JP2006136589A - Flexible stent with superior blood vessel follow-up property and expandability - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible stent having a superior follow-up property of a lumen, and the like (consequently, capable of passing the lumen meandering three-dimensionally), substantially causing no shortening, and capable of forming a lateral hole in the stent. <P>SOLUTION: This stent is a tubular member formed by having a plurality of annular members 1 aligned longitudinally for retaining a biolumen in an opened state, and a single or a plurality of connecting elements 2 connecting the longitudinally adjoining annular members 1 and 1 to each other. The annular member 1 is constituted of a plurality of first annular member elements 11 and second annular member elements 12 continued in the circumferential direction and can be radially expanded. The phases of the adjoining annular members 1 and 1 are deflected by 1/2 wavelength from each other, and a part connecting the curve element 115 of the first annular member element to a low-order linear element 113 and a part connecting the curve element 125 of the second annular member element 12 to a low-order linear element 123 are connected on a longitudinal same line by three connecting elements 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a so-called stent that is implanted in a living body for the purpose of maintaining the lumen diameter of a body lumen such as a blood vessel.

Conventionally, a stent has been employed to expand the diameter of a lumen of a blood vessel or the like and maintain the size of the obtained lumen. Examples of stent expansion methods include balloon expansion, self-expansion using a shape memory material, and mechanical expansion, but balloon expansion is common. In the case of balloon expansion, the stent is introduced together with the balloon catheter to the desired location on the body and expanded by balloon inflation to expand the lumen diameter. The stent is usually composed of a lumen diameter holding portion for expanding and holding a lumen diameter of a blood vessel and the like, and a joint portion connecting them in the longitudinal direction, and the expanded shape is maintained.
As a stent composed of such a lumen diameter holding portion and a joint portion, a plurality of cylindrical elements that can be expanded independently in the radial direction are connected so as to be substantially aligned with a common axis (Patent Document 1) , Comprising a radially extensible tubular member formed by a plurality of elongated members intersecting each other (Patent Document 2), a plurality of substantially straight and overlapping members connected together at an axial bending portion Comprising at least two single wire-like circular members bent so as to form non-segments, wherein the circular members are firmly connected to each other by an axial bending portion (Patent Document 3), first and second A tube having a pattern shape having first and second meander patterns having axes extending in the direction (Patent Document 4), a plurality of cylindrical segments are gathered together by diagonally interconnecting elements, and the ends are connected. Those of the open structure type (Patent Document 5) have been proposed consisting of struts.

However, although these conventional stents have been improved, the stent still imposes a load on the lumen of the blood vessel or the like in the vicinity of the stent edge when expanded, so that the occlusion or stenosis of the lumen or the like does not occur. It sometimes occurred. Moreover, since it cannot be said that it has sufficient flexibility, when the lumen etc. meandered three-dimensionally, it was sometimes difficult to carry the stent to the target site. In addition, blood vessels may be damaged when the stent is carried to the target site. In addition, when there is a branched blood vessel at the indwelling position, it is often difficult to form a lateral hole in the indwelling stent.

JP-A-6-181993 Japanese Patent Laid-Open No. 62-231657 JP-A-8-1555035 Japanese National Patent Publication No. 10-503676 Japanese National Patent Publication No. 11-505441

  The present invention has been made in view of the above circumstances, and is excellent in followability to a lumen or the like (and thus can pass through a three-dimensionally meandering lumen), and is substantially free from shortening. It is possible to provide a flexible stent having excellent expandability.

  The present invention includes a plurality of radially expandable annular members arranged in the longitudinal direction and one or more curved connection elements that connect the adjacent annular members in the longitudinal direction. In the annular member, the first annular member element and the second annular member element are alternately continuous in the circumferential direction, and in the expanded state, the first annular member element is in the longitudinal axis direction. It includes three upper, lower, and lower linear elements that are parallel to each other. This linear element has a shorter middle linear element than the upper linear element, and a lower linear element shorter than the middle linear element. The elements are connected by arc-shaped elements protruding leftward, the middle linear element and the lower linear element are connected by a substantially S-shaped curved element, and the second annular member elements are parallel to each other in the longitudinal direction. The upper, middle, and lower three linear elements are included. The medium straight line element is shorter than the medium straight line element, and the lower straight line element is shorter than the medium straight line element. The upper straight line element and the middle straight line element are connected to each other by an arc-shaped element that protrudes to the right. The elements are connected by a substantially S-shaped curved element, and the first annular member element and the second annular member element are located on the second annular member element and the second annular member element. Between the first annular member element, the upper linear element of the second annular member element and the lower linear element of the first annular member element are connected to each other by an arc-shaped element protruding leftward, and the second annular element Between the member element and the first annular member element located below the second annular member element, the lower linear element of the second annular member element and the upper linear element of the first annular member element are to the right. Connected by convex arc-shaped elements, adjacent annular members are each curved elements Characterized by comprising coupled with the connecting portion between the lower linear element.

Here, the ratio of the length of the middle linear element to the upper linear element is preferably 3: 4 to 7: 8, and the ratio of the length of the lower linear element to the upper linear element is 1: 2. It is preferable to set it to ~ 3: 4. Further, adjacent annular members may be out of phase with each other, and in particular, those whose phases are shifted by ½ wavelength and connected by connecting elements on the same straight line in the longitudinal direction are preferable.
The shape of the connecting element may be a straight line or a curved line, and from the viewpoint of flexibility and formation of a horizontal hole, those having one or more wave peaks are particularly preferable.
In the annular member at the proximal end and the annular member at the distal end, the positions of the proximal end and the distal end of each linear element may be aligned. The linear elements of the first annular member element and the linear elements of the second annular member element may be arranged at equal intervals in the circumferential direction, and the interval between the upper linear element and the intermediate linear element is set to the lower linear line. The interval between the element and the upper linear element may be made equal, and the interval between the middle linear element and the lower linear element may be made larger than the interval.
As a material for forming the stent, stainless steel, tungsten, tantalum, nickel-titanium alloy and the like can be used.
Although the present invention has been generally described above, a better understanding can be obtained by reference to certain specific embodiments. These examples are provided herein for illustrative purposes only, and are not limiting unless otherwise specified.

According to the present invention, the following effects can be expected. That is, 1) Since the annular member constituting the tube wall of the stent has a repeated meandering pattern, the entire stent is flexible with respect to bending, and therefore has excellent followability to a lumen or the like. Moreover, it is easy to form a horizontal hole. 2) Since the adjacent annular members are connected at the portion connecting the curved element and the lower linear element, the ratio of the length of the middle linear element to the upper linear element is set to 3: 4 to 7: 8, If the ratio of the length of the lower linear element to the upper linear element is 1: 2 to 3: 4, the stent length is not substantially changed during expansion.

The ratio of the length of the lower linear element, middle linear element and upper linear element is 4: 7: 8, the phases of adjacent annular members are shifted by 1/2 wavelength, and connected by a connecting element on the same straight line in the longitudinal direction. To do. Further, the base end of the linear element of the base annular member and the tip of the linear element of the tip annular member are aligned.

First, Example 1 will be described with reference to FIGS.
FIG. 1 is a plan view of a stent according to an embodiment of the present invention, FIG. 2 is a developed view of the stent shown in FIG. 1, FIG. 3 is a plan view showing an expanded state of the stent shown in FIG. FIG. 3 is a partially enlarged view of FIG. 2.
As shown in FIGS. 1 to 3, the stent of Example 1 includes ten annular members 1 arranged in the longitudinal direction for keeping the living body lumen open, and annular members 1 adjacent in the longitudinal direction. 1 is a tubular member having three connecting elements 2 that connect one another, and the annular member 1 includes three first annular member elements 11 and three second elements that are continuous in the circumferential direction. It consists of an annular member element 12 and is expandable in the radial direction.

As shown in FIG. 2 and FIG. 4, the first annular member element 11 and the second annular member element 12 are continuous in the vertical direction in the expanded state, and the first annular member element 11 is The upper linear element 111 is longer than the intermediate linear element 112. The upper linear element 111 includes three upper, middle, and lower linear elements 111, 112, and 113 that are parallel to each other in the longitudinal direction and are arranged at equal intervals in the circumferential direction. The middle linear element 112 is longer than the lower linear element 113. The upper straight element 111 and the middle straight element 112 are connected by an arc-shaped element 114 protruding leftward, and the middle straight element 112 and the lower straight element 113 are connected by a substantially S-shaped curved element 115. ing.
On the other hand, the second annular member element 12 includes three linear elements 121, 122, and 123 having different lengths arranged in parallel in the circumferential direction at equal intervals in the circumferential direction. The straight line element 121 is longer than the middle straight line element 122, and the middle straight line element 122 is longer than the lower straight line element 123. The upper straight line element 121 and the middle straight line element 122 are connected by an arc-shaped element 124 convex leftward, and the middle straight line element 122 and the lower straight line element 123 are connected by a substantially S-shaped curve element 125. ing.

The first annular member element 11 and the second annular member element 12 are arranged between the second annular member element 12 and the first annular member element 11 located on the second annular member element 12. The upper linear element 121 of the second annular member element 12 and the lower linear element 113 of the first annular member element 11 are connected by the arc-shaped element 3 convex leftward, and the second annular member element 12 and this first Between the first annular member element 11 positioned below the two annular member elements 12, the lower linear element 123 of the second annular member element 12 and the upper linear element 111 of the first annular member element 11 are on the right. Are connected by a convex arc-shaped element 4.

The ratio of the lengths of the lower linear element 113 (123), the middle linear element 112 (122), and the upper linear element 111 (121) is 4: 7: 8. The adjacent annular members 1 and 1 are phase-shifted by a half wavelength, the portion connecting the curved element 115 and the lower linear element 113 of the first annular member element 11, and the second annular member element 12. A portion connecting the curved element 125 and the lower linear element 123 is connected by three connecting elements 2 having a shape as shown in FIG. 5A on the same straight line in the longitudinal direction.

In this device, the annular member constituting the tube wall of the stent is composed of a repeating meandering pattern of annular member elements (unit patterns), so that the entire stent is flexible with respect to bending, and therefore is capable of following a lumen or the like. Is excellent. Moreover, it is easy to form a horizontal hole. Further, the adjacent annular members are connected to each other by the arc-shaped element portion connecting the intermediate linear element having a short wavy pattern amplitude and the lower linear element, and the lower linear element 113 (123) and the intermediate linear element 112 are connected. The length ratio between (122) and the upper linear element 111 (121) is 4: 7: 8, and the stent length hardly changes during expansion. In addition, since the adjacent annular members are connected by the arc-shaped element portion that is the wave front of the wave pattern, there is no warping at the time of expansion at the wave front portion, and there is also little warping at the time of bending, so the site to which the stent is applied It is possible to minimize damage to blood vessels when guiding to the maximum.

A second embodiment of the present invention will be described with reference to FIG.
In the stent of Example 2, the length ratio of the lower linear element, the middle linear element, and the upper linear element is 6: 7: 8 in Example 1, and the proximal end side of the annular member 5 at the proximal end In the distal end side of the annular member 6 at the distal end, the positions of the base ends and the distal ends of the linear elements 111, 112, 113, 121, 122, 123 are aligned, and the connecting element 2 is shaped as shown in FIG. 5A. As shown in FIG. 6, it has ten annular members 1 (including 5, 6) that are radially expandable arranged in the longitudinal axis direction, and the adjacent annular members 1, 1 are The three wavy connecting elements 2 as shown in FIG. 5A are connected in the longitudinal direction.

The two ends of the stent are, in the annular member 5, the upper linear element 511 and the middle linear element 512 of the first annular member element 51, the proximal side of the lower linear element 513, and the upper linear element of the second annular member element 52. The proximal end sides of the first annular member elements 61 and the second annular member elements 62 are arranged at the proximal end positions of the stents. The distal ends of the upper linear element 621, the middle linear element 622, and the lower linear element 623 are lengthened and aligned with the distal end of the stent.
In the annular member 6, the arcuate element is aligned in the annular member 6 by shortening the middle linear element 612 and the lower linear element 613 of the first annular member element 61 toward the distal end side, and aligning it with the position of the distal end of the stent. In this case, the middle linear element 522 and the lower linear element 523 of the second annular member element 52 may be shortened to the proximal end side so as to be aligned with the proximal end position of the stent.

Similar to the one shown in Example 1, the entire stent is flexible with respect to bending, and therefore has excellent followability to a lumen or the like. Moreover, it is easy to form a horizontal hole. In addition, there is no warping at the time of expansion at the wave front, and there is little warping at the time of bending, so that damage to the blood vessel when guiding the stent to the application site can be avoided as much as possible. Further, the ratio of the lengths of the lower linear element, the middle linear element, and the upper linear element is 6: 7: 8, and the stent length hardly changes during expansion. In addition, since both ends of the stent are aligned, the irritation to the living body due to the unevenness of both ends during expansion is small.

A third embodiment of the present invention will be described with reference to FIG.
The stent of Example 3 is the same as that of Example 1 except that the shape of the connecting element 2 is corrugated as shown in FIG. 5B, and is expandable in the radial direction arranged in the longitudinal direction as shown in FIG. The adjacent annular members 1 and 1 are connected to each other in the longitudinal direction by three wavy connecting elements 2 as shown in FIG. 5B.
Similar to the one shown in the first embodiment, the entire stent is flexible with respect to bending, and therefore has excellent followability to a lumen or the like. Moreover, it is easy to form a horizontal hole. In addition, there is no warping at the time of expansion at the wave front, and there is little warping at the time of bending, so that damage to the blood vessel when guiding the stent to the application site can be avoided as much as possible. In addition, there is almost no change in the length of the stent during expansion.

A fourth embodiment of the present invention will be described with reference to FIG.
In the stent of Example 4, the distance between the middle linear element 112 (122) and the lower linear element 113 (123) in Example 1 is set between the upper linear element 111 (121) and the middle linear element 112 (122). 10 annular members that are twice the distance and the shape of the connecting element 2 is as shown in FIG. 5C and that are radially expandable as shown in FIG. The adjacent annular members 1 and 1 are connected in the longitudinal direction by three connecting elements 2 having a shape as shown in FIG. 5C.
Similar to the one shown in the first embodiment, the entire stent is flexible with respect to bending, and therefore has excellent followability to a lumen or the like. Moreover, it is easy to form a horizontal hole. In addition, there is no warping at the time of expansion at the wave front, and there is little warping at the time of bending, so that damage to the blood vessel when guiding the stent to the application site can be avoided as much as possible. In addition, there is almost no change in the length of the stent during expansion.

Embodiment 5 of the present invention will be described with reference to FIG.
In the stent of Example 5, in Example 1, the ratio of the lengths of the lower linear element, the middle linear element, and the upper linear element is 4: 6: 8, and the shape of the connecting element 2 is as shown in FIG. 5C. As shown in FIG. 9, it has ten annular members 1 that can be expanded in the radial direction arranged in the longitudinal direction, and the adjacent annular members 1, 1 are The three connecting elements 2 having a shape as shown in FIG. 5C are connected in the longitudinal axis direction.
Similar to the one shown in the first embodiment, the entire stent is flexible with respect to bending, and therefore has excellent followability to a lumen or the like. Moreover, it is easy to form a horizontal hole. In addition, there is no warping at the time of expansion at the wave front, and there is little warping at the time of bending, so that damage to the blood vessel when guiding the stent to the application site can be avoided as much as possible. In addition, there is almost no change in the length of the stent during expansion.

[Flexibility, shortening, and blood vessel diameter retention strength test] Stress analysis was performed on a stent having a developed view as shown in Table 1, and its flexibility (flexibility), shortening, and blood vessel diameter retention strength were compared. Results as shown in FIG. 12 were obtained.
FIG. 10 shows that the stent of the present invention has much more flexibility than the conventional stent. In addition, it can be seen from FIG. 11 that shortening during expansion can be prevented by appropriately selecting the height of the wave peak to be connected (depth of the valley). In addition, it can be seen from FIG. 12 that the blood vessel diameter retention strength is equivalent to that of a conventional stent.
As for the flexibility, the stent change amount (mm) when one end of the stent was fixed and a load (gf) was applied to the other end was analyzed.
As for shortening, the change in length when the stent was expanded to a diameter of 3.0 mm was analyzed. The graph shows the change rate of the stent length (length after expansion / length before expansion).
Regarding the blood vessel diameter retention force, the change amount (%) of the stent diameter when the stent was compressed (gf) was analyzed.

It is a top view of the stent which concerns on one Example of this invention. It is an expanded view of the stent shown in FIG. It is a top view which shows the state which expanded the stent shown in FIG. FIG. 3 is a partially enlarged view of FIG. 2. It is a figure which shows the Example of the connection element of this invention, and shows a connection state with an arc-shaped element. It is an expanded view of the stent which concerns on the other Example of this invention. It is an expanded view of the stent which concerns on the other Example of this invention. It is an expanded view of the stent which concerns on the other Example of this invention. It is an expanded view of the stent which concerns on the other Example of this invention. It is a figure which compares the softness | flexibility of the stent of this invention, and the conventional stent. It is a figure which compares the shortening of the stent of this invention, and the conventional stent. It is a figure which compares the blood vessel diameter retention strength of the stent of this invention, and the conventional stent. It is an expanded view of the conventional stent. It is an expanded view of the conventional stent. It is an expanded view of the conventional stent.

Explanation of symbols

Reference Signs List 1 annular member 11 first annular member element 111 upper linear element 112 middle linear element 113 lower linear element 114 arc-shaped element convex to the left 115 curved element 12 second annular member element 121 upper linear element 122 middle linear element 123 Lower linear element 124 Arc-shaped element convex to the right 125 Curve element 2 Connecting element 3 Arc-shaped element convex to the left 4 Arc-shaped element convex to the right 5 Base end annular member 511 Upper linear element 512 Middle linear element 513 Lower linear element 515 Curve element 6 Tip annular member 611 Upper linear element 612 Middle linear element 623 Lower linear element 625 Curve element

Claims (13)

A plurality of radially expandable annular members arranged in the longitudinal axis direction, and one or a plurality of curved connection elements that connect the adjacent annular members in the longitudinal axis direction; The first annular member element and the second annular member element are alternately continuous in the circumferential direction, and in the expanded state, the first annular member element is parallel to each other in the longitudinal direction. It includes three middle and lower straight line elements. The straight line element is shorter in the middle straight line element than the upper straight line element, and the lower straight line element is shorter than the middle straight line element. Connected by convex arc-shaped elements, the middle linear element and the lower linear element are connected by a substantially S-shaped curved element, and the second annular member elements are upper, middle, and lower parallel to each other in the longitudinal direction. Contains three linear elements, which are intermediate to the upper linear elements The line element is short, the lower straight line element is shorter than the middle straight line element, the upper straight line element and the middle straight line element are connected by an arc-shaped element convex to the right, and the middle straight line element and the lower straight line element are substantially S. The first annular member element and the second annular member element are connected by a curved curve element, and the first annular member element and the first annular member element are located on the second annular member element. Between the member elements, the upper linear element of the second annular member element and the lower linear element of the first annular member element are connected by a left-side convex arc-shaped element, and the second annular member element and the Between the first annular member element located below the second annular member element, the lower linear element of the second annular member element and the upper linear element of the first annular member element are arcuately convex to the right. The adjacent annular members are connected with each other with the respective curved elements and lower linear elements. Vascular trackability and expandability of superior flexible stent formed by connecting in connection portion. The stent according to claim 1, wherein the ratio of the length of the middle linear element to the upper linear element is 3: 4 to 7: 8. The stent according to claim 1, wherein the ratio of the length of the lower linear element to the upper linear element is 1: 2 to 3: 4. The stent according to any one of claims 1 to 3, wherein adjacent annular members are out of phase. The stent according to claim 4, wherein the phases of adjacent annular members are shifted by ½ wavelength, and the adjacent annular members are connected by a connecting element on the same straight line in the longitudinal direction. The stent according to any one of claims 1 to 5, wherein the shape of the connecting element is a straight line. The stent according to any one of claims 1 to 5, wherein the connecting element has a curved shape. The stent according to claim 7, wherein the connecting element is corrugated and has a wave peak. One wave mountain The stent according to claim 7, wherein the connecting element is corrugated and has a plurality of wave peaks. The stent according to any one of claims 1 to 9, wherein 2 to 6 connecting elements are provided at equal intervals. The stent according to any one of claims 1 to 10, wherein the proximal end and the distal end of each linear element are aligned in the proximal end annular member and the distal end annular member. The stent according to any one of claims 1 to 11, wherein the linear elements of the first annular member element and the linear elements of the second annular member element are arranged at equal intervals in the circumferential direction. The interval between the upper linear element and the intermediate linear element is made equal to the interval between the lower linear element and the upper linear element, and the interval between the intermediate linear element and the lower linear element is made larger than the interval. Item 12. The stent according to Items 1-11.

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