring 21 are design items that can be determined as appropriate. For example, a contrast ring 21A (2 mm wide) and a contrast ring 21B (1 mm wide) may be placed at 10 mm intervals in a section approximately 50 mm from the tip of the catheter body 11. [Industrial applicability]

[0055] The catheter according to the present invention is not limited to use in the treatment of placing a stent in a narrowed area of ​​the large intestine that is causing obstruction, but can be applied to catheters for various other purposes. [Explanation of symbols]

[0056] 10…Catheter 11…Catheter body 12...lumen 13...Reduced diameter part 14...Cutting edge part 15…Convex part 20…Indicator means 21A...Contrast ring 21B...Contrast ring 21C...Contrast ring 22... Tapered section 23…Convex part 24…recess 30… Connector 31…Main executive 32... Branching point 33… Guidewire insertion port 34…Contrast agent injection port

Claims

1. In medical catheters used by inserting them into the internal lumen of the human body, It has a long, tubular, flexible catheter body through which a guidewire can be inserted. The catheter body is provided with an indicator means that allows the length of the peripheral portion of the insertion site to be measured under radiographic imaging. The indicator means consists of a plurality of contrast rings arranged axially along the inner circumference of the catheter body. The outer circumference of the contrast ring is provided with irregularities that press against the inner circumference of the catheter body. The aforementioned irregularities consist of a plurality of annular protrusions provided continuously in the axial direction along the outer circumference of the contrast ring, and recesses between the plurality of protrusions. The catheter is characterized in that the portions in which the plurality of protrusions press against the inner circumference of the catheter body are convex portions that are raised convexly from the reference plane on the outer circumference of the catheter body and are arranged continuously in the axial direction.

2. The plurality of contrast rings are arranged at equal intervals in the axial direction along the inner circumference of the distal tip section of the catheter body. The catheter according to claim 1, characterized in that the axial width of the contrast ring is set to 1 to 3 mm, and the distance between each contrast ring is set to 10 mm.

3. The catheter according to claim 2, characterized in that the edge of the contrast ring facing the proximal end of the catheter body is provided with a tapered portion that slopes from the outer circumference to the inner circumference toward the distal end of the catheter body.

4. The catheter according to claim 3, characterized in that the plurality of contrast rings are formed in at least two different shapes, and the two different shapes are repeatedly arranged alternately.

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