JP2020171787A - Stent delivery catheter - Google Patents

Abstract

To provide a stent delivery catheter with a new structure capable of placing a stent by uniform diameter reduction when a stent with many waves is to be set on a balloon.SOLUTION: A balloon 12 is set at the distal end part of a shaft 24, a stent 14 is set on the balloon 12, and the stent 14 has a skeletal structure extending in a circumferential direction by folding in an axial direction concerning a stent delivery catheter 10. A large diameter part 42 having an outer diameter dimension larger than that of a proximal end side adjacent part 40 in a placement portion is arranged in the placement portion of the stent 14 in the shaft 24.SELECTED DRAWING: Figure 3

Description

The present invention relates to a stent delivery catheter for delivering a stent to a stenotic site in a lumen, and more particularly to a stent delivery catheter for delivering a stent having a large number of waves.

Conventionally, when an abnormality such as stenosis or occlusion occurs in a lumen such as a blood vessel, a stent is delivered to a lesion in the lumen by, for example, a stent delivery catheter. Then, by expanding the stent and pressing it against the lumen wall, stent treatment for keeping the lumen in an expanded state is performed. The stent has a small diameter when inserted into the lumen, but is expanded and placed in the lumen. As a method of expanding the diameter of the stent in the lumen, there are expansion by a balloon, in addition to self-expansion and mechanical expansion by a shape memory material or the like.

That is, when the stent is expanded by a balloon, it is extrapolated with the balloon folded with respect to the tip portion of the shaft, as in the stent delivery catheter described in Japanese Patent Application Laid-Open No. 2014-61191 (Patent Document 1). Along with the attachment, a stent is extrapolated and attached to the folded balloon to reduce the diameter. Then, the tip portion of the stent delivery catheter is inserted into the lesion portion in the lumen to expand the balloon, so that the stent extrapolated to the balloon is expanded in diameter and pressed against the lumen wall. The stent is then placed in the lumen by contracting the balloon and removing the catheter.

By the way, as the stent to be placed in the lumen, for example, a stent having a skeleton in which one linear body is continuously extended in a spiral or tubular shape in the circumferential direction while being folded back in the axial direction is adopted. As such a stent, for example, when it is placed in a thick lumen or the like, a stent having a large wave number (number of bent portions) in the circumferential direction and widely expanding when the diameter is expanded is preferably adopted.

On the other hand, the balloon attached to the tip portion of the stent delivery catheter is preferably a balloon having a small film thickness in order to secure the flexibility of the tip portion of the catheter.

However, since the outer diameter of a balloon having a small film thickness becomes small when folded, there is a risk that the stent may not be uniformly reduced in diameter when a stent having a large wave number is extrapolated and subjected to diameter reduction treatment. Specifically, there was a risk that adjacent struts in the circumferential direction of the stent would partially overlap. In addition, this may cause a problem that the stent does not expand uniformly when the balloon is expanded to expand the diameter of the stent.

Japanese Unexamined Patent Publication No. 2014-61191

The present invention has been made in the background of the above circumstances, and the problem to be solved is to uniformly reduce the diameter of the stent even when the stent is attached to the balloon, particularly when the stent having a large wave number is attached. It is an object of the present invention to provide a stent delivery catheter having a novel structure that can be attached to the stent.

Hereinafter, aspects of the present invention made to solve such problems will be described. The components adopted in each of the following aspects can be adopted in any combination as much as possible.

In the first aspect of the present invention, a balloon is attached to the tip of the shaft, and a stent is attached to the balloon, and the stent has a turn portion curved in a substantially arc shape and is folded back in the axial direction. In a stent delivery catheter having a skeletal structure extending in a direction, the mounting portion of the stent on the shaft has a larger outer diameter than the proximal end side adjacent portion of the mounting portion, and the stent is provided. It is characterized in that a large-diameter portion is provided so that adjacent portions in the circumferential direction do not overlap each other and are folded back more than 180 degrees at the folded turn portion so as to be in a mounted state.

According to the stent delivery catheter having a structure according to this embodiment, since a large diameter portion is provided in the stent mounting portion on the shaft, the outer diameter of the balloon at the time of folding can be set regardless of the thickness of the balloon. It is possible to set appropriately by the outer diameter dimension of the large diameter part. As a result, for example, even if a balloon having a thin film thickness and a stent having a large wave number are used at the same time, it is possible to prevent the outer diameter of the balloon when folded from becoming too small as compared with the inner diameter of the stent when the diameter is reduced. Therefore, even when the stent is reduced in diameter and mounted on the balloon, uneven diameter reduction such as excessive diameter reduction of the stent and overlapping struts can be effectively avoided.

A second aspect of the present invention is the stent delivery catheter according to the first aspect, wherein the outer diameter dimension of the large diameter portion is such that a covering member is attached to the outer peripheral surface of the shaft body. It is made larger than the outer diameter dimension of the adjacent portion on the proximal end side of the mounting portion in the main body.

According to the stent delivery catheter having a structure according to this embodiment, the outer diameter dimension of the large diameter portion is the proximal end of the stent mounting portion on the shaft body by mounting the covering member on the outer peripheral surface of the shaft body. Since it is larger than the outer diameter of the side adjacent portion, the large diameter portion can be formed with a simple structure.

In the third aspect of the present invention, in the stent delivery catheter according to the second aspect, the hardness of the covering member is made smaller than the hardness of the shaft body.

According to the stent delivery catheter having a structure according to this embodiment, since the hardness of the covering member is smaller than the hardness of the shaft body, flexibility at the tip portion of the stent delivery catheter can be satisfactorily secured. The material of the covering member is not limited in any way, but synthetic resins such as polyamide elastomer, polyester elastomer, and polyurethane can be preferably used.

As the shape of the large diameter portion of the stent delivery catheter according to the present invention, for example, the following aspects can be preferably adopted. That is, the fourth aspect of the present invention is the stent delivery catheter according to any one of the first to third aspects, wherein the outer diameter dimension of the large diameter portion is constant throughout. Is.

According to the stent delivery catheter having a structure according to this aspect, since the outer diameter dimension of the large diameter portion is constant throughout, the support surface of the folded balloon is regarded as the circumferential surface and is supported. The surface area can be secured more stably. In the large-diameter portion of this embodiment, for example, when the shaft is manufactured, the stent mounting portion is uniformly thickened, a synthetic resin material is applied to the tip portion of the shaft, or a tubular member is used for the shaft. It can be formed by a simple means such as extrapolation and mounting on the.

A fifth aspect of the present invention is the stent delivery catheter according to any one of the first to third aspects, wherein the outer diameter dimension of the large diameter portion is partially different.

According to the stent delivery catheter having a structure according to this embodiment, the outer diameter dimension of the large diameter portion is partially different, and the degree of freedom in the structure and manufacture of the large diameter portion can be expanded. Specifically, for example, the large-diameter portion may have a shape that extends spirally in the circumferential direction with respect to the shaft, or a plurality of ridges are provided at a predetermined distance in the axial direction or the circumferential direction. Such a shape or a structure in which a mesh-like convex portion is provided on the outer peripheral surface of the shaft may be used.

A sixth aspect of the present invention is the stent delivery catheter according to the fifth aspect, wherein the large diameter portion has a stent position in which the outer diameter dimension is larger than that of the other portion in the axial direction in the large diameter portion. The specified portion is partially provided in the axial direction.

According to the stent delivery catheter having a structure according to this aspect, since the stent positioning portion having a larger outer diameter dimension is partially provided in the large diameter portion of the shaft in the axial direction, the stent positioning portion is provided. In, the stent is positioned and mounted on the shaft with a stronger holding force to prevent the stent from falling off the shaft. Moreover, by making the shaft side a large diameter, it is not necessary to significantly reduce the diameter of the stent in order to obtain a strong holding force, and the overlapping of struts is avoided when the diameter is reduced, and the diameter of the stent can be expanded stably. Will be done.

Further, when the diameter of the stent extrapolated to the shaft and the balloon is reduced, the inner diameter of the stent may be smaller than the outer diameter of the stent positioning portion in the region where the stent deviates from the stent positioning portion of the large diameter portion. According to this, since the stent is axially locked to the stent positioning portion and the stent is positioned axially with respect to the shaft, it is possible to further prevent the stent from falling off from the shaft. ..

A seventh aspect of the present invention is the stent delivery catheter according to any one of the first to sixth aspects, wherein the shaft is provided with a guide wire lumen through which a guide wire is inserted.

According to the stent delivery catheter having a structure according to this embodiment, the catheter can be easily guided to the lesion along the guide wire. In particular, since the shaft is provided with guide wire lumens, structural complications can be avoided. The stent delivery catheter according to the present invention may be a rapid exchange type catheter or an over-the-wire type catheter. Further, the eighth aspect of the present invention has a skeletal structure extending in the circumferential direction while being folded back in the axial direction with a turn portion curved in a substantially arc shape, and in a mounted state extrapolated to the shaft, in the circumferential direction. It features a stent in which adjacent portions do not overlap each other and are folded more than 180 degrees at the folded turn.

According to the stent delivery catheter having a structure according to the present invention, since a large diameter portion is provided in the stent mounting portion on the shaft, the outer diameter of the balloon at the time of folding can be greatly adjusted and set. As a result, uneven diameter reduction of the stent mounted on the balloon can be avoided, and the stent can be stably mounted.

The front view which shows the whole of the stent delivery catheter as the 1st Embodiment of this invention. The front view which shows the main part of the stent delivery catheter shown in FIG. 1 in an enlarged manner. FIG. 2 is a vertical cross-sectional view of a main part of the stent delivery catheter shown in FIG. An enlarged view of the IV-IV cross section of FIG. It is a figure which shows a specific example of the stent which can be adopted in this invention, and is the development view which opened at one place in the circumferential direction. The vertical sectional view which shows the large diameter part of the shaft in the stent delivery catheter as the 2nd Embodiment of this invention. The vertical sectional view of the main part in the stent delivery catheter as the 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, FIGS. 1 to 4 show a stent delivery catheter (hereinafter, catheter) 10 as a first embodiment of the present invention. A balloon 12 is attached to the tip of the catheter 10, and a stent 14 is extrapolated to the balloon 12. Then, the stent 14 is delivered and placed in the narrowed portion of the lumen such as a blood vessel by the catheter 10, so that the narrowed portion of the lumen is maintained in an expanded state. In the following description, the proximal end side refers to the right side in FIG. 1 where the user operates the catheter 10, and the distal end side is a diagram which is far from the user during use. Say the left side of 1. Further, the axial direction refers to the left-right direction in FIG. 1, which is the length direction of the catheter 10.

More specifically, the catheter 10 of the present embodiment has a structure in which the connector 18 is provided on the proximal end side of the catheter body 16. The catheter body 16 is configured by connecting the distal shaft 20 on the distal end side and the proximal shaft 22 on the proximal end side in the axial direction.

The proximal shaft 22 has a single-tube structure extending in the axial direction, and is formed of, for example, a synthetic resin such as a polyamide elastomer or a metal such as stainless steel. The proximal end of the proximity shaft 22 is connected to the connector 18, and the lumen of the proximity shaft 22 is communicated to the external space through the connector 18.

On the other hand, the distal shaft 20 has a double pipe structure of an inner shaft 24 and an outer shaft 26 as a shaft as a whole. The inner shaft 24 includes an inner shaft main body 28, and the outer diameter dimension of the inner shaft main body 28 is smaller than the inner diameter dimension of the outer shaft 26. Further, the proximal end of the inner shaft body 28 is inserted into the outer shaft 26, and the distal end of the inner shaft body 28 protrudes from the distal end of the outer shaft 26.

Here, the outer shaft 26 has a tubular shape extending in the axial direction, and is formed of a synthetic resin such as a polyamide elastomer. The outer diameter of the outer shaft 26 is substantially equal to that of the proximity shaft 22, and the proximal end of the outer shaft 26 and the distal end of the proximity shaft 22 are connected. As a result, the lumen of the outer shaft 26 and the lumen of the proximal shaft 22 are communicated with each other.

Further, the inner shaft main body 28 has a tubular shape extending in the axial direction as a whole, and is formed of a synthetic resin such as a polyamide elastomer. A tip tip 30 is fixed to the distal end of the inner shaft body 28. The tip 30 has a cylindrical shape and has substantially the same outer diameter as the inner shaft body 28. On the other hand, the proximal end of the inner shaft body 28 is bent and opens on the outer peripheral surface of the outer shaft 26. As a result, the lumen of the inner shaft body 28 is a lumen that opens at the tip of the catheter 10 and the intermediate portion in the axial direction, and this lumen is a guide wire lumen through which a guide wire for guiding the catheter 10 is inserted. It is 32. That is, the catheter 10 of the present embodiment is a rapid exchange type catheter in which the guide wire lumen is shorter than the total length in the axial direction of the catheter.

A balloon 12 is attached to the tip of the inner shaft 24 having such a structure. The balloon 12 can be expanded and contracted by introducing and discharging a fluid inside, and is a tubular or bag-shaped member formed of a thin-film synthetic resin, a rubber film, or the like. The material of the balloon 12 is not limited in any way, but in the present embodiment, the balloon 12 is made of nylon resin, and the balloon 12 is subjected to the pressure applied when the fluid is supplied to the inside and expanded. It is said to be a low compliant balloon with a small change in outer diameter. Further, in order to suppress the influence on the flexibility of the inner shaft 24, it is desirable that the balloon 12 is made as thin as possible while ensuring the strength capable of expanding the diameter of the stent 14 described later at the time of expansion.

The distal end of the balloon 12 is fixed to the distal end of the inner shaft body 28 and the outer peripheral surface of the tip tip 30 by adhesion or the like, while the proximal end of the balloon 12 is the outer periphery of the distal end of the outer shaft 26. It is fixed to the surface by adhesion or the like. Therefore, the space between the inner shaft main body 28 and the outer shaft 26 in the radial direction is communicated with the internal space of the balloon 12, while being communicated with the external space through the proximal shaft 22. As a result, fluid can be introduced and discharged from the external space into the internal space of the balloon 12 through the space between the inner shaft body 28 and the outer shaft 26 in the radial direction, and from the internal space of the balloon 12 to the external space. The entire cavity is a supply / discharge lumen 33 that supplies / discharges fluid to / from the balloon 12.

Further, substantially cylindrical markers 34 and 34 are extrapolated on the outer peripheral surfaces of the inner shaft main body 28 at both ends in the axial direction of the balloon 12. These markers 34, 34 are made of a material such as platinum, which is opaque to X-rays.

As shown in FIG. 4, the balloon 12 in the initial state is in a wrapping state in which the balloon 12 is folded in the circumferential direction so as to overlap in the radial direction.

A substantially tubular stent 14 extending in the axial direction as a whole is extrapolated and attached to the balloon 12. The shape of the stent is not limited as long as it has a skeletal structure that extends in the circumferential direction while being folded back in the axial direction, but the stent 14 of the present embodiment is shown in FIG. 5 as a specific example. As shown, one linear body 36 has a skeletal structure that reciprocates in the axial direction with a substantially constant amplitude and extends spirally in the circumferential direction as a whole. In particular, it is preferable that the number of waves in the circumferential direction in one round, that is, the number of repeating units of the periodic structure in one round of the linear body 36 is 10 to 12, which is larger than that of a general coronary stent. In the form of the stent 14, it is 12 waves. The material of the stent is not limited in any way, but the stent 14 of the present embodiment is formed of a cobalt-chromium alloy. As shown in FIG. 2, in the stent 14, one linear body 36 constitutes a plurality of annular bodies 38, and the plurality of annular bodies 38 are arranged in parallel in the axial direction. It has a structure, and the annular bodies 38, 38 adjacent to each other in the axial direction may be connected and reinforced at appropriate points in the circumferential direction.

By adopting a stent having a larger wave number than a general stent as described above, the diameter of the stent can be further expanded at the time of diameter expansion, and it becomes possible to handle, for example, a thicker lumen or a branched lumen. .. Further, since the wave number is large, the surface area of the linear body 36 can be increased, and when it is used as a drug-eluting stent (DES), the amount of the drug applied to the surface of the linear body 36 is increased. Can be made to.

In the initial state, the stent 14 is extrapolated and attached to the balloon 12 as shown in FIG. 2 and the like by mechanically reducing the diameter.

Here, the mounting portion of the stent 14 on the inner shaft 24 is provided with a large diameter portion 42 having an outer diameter larger than that of the proximal end side adjacent portion 40 of the mounting portion. In the present embodiment, in the mounting portion of the stent 14, the covering member 44 is mounted on the outer peripheral surface of the inner shaft main body 28, so that the outer diameter dimension is larger than that of the proximal end side adjacent portion 40 of the mounting portion of the stent 14. A large diameter portion 42 having a large diameter is configured. Further, in the present embodiment, the inner shaft 24 is composed of the inner shaft main body 28 and the covering member 44.

The covering member 44 has a substantially tubular shape extending in the axial direction, and in the present embodiment, the covering member 44 has an axial dimension substantially the same as or slightly larger than the axial dimension of the stent 14, and the total length in the axial direction. It has a substantially constant outer diameter dimension. That is, in the present embodiment, the outer diameter dimension of the large diameter portion 42 is substantially constant throughout. Then, on the outer peripheral side of the covering member 44, the stent 14 is mounted on the balloon 12. The material of the covering member 44 is not limited in any way, but it is preferable to use a material having a hardness smaller than that of the inner shaft main body 28, and for example, a synthetic resin such as polyamide elastomer, polyester elastomer, or polyurethane is preferable. Can be adopted in.

Further, the method of mounting the covering member 44 on the inner shaft main body 28 is not limited in any way, but for example, a synthetic resin material dissolved in a solvent is applied to the inner shaft main body 28 and dried, or has heat shrinkage. By externally inserting the tubular member into the inner shaft main body 28 and applying heat, the tubular member may be brought into close contact with the inner shaft main body 28. In particular, since the covering member 44 of the present embodiment has a substantially constant outer diameter dimension throughout, the covering member 44 does not require a special operation for changing the outer diameter dimension. Can be easily manufactured.

Further, the radial width dimension α (see FIG. 4) of the covering member 44 is not particularly limited, but for example, the outer diameter dimension φA (see FIG. 4) of the inner shaft main body 28 is 0.5 mm to 0. When the outer diameter dimension φB (see FIG. 4) of the balloon 12 when the diameter is reduced to 6 mm is 2 mm to 3 mm, it is preferably set within the range of 0.1 mm to 0.5 mm. When the outer diameter of the inner shaft body, the balloon at the time of reduction, or both of them is out of the above range, the radial width of the covering member can be appropriately set.

As a method of using the stent delivery catheter 10 of the present embodiment, first, the stent 14 is arranged on the outer peripheral side of the balloon 12 in the wrapped state, and the diameter of the stent 14 is reduced by mechanical treatment or the like to make the stent 14 into the balloon 12. Extrapolate. Then, the catheter 10 is inserted into the lumen and externally inserted into the guide wire inserted into the narrowed portion of the lumen in advance, that is, the guide wire is inserted into the guide wire lumen 32, and the tip portion of the catheter 10 is inserted. To reach the stenosis of the lumen. Then, fluid is supplied into the balloon 12 through the supply / discharge lumen 33 to expand the balloon 12 and the stent 14 extrapolated to the balloon 12. As a result, the stent 14 is pressed against the narrowed portion of the lumen to expand the narrowed portion. Then, the fluid in the balloon 12 is discharged through the supply / discharge lumen 33, the balloon 12 is contracted, and the catheter 10 is withdrawn from the lumen, so that the stent 14 is placed in the narrowed portion of the lumen.

In the stent delivery catheter 10 of the present embodiment having such a structure, since a stent 14 having a relatively large wave number is used as the delivered stent 14, the stent 14 is attached to the balloon 12 by extrapolation when the diameter is reduced. The inner diameter tends to be large. Here, in the catheter 10, since the large diameter portion 42 is provided at the mounting portion of the stent 14 on the inner shaft main body 28, the outer diameter of the balloon 12 in the wrapping state can be increased, and the wrapping state can be increased. It is prevented that the outer diameter of the balloon 12 becomes too small as compared with the inner diameter of the stent 14 when the diameter is reduced. As a result, it is possible to prevent the stent 14 from being unevenly reduced in diameter, and since the stent 14 is extrapolated and mounted on the balloon 12 substantially uniformly, the diameter of the stent 14 is expanded substantially uniformly even when the diameter of the stent 14 is expanded. can do. Further, since it is not necessary to increase the film thickness of the balloon 12 in order to increase the outer diameter dimension of the balloon 12, and the thin-film balloon 12 can be adopted, flexibility at the tip portion of the catheter 10 can be ensured.

In particular, in the present embodiment, since the large diameter portion 42 is formed by mounting the covering member 44 on the outer peripheral surface of the mounting portion of the stent 14 in the inner shaft main body 28, the large diameter portion 42 can be easily provided. Can be formed.

Further, by making the hardness of the covering member 44 smaller than the hardness of the inner shaft main body 28, the flexibility at the tip portion of the catheter 10 can be more reliably ensured.

Further, in the present embodiment, since the guide wire lumen 32 is provided on the inner shaft main body 28, it is not necessary to separately provide the guide wire lumen, and the structure of the catheter 10 can be simplified.

Further, in a preferred embodiment of the present invention, in the stent delivery catheter according to the present invention for coronary arteries, the wave number in one circumference of the stent is 10 to 12. In the present embodiment, the mounted stent 14 has a relatively large wave number per circumference (the number of repeating units of the periodic structure in one circumference) as compared with a general coronary artery stent. Therefore, if it is attempted to reduce the diameter dimension when the diameter of the stent 14 is reduced while ensuring the width dimension of the struts, adjacent struts in the circumferential direction tend to overlap each other, resulting in a distorted diameter reduction shape. Here, in the present invention, by providing the large diameter portion 42 on the mounting portion of the stent 14 on the inner shaft 24, non-uniform diameter reduction deformation due to excessive diameter reduction of the stent 14 can be avoided. By adopting such a stent 14, the ratio of the diameter dimension at the time of expansion to the diameter dimension at the time of contraction of the stent 14 can be set to be large, and the delivery performance into the lumen can be ensured. In addition to being able to handle thick lumens and branched lumens, when used as a drug-eluting stent (DES), the surface area of the stent strut increases, so the amount of drug to be carried should be increased. Is also possible.

Next, FIG. 6 shows a large diameter portion 48 of the inner shaft 46 as a shaft in the stent delivery catheter as the second embodiment of the present invention. In the stent delivery catheter of the present embodiment, the members other than the inner shaft 46 are the same as those of the first embodiment, and thus the illustration is omitted. Further, in the following description, the members or parts substantially the same as those in the first embodiment are designated by the same reference numerals as those in the first embodiment in the drawings, thereby omitting detailed description.

In the first embodiment, the covering member 44 has a tubular shape, and the outer diameter dimension is substantially constant over the entire length in the axial direction. However, in the present embodiment, the inner shaft main body 28 as the shaft main body A large-diameter portion 48 is formed by mounting a covering member 50 spirally extending in the circumferential direction with respect to the outer peripheral surface of the inner shaft main body 28 to the mounting portion of the stent 14 in the above. As a result, the outer diameter dimension of the large diameter portion 48 is made larger than at least the proximal end side adjacent portion 40 thereof. That is, in the present embodiment, the outer diameter dimension of the large diameter portion 48 is partially different in the axial direction.

Even in the stent delivery catheter in which the inner shaft 46 having such a structure is adopted, the same effect as that of the stent delivery catheter 10 described in the first embodiment can be exhibited.

The covering member 50 of the present embodiment has a rectangular cross section. For example, a synthetic resin piece extending linearly is wound around the outer peripheral surface of the inner shaft main body 28 and fixed by adhesion, welding, or the like. A diameter 48 may be configured. However, the covering member is not limited to a rectangular cross section, and various cross-sectional shapes such as a circular cross section, a semicircular cross section, and a polygonal cross section can be adopted. Further, the large-diameter portion is not limited to the mode in which the covering member is spirally provided on the outer peripheral surface of the inner shaft body in the circumferential direction, and a plurality of annular protrusions are provided in the axial direction or the protrusions extending in the axial direction are provided around the circumference. It may be partially provided in the direction. In particular, in a structure in which a plurality of annular ridges are provided in the axial direction, the stent 14 is supported at both ends in the axial direction by providing the ridges at both ends in the axial direction of the mounting portion of the stent 14, and the inner shaft 46 and Stable attachment to the balloon 12 can be achieved.

FIG. 7 shows the distal portion of the stent delivery catheter 60 as a third embodiment of the present invention. The stent delivery catheter 60 of the present embodiment includes an inner shaft 62 as a shaft.

More specifically, the inner shaft 62 has a structure in which the tip tip 30, the covering member 44, and the diameter-expanding member 64 constituting the stent positioning portion are attached to the inner shaft main body 28 as the shaft main body. Has been done.

The diameter-expanding member 64 is an annular or tubular member made of a flexible synthetic resin material similar to the covering member 44, and in the present embodiment, it is located at the distal end and the proximal end of the covering member 44, respectively. It is attached in an extrapolated state and is fixed to the covering member 44 by means such as adhesion or welding. As a result, the large-diameter portion 66 of the present embodiment is formed by the covering member 44 and the diameter-expanding member 64, and the outer diameter dimensions of the large-diameter portion 66 are partially different in the axial direction. At both ends in the axial direction in which the 64 is arranged, stent positioning portions having a diameter larger than that in the intermediate portion in the axial direction away from the diameter-expanding member 64 are provided.

The balloon 12 is fixed to the inner shaft body 28 and the tip 30 distal to the large diameter portion 66, and is fixed to the outer shaft 26 proximal to the large diameter portion 66. The axial intermediate portion is overlapped with the outer peripheral surface of the large diameter portion 66.

Further, the balloon 12 has a large outer diameter dimension in the total length of the portion overlapped with the large diameter portion 66, and at the portion overlapped with both ends in the axial direction of the large diameter portion 66 provided with the diameter expanding member 64. It is said to have a larger diameter. As a result, there is a step between the overlapping portion of the large diameter portion 66 on both ends in the axial direction of the balloon 12 and the overlapping portion of the large diameter portion 66 removed from the diameter expanding member 64 in the axial direction. 68 is formed.

Further, a stent 14 is attached to the balloon 12 in an extrapolated state. That is, the stent 14 is extrapolated to a portion of the balloon 12 that is overlapped with the large diameter portion 66, and is fitted to the outer peripheral surface of the balloon 12 by being deformed in diameter. As described above, also in the present embodiment, the mounting portion of the stent 14 on the inner shaft 62 is a large diameter portion 66 as in the above embodiment.

Further, both ends in the axial direction of the stent 14 are superposed on the diameter-expanding member 64 of the large-diameter portion 66 via the balloon 12, and both ends in the axial direction have a larger diameter than the intermediate portion outside the diameter-expanding member 64. Has been done. As a result, both ends of the stent 14 in the axial direction are fitted to the inner shaft 62 with a larger pressure than the intermediate portion.

Furthermore, there is a step 70 between the attachment portion of the large diameter portion 66 of the stent 14 to both ends in the axial direction and the attachment portion of the large diameter portion 66 detached from the diameter expansion member 64 to the intermediate portion in the axial direction. It is formed. Then, the step 68 of the balloon 12 and the step 70 of the stent 14 are locked in the axial direction, so that the stent 14 is positioned axially with respect to the balloon 12.

According to such a stent delivery catheter 60, the large diameter portion 66 provided on the inner shaft 62 can be appropriately adjusted so that the outer diameter dimension of the balloon 12 in the wrapped state does not become too small. Therefore, for example, even when the balloon 12 is thin and the number of waves of the stent 14 is large, it is possible to prevent the stent 14 externally fitted in the balloon 12 from becoming too small in diameter, and when the diameter of the stent 14 is reduced, the linear body 36 Problems such as overlapping can be avoided.

Further, according to the present embodiment, the outer diameter dimension of both ends in the axial direction of the large diameter portion 66 is made larger by providing the diameter expanding member 64, and the stent position defining portions are located at both ends in the axial direction of the large diameter portion 66. Is provided, and both axially end portions of the stent 14 are attached to the balloon 12 and the inner shaft 62 with greater force. As a result, the stent 14 can be firmly positioned by the balloon 12 and the inner shaft 62 in the contracted state to prevent the stent 14 before expansion from detaching from the inner shaft 62, and at an appropriate position on the balloon 12. Be retained. In particular, since the diameter expanding member 64 is arranged at both ends in the axial direction of the large diameter portion 66, the stent 14 is strongly supported at both ends in the axial direction, and the stent 14 is attached to the balloon 12 and the inner shaft 62. Is maintained more stably.

Moreover, the stent 14 is also axially positioned with respect to the balloon 12 and the inner shaft 62 by engaging the step 68 of the balloon 12 and the step 70 of the stent 14 in the axial direction. As a result, detachment of the stent 14 from the inner shaft 62, displacement of the stent 14 with respect to the balloon 12, and the like are avoided, and the stent 14 before expansion is held in an appropriate mounting state.

The stent positioning portion is not necessarily limited to the one provided at both ends in the axial direction of the large diameter portion 66, and is not necessarily provided at, for example, one end in the axial direction and not at the other end. Alternatively, one or more may be provided in the intermediate portion in the axial direction in addition to or in place of the end portion in the axial direction. Further, the stent positioning portion may be formed by fixing another member such as the diameter expanding member 64 to the inner shaft 62, but for example, the covering member 44 may be partially thickened to form a covering member. It can be provided integrally with the 44, or can be provided by partially increasing the outer diameter dimension of the inner shaft main body 28 in the axial direction.

Further, the step 68 of the balloon 12 and the step 70 of the stent 14 are not essential. For example, the stent 14 may be reduced in diameter to a substantially constant diameter in the total length in the axial direction including the portion where the stent position defining portion (diameter expanding member 64) is removed. In this case, the step 70 of the stent 14 Is not formed. Further, when the entire stent 14 is reduced in diameter to a substantially constant diameter, both ends in the axial direction of the balloon 12 are abutted and supported by the stent positioning portion, while the balloon 12 is removed from the stent positioning portion. In the intermediate portion of the balloon 12, the step 68 of the balloon 12 may not be formed because the state may be separated from the covering member 44 to the outer periphery.

Although the embodiments of the present invention have been described in detail above, the present invention is not limitedly interpreted by the above-mentioned solutions and specific descriptions in the embodiments, and is not deviated from the gist of the present invention. It can be carried out with appropriate modifications and improvements.

For example, in the above-described embodiment, the large-diameter portions 42 and 48 are formed by mounting separate covering members 44 and 50 on the outer peripheral surface of the inner shaft main body 28, but the large-diameter portion is the inner shaft. It may be formed integrally with the main body. That is, when manufacturing the inner shaft main body, the large diameter portion may be formed by manufacturing the outer diameter dimension of the mounting portion of the stent 14 to be larger than that of the proximal end side adjacent portion. At that time, if the stent 14 is manufactured by increasing the inner diameter as well as the outer diameter at the mounting portion, the thickness dimension of the inner shaft body is not increased, so that the flexibility at the catheter tip portion is not impaired. A diameter portion can be formed.

Further, in the above embodiment, the inner shaft main body 28 is tubular and the guide wire lumen 32 is formed by the lumen of the inner shaft main body 28, but the guide wire lumen 32 is not indispensable and the inner shaft. The body may have a solid shaft shape. Further, the distal shaft 20 has a double pipe structure of an inner shaft 24 and an outer shaft 26, but has a double lumen structure having a guide wire lumen and a supply / discharge lumen inside, for example, one shaft. You may. However, since the guide wire lumen is not essential, the distal shaft may have a single-tube structure having only supply and discharge lumens.

Further, in the above embodiment, the guide wire lumen 32 is a rapid exchange type catheter shorter than the total length of the catheter 10, but the guide wire lumen 32 is an over-the-wire type catheter that opens at the proximal end of the connector 18. May be.

Furthermore, the stent adopted in the present invention is not limited to the stent in which one linear body extends spirally in the circumferential direction as described in the above embodiment. That is, one linear body is folded in the axial direction and extends in the circumferential direction to form one annular body, and a plurality of the annular bodies are arranged side by side on the same central axis to form the annular body. It may be a stent that is axially connected at an appropriate position on the circumference.

In the above embodiment, a stent for a coronary artery having a wave number of 10 to 12 has been exemplified, but the stent is not limited in any way. For example, a stent for peripheral blood vessels may be adopted as the stent, and in such a case, the wave number is preferably 18 to 24.

10,60: Stent delivery catheter, 12: Balloon, 14: Stent, 24,46,62: Inner shaft (shaft), 28: Inner shaft body (shaft body), 32: Guide wire lumen, 40: Proximal end side Adjacent part, 42, 48, 66: Large diameter part, 44, 50: Coating member, 64: Diameter expansion member (Stent position defining part)

The present invention relates to a stent delivery catheter for delivering a stent to a stenotic site in a lumen, and more particularly to a stent delivery catheter for delivering a stent having a large number of waves.

Conventionally, when an abnormality such as stenosis or occlusion occurs in a lumen such as a blood vessel, a stent is delivered to a lesion in the lumen by, for example, a stent delivery catheter. Then, by expanding the stent and pressing it against the lumen wall, stent treatment for keeping the lumen in an expanded state is performed. The stent has a small diameter when inserted into the lumen, but is expanded and placed in the lumen. As a method of expanding the diameter of the stent in the lumen, there are expansion by a balloon, in addition to self-expansion and mechanical expansion by a shape memory material or the like.

That is, when the stent is expanded by a balloon, it is extrapolated with the balloon folded with respect to the tip portion of the shaft, as in the stent delivery catheter described in Japanese Patent Application Laid-Open No. 2014-61191 (Patent Document 1). Along with the attachment, a stent is extrapolated and attached to the folded balloon to reduce the diameter. Then, the tip portion of the stent delivery catheter is inserted into the lesion portion in the lumen to expand the balloon, so that the stent extrapolated to the balloon is expanded in diameter and pressed against the lumen wall. The stent is then placed in the lumen by contracting the balloon and removing the catheter.

By the way, as the stent to be placed in the lumen, for example, a stent having a skeleton in which one linear body is continuously extended in a spiral or tubular shape in the circumferential direction while being folded back in the axial direction is adopted. As such a stent, for example, when it is placed in a thick lumen or the like, a stent having a large wave number (number of bent portions) in the circumferential direction and widely expanding when the diameter is expanded is preferably adopted.

On the other hand, the balloon attached to the tip portion of the stent delivery catheter is preferably a balloon having a small film thickness in order to secure the flexibility of the tip portion of the catheter.

However, since the outer diameter of a balloon having a small film thickness becomes small when folded, there is a risk that the stent may not be uniformly reduced in diameter when a stent having a large wave number is extrapolated and subjected to diameter reduction treatment. Specifically, there was a risk that adjacent struts in the circumferential direction of the stent would partially overlap. In addition, this may cause a problem that the stent does not expand uniformly when the balloon is expanded to expand the diameter of the stent.

Japanese Unexamined Patent Publication No. 2014-61191

The present invention has been made in the background of the above circumstances, and the problem to be solved is to uniformly reduce the diameter of the stent even when the stent is attached to the balloon, particularly when the stent having a large wave number is attached. It is an object of the present invention to provide a stent delivery catheter having a novel structure that can be attached to the stent.

Hereinafter, aspects of the present invention made to solve such problems will be described. The components adopted in each of the following aspects can be adopted in any combination as much as possible.

That is, the present invention
(1) A balloon is attached to the tip of the shaft, and a stent is attached to the folded balloon. The stent has a turn portion curved in a substantially arc shape and is folded back in the axial direction in the circumferential direction. In a stent delivery catheter for a coronary artery having a skeletal structure extending to, a covering member is attached to the outer peripheral surface of the shaft body at the balloon and the mounting portion of the stent on the shaft, and the covering member is attached. A large diameter portion having an increased outer diameter dimension of the shaft is provided over the entire length of the stent, and the outer diameter dimension of the large diameter portion is made constant over the entire length of the stent. While the hardness of the member is smaller than the hardness of the shaft body, the turn portion is folded back more than 180 degrees in the reduced diameter state of the stent mounted on the balloon, and the stent is folded back more than 180 degrees. , Stent delivery catheter, characterized in that the folded parts do not overlap each other,
(2) The tip portion of the balloon extends toward the tip side of the covering member, and the inner diameter of the extending tip portion is reduced to the outside of the shaft protruding toward the tip side of the covering member. The stent delivery catheter according to (1), which is inserted and fixed, and the outer diameter of the extended tip portion is gradually reduced toward the tip side.
(3) The stent delivery catheter according to (1) or (2), wherein the number of the turn portions in the circumferential direction is 10 to 12.
(4) Any one of (1) to (3), wherein the outer diameter dimension of the shaft body is 0.5 to 0.6 mm, and the radial width dimension of the covering member is 0.1 to 0.5 mm. Stent delivery catheters, as described in
(5) The stent delivery catheter according to any one of (1) to (4), wherein the shaft is provided with a guide wire lumen through which a guide wire is inserted.

According to the stent delivery catheter having a structure according to the present invention, since a large diameter portion is provided in the stent mounting portion on the shaft, the outer diameter of the balloon at the time of folding can be greatly adjusted and set. As a result, uneven diameter reduction of the stent mounted on the balloon can be avoided, and the stent can be stably mounted.

The front view which shows the whole of the stent delivery catheter as the 1st Embodiment of this invention. The front view which shows the main part of the stent delivery catheter shown in FIG. 1 in an enlarged manner. FIG. 2 is a vertical cross-sectional view of a main part of the stent delivery catheter shown in FIG. An enlarged view of the IV-IV cross section of FIG. It is a figure which shows a specific example of the stent which can be adopted in this invention, and is the development view which opened at one place in the circumferential direction. The vertical sectional view which shows the large diameter part of the shaft in the stent delivery catheter as the 2nd Embodiment of this invention. The vertical sectional view of the main part in the stent delivery catheter as the 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, FIGS. 1 to 4 show a stent delivery catheter (hereinafter, catheter) 10 as a first embodiment of the present invention. A balloon 12 is attached to the tip of the catheter 10, and a stent 14 is extrapolated to the balloon 12. Then, the stent 14 is delivered and placed in the narrowed portion of the lumen such as a blood vessel by the catheter 10, so that the narrowed portion of the lumen is maintained in an expanded state. In the following description, the proximal end side refers to the right side in FIG. 1 where the user operates the catheter 10, and the distal end side is a diagram which is far from the user during use. Say the left side of 1. Further, the axial direction refers to the left-right direction in FIG. 1, which is the length direction of the catheter 10.

More specifically, the catheter 10 of the present embodiment has a structure in which the connector 18 is provided on the proximal end side of the catheter body 16. The catheter body 16 is configured by connecting the distal shaft 20 on the distal end side and the proximal shaft 22 on the proximal end side in the axial direction.

The proximal shaft 22 has a single-tube structure extending in the axial direction, and is formed of, for example, a synthetic resin such as a polyamide elastomer or a metal such as stainless steel. The proximal end of the proximity shaft 22 is connected to the connector 18, and the lumen of the proximity shaft 22 is communicated to the external space through the connector 18.

On the other hand, the distal shaft 20 has a double pipe structure of an inner shaft 24 and an outer shaft 26 as a shaft as a whole. The inner shaft 24 includes an inner shaft main body 28, and the outer diameter dimension of the inner shaft main body 28 is smaller than the inner diameter dimension of the outer shaft 26. Further, the proximal end of the inner shaft body 28 is inserted into the outer shaft 26, and the distal end of the inner shaft body 28 protrudes from the distal end of the outer shaft 26.

Here, the outer shaft 26 has a tubular shape extending in the axial direction, and is formed of a synthetic resin such as a polyamide elastomer. The outer diameter of the outer shaft 26 is substantially equal to that of the proximity shaft 22, and the proximal end of the outer shaft 26 and the distal end of the proximity shaft 22 are connected. As a result, the lumen of the outer shaft 26 and the lumen of the proximal shaft 22 are communicated with each other.

Further, the inner shaft main body 28 has a tubular shape extending in the axial direction as a whole, and is formed of a synthetic resin such as a polyamide elastomer. A tip tip 30 is fixed to the distal end of the inner shaft body 28. The tip 30 has a cylindrical shape and has substantially the same outer diameter as the inner shaft body 28. On the other hand, the proximal end of the inner shaft body 28 is bent and opens on the outer peripheral surface of the outer shaft 26. As a result, the lumen of the inner shaft body 28 is a lumen that opens at the tip of the catheter 10 and the intermediate portion in the axial direction, and this lumen is a guide wire lumen through which a guide wire for guiding the catheter 10 is inserted. It is 32. That is, the catheter 10 of the present embodiment is a rapid exchange type catheter in which the guide wire lumen is shorter than the total length in the axial direction of the catheter.

A balloon 12 is attached to the tip of the inner shaft 24 having such a structure. The balloon 12 can be expanded and contracted by introducing and discharging a fluid inside, and is a tubular or bag-shaped member formed of a thin-film synthetic resin, a rubber film, or the like. The material of the balloon 12 is not limited in any way, but in the present embodiment, the balloon 12 is made of nylon resin, and the balloon 12 is subjected to the pressure applied when the fluid is supplied to the inside and expanded. It is said to be a low compliant balloon with a small change in outer diameter. Further, in order to suppress the influence on the flexibility of the inner shaft 24, it is desirable that the balloon 12 is made as thin as possible while ensuring the strength capable of expanding the diameter of the stent 14 described later at the time of expansion.

The distal end of the balloon 12 is fixed to the distal end of the inner shaft body 28 and the outer peripheral surface of the tip tip 30 by adhesion or the like, while the proximal end of the balloon 12 is the outer periphery of the distal end of the outer shaft 26. It is fixed to the surface by adhesion or the like. Therefore, the space between the inner shaft main body 28 and the outer shaft 26 in the radial direction is communicated with the internal space of the balloon 12, while being communicated with the external space through the proximal shaft 22. As a result, fluid can be introduced and discharged from the external space into the internal space of the balloon 12 through the space between the inner shaft body 28 and the outer shaft 26 in the radial direction, and from the internal space of the balloon 12 to the external space. The entire cavity is a supply / discharge lumen 33 that supplies / discharges fluid to / from the balloon 12.

Further, substantially cylindrical markers 34 and 34 are extrapolated on the outer peripheral surfaces of the inner shaft main body 28 at both ends in the axial direction of the balloon 12. These markers 34, 34 are made of a material such as platinum, which is opaque to X-rays.

As shown in FIG. 4, the balloon 12 in the initial state is in a wrapping state in which the balloon 12 is folded in the circumferential direction so as to overlap in the radial direction.

A substantially tubular stent 14 extending in the axial direction as a whole is extrapolated and attached to the balloon 12. The shape of the stent is not limited as long as it has a skeletal structure that extends in the circumferential direction while being folded back in the axial direction, but the stent 14 of the present embodiment is shown in FIG. 5 as a specific example. As shown, one linear body 36 has a skeletal structure that reciprocates in the axial direction with a substantially constant amplitude and extends spirally in the circumferential direction as a whole. In particular, it is preferable that the number of waves in the circumferential direction in one round, that is, the number of repeating units of the periodic structure in one round of the linear body 36 is 10 to 12, which is larger than that of a general coronary stent. In the form of the stent 14, it is 12 waves. The material of the stent is not limited in any way, but the stent 14 of the present embodiment is formed of a cobalt-chromium alloy. As shown in FIG. 2, in the stent 14, one linear body 36 constitutes a plurality of annular bodies 38, and the plurality of annular bodies 38 are arranged in parallel in the axial direction. It has a structure, and the annular bodies 38, 38 adjacent to each other in the axial direction may be connected and reinforced at appropriate points in the circumferential direction.

By adopting a stent having a larger wave number than a general stent as described above, the diameter of the stent can be further expanded at the time of diameter expansion, and it becomes possible to handle, for example, a thicker lumen or a branched lumen. .. Further, since the wave number is large, the surface area of the linear body 36 can be increased, and when it is used as a drug-eluting stent (DES), the amount of the drug applied to the surface of the linear body 36 is increased. Can be made to.

In the initial state, the stent 14 is extrapolated and attached to the balloon 12 as shown in FIG. 2 and the like by mechanically reducing the diameter.

Here, the mounting portion of the stent 14 on the inner shaft 24 is provided with a large diameter portion 42 having an outer diameter larger than that of the proximal end side adjacent portion 40 of the mounting portion. In the present embodiment, in the mounting portion of the stent 14, the covering member 44 is mounted on the outer peripheral surface of the inner shaft main body 28, so that the outer diameter dimension is larger than that of the proximal end side adjacent portion 40 of the mounting portion of the stent 14. A large diameter portion 42 having a large diameter is configured. Further, in the present embodiment, the inner shaft 24 is composed of the inner shaft main body 28 and the covering member 44.

The covering member 44 has a substantially tubular shape extending in the axial direction, and in the present embodiment, the covering member 44 has an axial dimension substantially the same as or slightly larger than the axial dimension of the stent 14, and the total length in the axial direction. It has a substantially constant outer diameter dimension. That is, in the present embodiment, the outer diameter dimension of the large diameter portion 42 is substantially constant throughout. Then, on the outer peripheral side of the covering member 44, the stent 14 is mounted on the balloon 12. The material of the covering member 44 is not limited in any way, but it is preferable to use a material having a hardness smaller than that of the inner shaft main body 28, and for example, a synthetic resin such as polyamide elastomer, polyester elastomer, or polyurethane is preferable. Can be adopted in.

Further, the method of mounting the covering member 44 on the inner shaft main body 28 is not limited in any way, but for example, a synthetic resin material dissolved in a solvent is applied to the inner shaft main body 28 and dried, or has heat shrinkage. By externally inserting the tubular member into the inner shaft main body 28 and applying heat, the tubular member may be brought into close contact with the inner shaft main body 28. In particular, since the covering member 44 of the present embodiment has a substantially constant outer diameter dimension throughout, the covering member 44 does not require a special operation for changing the outer diameter dimension. Can be easily manufactured.

Further, the radial width dimension α (see FIG. 4) of the covering member 44 is not particularly limited, but for example, the outer diameter dimension φA (see FIG. 4) of the inner shaft main body 28 is 0.5 mm to 0. When the outer diameter dimension φB (see FIG. 4) of the balloon 12 when the diameter is reduced to 6 mm is 2 mm to 3 mm, it is preferably set within the range of 0.1 mm to 0.5 mm. When the outer diameter of the inner shaft body, the balloon at the time of reduction, or both of them is out of the above range, the radial width of the covering member can be appropriately set.

As a method of using the stent delivery catheter 10 of the present embodiment, first, the stent 14 is arranged on the outer peripheral side of the balloon 12 in the wrapped state, and the diameter of the stent 14 is reduced by mechanical treatment or the like to make the stent 14 into the balloon 12. Extrapolate. Then, the catheter 10 is inserted into the lumen and externally inserted into the guide wire inserted into the narrowed portion of the lumen in advance, that is, the guide wire is inserted into the guide wire lumen 32, and the tip portion of the catheter 10 is inserted. To reach the stenosis of the lumen. Then, fluid is supplied into the balloon 12 through the supply / discharge lumen 33 to expand the balloon 12 and the stent 14 extrapolated to the balloon 12. As a result, the stent 14 is pressed against the narrowed portion of the lumen to expand the narrowed portion. Then, the fluid in the balloon 12 is discharged through the supply / discharge lumen 33, the balloon 12 is contracted, and the catheter 10 is withdrawn from the lumen, so that the stent 14 is placed in the narrowed portion of the lumen.

In the stent delivery catheter 10 of the present embodiment having such a structure, since a stent 14 having a relatively large wave number is used as the delivered stent 14, the stent 14 is attached to the balloon 12 by extrapolation when the diameter is reduced. The inner diameter tends to be large. Here, in the catheter 10, since the large diameter portion 42 is provided at the mounting portion of the stent 14 on the inner shaft main body 28, the outer diameter of the balloon 12 in the wrapping state can be increased, and the wrapping state can be increased. It is prevented that the outer diameter of the balloon 12 becomes too small as compared with the inner diameter of the stent 14 when the diameter is reduced. As a result, it is possible to prevent the stent 14 from being unevenly reduced in diameter, and since the stent 14 is extrapolated and mounted on the balloon 12 substantially uniformly, the diameter of the stent 14 is expanded substantially uniformly even when the diameter of the stent 14 is expanded. can do. Further, since it is not necessary to increase the film thickness of the balloon 12 in order to increase the outer diameter dimension of the balloon 12, and the thin-film balloon 12 can be adopted, flexibility at the tip portion of the catheter 10 can be ensured.

In particular, in the present embodiment, since the large diameter portion 42 is formed by mounting the covering member 44 on the outer peripheral surface of the mounting portion of the stent 14 in the inner shaft main body 28, the large diameter portion 42 can be easily provided. Can be formed.

Further, by making the hardness of the covering member 44 smaller than the hardness of the inner shaft main body 28, the flexibility at the tip portion of the catheter 10 can be more reliably ensured.

Further, in the present embodiment, since the guide wire lumen 32 is provided on the inner shaft main body 28, it is not necessary to separately provide the guide wire lumen, and the structure of the catheter 10 can be simplified.

Further, in a preferred embodiment of the present invention, in the stent delivery catheter according to the present invention for coronary arteries, the wave number in one circumference of the stent is 10 to 12. In the present embodiment, the mounted stent 14 has a relatively large wave number per circumference (the number of repeating units of the periodic structure in one circumference) as compared with a general coronary artery stent. Therefore, if it is attempted to reduce the diameter dimension when the diameter of the stent 14 is reduced while ensuring the width dimension of the struts, adjacent struts in the circumferential direction tend to overlap each other, resulting in a distorted diameter reduction shape. Here, in the present invention, by providing the large diameter portion 42 on the mounting portion of the stent 14 on the inner shaft 24, non-uniform diameter reduction deformation due to excessive diameter reduction of the stent 14 can be avoided. By adopting such a stent 14, the ratio of the diameter dimension at the time of expansion to the diameter dimension at the time of contraction of the stent 14 can be set to be large, and the delivery performance into the lumen can be ensured. In addition to being able to handle thick lumens and branched lumens, when used as a drug-eluting stent (DES), the surface area of the stent strut increases, so the amount of drug to be carried should be increased. Is also possible.

Next, FIG. 6 shows a large diameter portion 48 of the inner shaft 46 as a shaft in the stent delivery catheter as the second embodiment of the present invention. In the stent delivery catheter of the present embodiment, the members other than the inner shaft 46 are the same as those of the first embodiment, and thus the illustration is omitted. Further, in the following description, the members or parts substantially the same as those in the first embodiment are designated by the same reference numerals as those in the first embodiment in the drawings, thereby omitting detailed description.

In the first embodiment, the covering member 44 has a tubular shape, and the outer diameter dimension is substantially constant over the entire length in the axial direction. However, in the present embodiment, the inner shaft main body 28 as the shaft main body A large-diameter portion 48 is formed by mounting a covering member 50 spirally extending in the circumferential direction with respect to the outer peripheral surface of the inner shaft main body 28 to the mounting portion of the stent 14 in the above. As a result, the outer diameter dimension of the large diameter portion 48 is made larger than at least the proximal end side adjacent portion 40 thereof. That is, in the present embodiment, the outer diameter dimension of the large diameter portion 48 is partially different in the axial direction.

Even in the stent delivery catheter in which the inner shaft 46 having such a structure is adopted, the same effect as that of the stent delivery catheter 10 described in the first embodiment can be exhibited.

The covering member 50 of the present embodiment has a rectangular cross section. For example, a synthetic resin piece extending linearly is wound around the outer peripheral surface of the inner shaft main body 28 and fixed by adhesion, welding, or the like. A diameter 48 may be configured. However, the covering member is not limited to a rectangular cross section, and various cross-sectional shapes such as a circular cross section, a semicircular cross section, and a polygonal cross section can be adopted. Further, the large-diameter portion is not limited to the mode in which the covering member is spirally provided on the outer peripheral surface of the inner shaft body in the circumferential direction, and a plurality of annular protrusions are provided in the axial direction or the protrusions extending in the axial direction are provided around the circumference. It may be partially provided in the direction. In particular, in a structure in which a plurality of annular ridges are provided in the axial direction, the stent 14 is supported at both ends in the axial direction by providing the ridges at both ends in the axial direction of the mounting portion of the stent 14, and the inner shaft 46 and Stable attachment to the balloon 12 can be achieved.

FIG. 7 shows the distal portion of the stent delivery catheter 60 as a third embodiment of the present invention. The stent delivery catheter 60 of the present embodiment includes an inner shaft 62 as a shaft.

More specifically, the inner shaft 62 has a structure in which the tip tip 30, the covering member 44, and the diameter-expanding member 64 constituting the stent positioning portion are attached to the inner shaft main body 28 as the shaft main body. Has been done.

The diameter-expanding member 64 is an annular or tubular member made of a flexible synthetic resin material similar to the covering member 44, and in the present embodiment, it is located at the distal end and the proximal end of the covering member 44, respectively. It is attached in an extrapolated state and is fixed to the covering member 44 by means such as adhesion or welding. As a result, the large-diameter portion 66 of the present embodiment is formed by the covering member 44 and the diameter-expanding member 64, and the outer diameter dimensions of the large-diameter portion 66 are partially different in the axial direction. At both ends in the axial direction in which the 64 is arranged, stent positioning portions having a diameter larger than that in the intermediate portion in the axial direction away from the diameter-expanding member 64 are provided.

The balloon 12 is fixed to the inner shaft body 28 and the tip 30 distal to the large diameter portion 66, and is fixed to the outer shaft 26 proximal to the large diameter portion 66. The axial intermediate portion is overlapped with the outer peripheral surface of the large diameter portion 66.

Further, the balloon 12 has a large outer diameter dimension in the total length of the portion overlapped with the large diameter portion 66, and at the portion overlapped with both ends in the axial direction of the large diameter portion 66 provided with the diameter expanding member 64. It is said to have a larger diameter. As a result, there is a step between the overlapping portion of the large diameter portion 66 on both ends in the axial direction of the balloon 12 and the overlapping portion of the large diameter portion 66 removed from the diameter expanding member 64 in the axial direction. 68 is formed.

Further, a stent 14 is attached to the balloon 12 in an extrapolated state. That is, the stent 14 is extrapolated to a portion of the balloon 12 that is overlapped with the large diameter portion 66, and is fitted to the outer peripheral surface of the balloon 12 by being deformed in diameter. As described above, also in the present embodiment, the mounting portion of the stent 14 on the inner shaft 62 is a large diameter portion 66 as in the above embodiment.

Further, both ends in the axial direction of the stent 14 are superposed on the diameter-expanding member 64 of the large-diameter portion 66 via the balloon 12, and both ends in the axial direction have a larger diameter than the intermediate portion outside the diameter-expanding member 64. Has been done. As a result, both ends of the stent 14 in the axial direction are fitted to the inner shaft 62 with a larger pressure than the intermediate portion.

Furthermore, there is a step 70 between the attachment portion of the large diameter portion 66 of the stent 14 to both ends in the axial direction and the attachment portion of the large diameter portion 66 detached from the diameter expansion member 64 to the intermediate portion in the axial direction. It is formed. Then, the step 68 of the balloon 12 and the step 70 of the stent 14 are locked in the axial direction, so that the stent 14 is positioned axially with respect to the balloon 12.

According to such a stent delivery catheter 60, the large diameter portion 66 provided on the inner shaft 62 can be appropriately adjusted so that the outer diameter dimension of the balloon 12 in the wrapped state does not become too small. Therefore, for example, even when the balloon 12 is thin and the number of waves of the stent 14 is large, it is possible to prevent the stent 14 externally fitted in the balloon 12 from becoming too small in diameter, and when the diameter of the stent 14 is reduced, the linear body 36 Problems such as overlapping can be avoided.

Further, according to the present embodiment, the outer diameter dimension of both ends in the axial direction of the large diameter portion 66 is made larger by providing the diameter expanding member 64, and the stent position defining portions are located at both ends in the axial direction of the large diameter portion 66. Is provided, and both axially end portions of the stent 14 are attached to the balloon 12 and the inner shaft 62 with greater force. As a result, the stent 14 can be firmly positioned by the balloon 12 and the inner shaft 62 in the contracted state to prevent the stent 14 before expansion from detaching from the inner shaft 62, and at an appropriate position on the balloon 12. Be retained. In particular, since the diameter expanding member 64 is arranged at both ends in the axial direction of the large diameter portion 66, the stent 14 is strongly supported at both ends in the axial direction, and the stent 14 is attached to the balloon 12 and the inner shaft 62. Is maintained more stably.

Moreover, the stent 14 is also axially positioned with respect to the balloon 12 and the inner shaft 62 by engaging the step 68 of the balloon 12 and the step 70 of the stent 14 in the axial direction. As a result, detachment of the stent 14 from the inner shaft 62, displacement of the stent 14 with respect to the balloon 12, and the like are avoided, and the stent 14 before expansion is held in an appropriate mounting state.

The stent positioning portion is not necessarily limited to the one provided at both ends in the axial direction of the large diameter portion 66, and is not necessarily provided at, for example, one end in the axial direction and not at the other end. Alternatively, one or more may be provided in the intermediate portion in the axial direction in addition to or in place of the end portion in the axial direction. Further, the stent positioning portion may be formed by fixing another member such as the diameter expanding member 64 to the inner shaft 62, but for example, the covering member 44 may be partially thickened to form a covering member. It can be provided integrally with the 44, or can be provided by partially increasing the outer diameter dimension of the inner shaft main body 28 in the axial direction.

Further, the step 68 of the balloon 12 and the step 70 of the stent 14 are not essential. For example, the stent 14 may be reduced in diameter to a substantially constant diameter in the total length in the axial direction including the portion where the stent position defining portion (diameter expanding member 64) is removed. In this case, the step 70 of the stent 14 Is not formed. Further, when the entire stent 14 is reduced in diameter to a substantially constant diameter, both ends in the axial direction of the balloon 12 are abutted and supported by the stent positioning portion, while the balloon 12 is removed from the stent positioning portion. In the intermediate portion of the balloon 12, the step 68 of the balloon 12 may not be formed because the state may be separated from the covering member 44 to the outer periphery.

Although the embodiments of the present invention have been described in detail above, the present invention is not limitedly interpreted by the above-mentioned solutions and specific descriptions in the embodiments, and is not deviated from the gist of the present invention. It can be carried out with appropriate modifications and improvements.

For example, in the above-described embodiment, the large-diameter portions 42 and 48 are formed by mounting separate covering members 44 and 50 on the outer peripheral surface of the inner shaft main body 28, but the large-diameter portion is the inner shaft. It may be formed integrally with the main body. That is, when manufacturing the inner shaft main body, the large diameter portion may be formed by manufacturing the outer diameter dimension of the mounting portion of the stent 14 to be larger than that of the proximal end side adjacent portion. At that time, if the stent 14 is manufactured by increasing the inner diameter as well as the outer diameter at the mounting portion, the thickness dimension of the inner shaft body is not increased, so that the flexibility at the catheter tip portion is not impaired. A diameter portion can be formed.

Further, in the above embodiment, the inner shaft main body 28 is tubular and the guide wire lumen 32 is formed by the lumen of the inner shaft main body 28, but the guide wire lumen 32 is not indispensable and the inner shaft. The body may have a solid shaft shape. Further, the distal shaft 20 has a double pipe structure of an inner shaft 24 and an outer shaft 26, but has a double lumen structure having a guide wire lumen and a supply / discharge lumen inside, for example, one shaft. You may. However, since the guide wire lumen is not essential, the distal shaft may have a single-tube structure having only supply and discharge lumens.

Further, in the above embodiment, the guide wire lumen 32 is a rapid exchange type catheter shorter than the total length of the catheter 10, but the guide wire lumen 32 is an over-the-wire type catheter that opens at the proximal end of the connector 18. May be.

Furthermore, the stent adopted in the present invention is not limited to the stent in which one linear body extends spirally in the circumferential direction as described in the above embodiment. That is, one linear body is folded in the axial direction and extends in the circumferential direction to form one annular body, and a plurality of the annular bodies are arranged side by side on the same central axis to form the annular body. It may be a stent that is axially connected at an appropriate position on the circumference.

In the above embodiment, a stent for a coronary artery having a wave number of 10 to 12 has been exemplified, but the stent is not limited in any way. For example, a stent for peripheral blood vessels may be adopted as the stent, and in such a case, the wave number is preferably 18 to 24.

The present invention originally includes the inventions described below, and the configuration and action / effect thereof will be added.
(I) A skeletal structure in which a balloon is attached to the tip of the shaft and a stent is attached to the balloon, and the stent has a turn portion curved in a substantially arc shape and is bent in the axial direction while extending in the circumferential direction. In the stent delivery catheter possessed, the mounting portion of the stent on the shaft has a larger outer diameter than the proximal end side adjacent portion of the mounting portion, and the stent is adjacent to the stent in the circumferential direction. A stent delivery catheter characterized in that a large-diameter portion is provided so that the catheters do not overlap each other and are folded back more than 180 degrees at the folded turn portion.
(Ii) The outer diameter dimension of the large diameter portion is larger than the outer diameter dimension of the proximal end side adjacent portion of the mounting portion in the shaft body due to the mounting member mounted on the outer peripheral surface of the shaft body. The stent delivery catheter according to (i).
(Iii) The stent delivery catheter according to (ii), wherein the hardness of the covering member is smaller than the hardness of the shaft body.
(Iv) The stent delivery catheter according to any one of (i) to (iii), wherein the outer diameter dimension of the large diameter portion is constant over the entire area.
(V) The stent delivery catheter according to any one of (i) to (iii), wherein the outer diameter dimension of the large diameter portion is partially different.
(Vi) The large-diameter portion is partially provided with a stent positioning portion having a larger outer diameter than the other axial portion in the large-diameter portion in the axial direction (v). Stent delivery catheter,
(Vi) The stent delivery catheter according to any one of (i) to (vi), wherein the shaft is provided with a guide wire lumen through which a guide wire is inserted.
(Viii) It has a skeletal structure that extends in the circumferential direction while folding back in the axial direction with a turn portion curved in a substantially arc shape, and in the mounted state extrapolated to the shaft, adjacent parts in the circumferential direction do not overlap each other. And a stent that is folded back more than 180 degrees at the folded turn part,
Including inventions related to.
In the invention described in (i) above, since the large diameter portion is provided in the portion where the stent is mounted on the shaft, the outer diameter of the balloon at the time of folding can be set to the large diameter portion regardless of the thickness of the balloon. It becomes possible to set appropriately depending on the outer diameter dimension. As a result, for example, even if a balloon having a thin film thickness and a stent having a large wave number are used at the same time, it is possible to prevent the outer diameter of the balloon when folded from becoming too small as compared with the inner diameter of the stent when the diameter is reduced. Therefore, even when the stent is reduced in diameter and mounted on the balloon, uneven diameter reduction such as excessive diameter reduction of the stent and overlapping struts can be effectively avoided.
In the invention described in (ii) above, the outer diameter dimension of the large-diameter portion is such that by mounting the covering member on the outer peripheral surface of the shaft body, the proximal end side adjacent portion of the stent mounting portion in the shaft body Since it is larger than the outer diameter dimension, the large diameter portion can be formed with a simple structure.
In the invention described in (iii) above, since the hardness of the covering member is smaller than the hardness of the shaft body, flexibility at the tip portion of the stent delivery catheter can be sufficiently ensured. The material of the covering member is not limited in any way, but synthetic resins such as polyamide elastomer, polyester elastomer, and polyurethane can be preferably used.
In the invention described in (iv) above, since the outer diameter dimension of the large diameter portion is constant over the entire area, the support surface of the folded balloon is set as the circumferential surface, and the area of the support surface is increased. It can be secured more stably. In the large-diameter portion of this embodiment, for example, when the shaft is manufactured, the stent mounting portion is uniformly thickened, a synthetic resin material is applied to the tip portion of the shaft, or a tubular member is used for the shaft. It can be formed by a simple means such as extrapolation and mounting on the.
In the invention described in (v) above, the outer diameter dimension of the large diameter portion is partially different, and the degree of freedom in the structure and manufacture of the large diameter portion can be expanded. Specifically, for example, the large-diameter portion may have a shape that extends spirally in the circumferential direction with respect to the shaft, or a plurality of ridges are provided at a predetermined distance in the axial direction or the circumferential direction. Such a shape or a structure in which a mesh-like convex portion is provided on the outer peripheral surface of the shaft may be used.
In the invention described in the above (vi), since the stent positioning portion having a larger outer diameter dimension is partially provided in the axial direction on the large diameter portion of the shaft, the stent is further formed in the stent positioning portion. It is positioned and mounted on the shaft with a strong holding force to prevent the stent from falling off the shaft. Moreover, by making the shaft side a large diameter, it is not necessary to significantly reduce the diameter of the stent in order to obtain a strong holding force, and the overlapping of struts is avoided when the diameter is reduced, and the diameter of the stent can be expanded stably. Will be done. Further, when the diameter of the stent extrapolated to the shaft and the balloon is reduced, the inner diameter of the stent may be smaller than the outer diameter of the stent positioning portion in the region where the stent deviates from the stent positioning portion of the large diameter portion. According to this, since the stent is axially locked to the stent positioning portion and the stent is positioned axially with respect to the shaft, it is possible to further prevent the stent from falling off from the shaft. ..
In the invention described in (vii) above, the catheter can be easily guided along the guide wire to the lesion. In particular, since the shaft is provided with guide wire lumens, structural complications can be avoided. The stent delivery catheter according to the present invention may be a rapid exchange type catheter or an over-the-wire type catheter.

10,60: Stent delivery catheter, 12: Balloon, 14: Stent, 24,46,62: Inner shaft (shaft), 28: Inner shaft body (shaft body), 32: Guide wire lumen, 40: Proximal end side Adjacent part, 42,48,66: Large diameter part, 44,50: Coating member, 64: Diameter expansion member (Stent position defining part)

Claims (8)

A balloon is attached to the tip of the shaft, and a stent is attached to the balloon, and the stent has a skeletal structure that extends in the circumferential direction while folding back in the axial direction with a turn portion curved in a substantially arc shape. In the stent delivery catheter
The mounting portion of the stent on the shaft has a larger outer diameter than the proximal end side adjacent portion of the mounting portion, so that the portions adjacent to the stent in the circumferential direction do not overlap each other and the turn is folded back. A stent delivery catheter characterized in that a large-diameter portion is provided so that the portion is folded back more than 180 degrees. The outer diameter dimension of the large diameter portion is made larger than the outer diameter dimension of the proximal end side adjacent portion of the mounting portion in the shaft body by mounting the covering member on the outer peripheral surface of the shaft body. The stent delivery catheter according to claim 1. The stent delivery catheter according to claim 2, wherein the hardness of the covering member is smaller than the hardness of the shaft body. The stent delivery catheter according to any one of claims 1 to 3, wherein the outer diameter dimension of the large diameter portion is constant throughout. The stent delivery catheter according to any one of claims 1 to 3, wherein the outer diameter dimension of the large diameter portion is partially different. The stent delivery according to claim 5, wherein the large-diameter portion is partially provided with a stent positioning portion having a larger outer diameter than the other axial portion in the large-diameter portion in the axial direction. catheter. The stent delivery catheter according to any one of claims 1 to 6, wherein the shaft is provided with a guide wire lumen through which a guide wire is inserted. It has a skeletal structure that extends in the circumferential direction while folding back in the axial direction with a turn portion curved in a substantially arc shape, and in the mounted state extrapolated to the shaft, the adjacent parts in the circumferential direction do not overlap each other and are folded back. A stent characterized by being folded back more than 180 degrees at the turn.

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