JP4569262B2 - Flexible stent with excellent blood vessel followability and expandability - Google Patents

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 comprises a plurality of radially extending annular members arranged in the longitudinal direction and a plurality of connecting elements that connect the adjacent annular members in the longitudinal direction. In the state where the annular member element is continuously repeated in the circumferential direction in a meandering pattern and developed, the annular member element has at least two kinds of wave patterns having different amplitudes. The center is on one wavy curve, and adjacent annular members are connected by a wave front having a small amplitude.

Here, the annular member element may include two wave crests having a large amplitude and one wave trough having a small amplitude. Even one having a small wave trough may have one wave crest having a large amplitude and two wave troughs having a small amplitude. Moreover, it is preferable that the ratio of the amplitude of a wave with a large amplitude and a wave with a small amplitude is 3: 5 to 9:10. The phases of the adjacent annular members may be shifted, and in particular, the phases of the 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. Is preferred.
The shape of the connecting element may be a straight line or a curved line. When the connecting element is a curved line, the shape is preferably wavy, and the number of wave peaks may be one or plural.
The positions of the arc-shaped elements may be aligned on the proximal end side of the proximal annular member and the distal end side of the distal annular member.

In the present invention, when the wave crest and wave trough of the annular member element are referred to, the wave crest (wave trough) of one annular member element is the other annular member with respect to the annular member elements adjacent in the circumferential direction. For convenience, a wave having a large amplitude is defined as a wave peak and a wave having a small amplitude is defined as a wave valley.
Further, stainless steel, tungsten, tantalum, nickel-titanium alloy, etc. can be used as the material for forming the stent.
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 is composed of a repeating meandering pattern of annular member elements (unit patterns), the entire stent is flexible with respect to bending, and therefore follows the lumen and the like. Is excellent. Moreover, it is easy to form a horizontal hole. 2) Since the adjacent annular members are connected to each other with a wave front having a small amplitude, there is substantially no change in the length of the stent during expansion. 3) Since the adjacent annular members are connected by wave-shaped wave fronts, there is no warping at the time of expansion at the wave front part, and there is little warping at the time of bending, so blood vessels when guiding the stent to the application site Can be avoided as much as possible.

The annular member element is composed of two crests of waves having a large amplitude and a trough of one wave having a small amplitude, and the ratio of the amplitudes of the waves having a small amplitude and the waves having a large amplitude is set to 4: 5. Are connected by a connecting element on the same straight line in the longitudinal direction with a phase shift of ½ wavelength.

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 11 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 is composed of six annular member elements 11 that are continuous in the circumferential direction, and can be expanded in the radial direction. ing.

As shown in FIGS. 2 and 4, the annular member element 11 includes two wave peaks 111 having a large amplitude and one wave valley 112 having a small amplitude. In the expanded state, the annular member element 11 repeatedly meanders in the vertical direction. It is continuous in a pattern. Further, as shown in FIG. 6, the center of the amplitude of the wave pattern of the annular member 1 is on one wavy curve CL, and the ratio of the amplitude of the small amplitude wave to the large amplitude wave is 4: 5. Yes. Adjacent annular members 1, 1 are out of phase by a half wavelength. The annular member 1 is composed of six annular member elements 11 that are continuous in the circumferential direction, and the adjacent annular members 1 and 1 are arranged on the same straight line in the longitudinal direction and have three shapes as shown in FIG. 5B. The connecting element 2 connects the wave valleys at the wave front 113.
As shown in FIG. 6, the wave front of the wave-like curve CL passing through the center of the amplitude of the wave pattern is collinear with the wave front 113 of the wave valley 112 having a small amplitude, and faces in the opposite direction to the wave front 113. Yes. That is, when the wave front 113 is convex to the right, the wave front of the wavy curve CL is convex to the left, and when the wave front 113 is convex to the left, the wave front of the wavy curve CL is convex to the right. Therefore, when the annular member 1 is expanded in the radial direction, the wave front 113 and the wave front of the wave curve CL move in the direction of the center line M from the opposite side with respect to the wave center line M of the wave curve CL. Since the movement and the movement of the wave-shaped curve CL (the movement of the entire annular member 1) are canceled out, shortening can be prevented by appropriately selecting the ratio of the amplitude of the wave with a small amplitude and the wave with a large amplitude. .

In this device, since the annular member constituting the tube wall of the stent is composed of repeated wavy patterns, 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, the adjacent annular members are connected at the crest of the wave trough, and the ratio of the amplitude of the small amplitude wave to the large amplitude wave is 4: 5, which is the length of the stent during expansion. There is no change. In addition, since the adjacent annular members are connected with wave-shaped wave fronts, there is no warping at the time of expansion at the wave front part, and there is little warping at the time of bending, so that the blood vessel of the blood vessel when guiding the stent to the application site is reduced. Damage can be avoided as much as possible.

A second embodiment of the present invention will be described with reference to FIG.
In the stent of Example 2, the ratio of the amplitude of the small amplitude wave to the large amplitude wave is 7: 8 in Example 1, and the proximal end side of the proximal end annular member 3 and the distal end annular member 4 On the tip side, the wave crest 111 and the wave trough 112 are aligned, and the connecting element 2 is shaped as shown in FIG. 5E, and the radii arranged in the longitudinal axis direction as shown in FIG. It has 11 annular members 1 (including 3 and 4) that are expandable in the direction. The annular member 1 is composed of six annular member elements 11 that are continuous in the circumferential direction, and the adjacent annular members 1 and 1 are connected in the longitudinal axis direction by three undulating connecting elements 2 as shown in FIG. 5E. Has been.

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 minimized. The ratio of the amplitude of the small amplitude wave to the large amplitude wave is 7: 8, and there is almost no change in the length of the stent 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 a corrugated shape as shown in FIG. 5D, and is expandable in the radial direction arranged in the longitudinal direction as shown in FIG. 11 eleven annular members 1 are provided. The annular member 1 is composed of six annular member elements 11 that are continuous in the circumferential direction, and the adjacent annular members 1 and 1 are connected in the longitudinal axis direction by three undulating connecting elements 2 as shown in FIG. 5D. Has been.
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, the stent length does not change during expansion.

A fourth embodiment of the present invention will be described with reference to FIG.
In the stent of Example 4, the annular member element 11 in Example 1 is composed of one wave peak 111 having a large amplitude and one wave valley 112 having a small amplitude, and a wave having a small amplitude and a wave having a large amplitude. The ratio of the amplitude of the connecting element 2 is 3: 5, and the shape of the connecting element 2 is as shown in FIG. 5C. As shown in FIG. The annular member 1 is provided. The annular member 1 includes eight annular member elements 11 that are continuous in the circumferential direction, and the adjacent annular members 1 and 1 are four connecting elements 2 having a shape as shown in FIG. 5C in the longitudinal axis direction. It is connected.
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, a horizontal hole can be formed. 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, since the ratio of the amplitude of the small amplitude wave to the large amplitude wave is reduced to 3: 5, the amplitude of the wavy curve CL increases, and accordingly, the wave that moves in the opposite direction to the movement of the wave front of the wavy curve CL. Since the movement of the valley 112 becomes larger, the largest shortening occurred in the embodiment during expansion.

A fifth embodiment of the present invention will be described with reference to FIG.
The stent of Example 5 is the same as Example 4 except that the ratio of the amplitude of the small amplitude wave to the large amplitude wave is 4: 5, and the shape of the connecting element 2 is as shown in FIG. 5B. As shown in FIG. 10, it has eleven annular members 1 radially expandable arranged in the longitudinal axis direction. The annular member 1 is composed of eight annular member elements 11 that are continuous in the circumferential direction, and the adjacent annular members 1 and 1 are four connecting elements 2 having a shape as shown in FIG. 5B in the longitudinal axis direction. It is connected.
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, a slight shortening occurred in the length of the stent during expansion.

A sixth embodiment of the present invention will be described with reference to FIG.
In the stent of Example 6, the annular member element 11 in Example 1 is composed of one wave crest having a large amplitude and two wave troughs having a small amplitude, and the shape of the connecting element 2 is as shown in FIG. 5D. As shown in FIG. 11, it has eleven annular members 1 which are arranged in the longitudinal direction and expand in the radial direction. The annular member 1 is composed of six annular member elements 11 that are continuous in the circumferential direction. Adjacent annular members 1 and 1 are composed of six connecting elements 2 having a shape as shown in FIG. 5D in the longitudinal axis direction. It is connected. This is inferior to that shown in Example 1, but the entire stent is flexible with respect to bending, and therefore has excellent followability to a lumen or the like. Moreover, a horizontal hole can be formed. 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, a slight shortening occurred in the length of the stent during expansion.

A seventh embodiment of the present invention will be described with reference to FIG.
The stent of Example 7 is the same as Example 6 except that the ratio of the amplitude of the small amplitude wave to the large amplitude wave is 7: 8, and the shape of the connecting element 2 is as shown in FIG. 5A. Yes, as shown in FIG. 12, it has eleven annular members 1 radially expandable arranged in the longitudinal axis direction. The annular member 1 includes six annular member elements 11 that are continuous in the circumferential direction, and the adjacent annular members 1 and 1 are connected in the longitudinal axis direction by six connecting elements 2 having a shape as shown in FIG. 5A. Has been. Similar to that shown in Example 6, this stent is flexible with respect to bending, and therefore has excellent followability to a lumen or the like. Moreover, a horizontal hole can be formed. 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, a slight shortening occurred in the length of the stent during expansion.

[Flexibility, shortening, and blood vessel diameter holding force 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 holding force were compared. Results as shown in FIG. 15 were obtained.
From FIG. 13, it can be seen that the stent of the present invention has much more flexibility than the conventional stent. Moreover, it can be seen from FIG. 14 that shortening during expansion can be prevented by appropriately selecting the height of the wave peak to be connected (depth of the valley). Further, FIG. 15 shows that the blood vessel diameter holding force shows the same performance as that of the conventional stent.
For 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.
For shortening, changes in length when the stent was expanded to a diameter of 3.0 mm were analyzed. The graph shows the change rate of the stent length (length after expansion / length before expansion).
Regarding the blood vessel diameter retention force, changes in the stent diameter when the stent was compressed were 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 the connection state of an annular member. In FIG. 1, it is a figure which shows the wavy curve which passes along the center of the wave pattern of a stent. 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 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

DESCRIPTION OF SYMBOLS 1 Ring member 11 Ring member element 111 Wave peak 112 Wave valley 113 Wave valley peak 2 Connection element 3 Base ring member 4 Tip ring member CL Wave curve M Center line of wave curve

Claims (12)

A plurality of annular members radially expandable arranged in the longitudinal axis direction, and a plurality of connecting elements that connect adjacent annular members in the longitudinal axis direction, the annular member comprising: The annular member element has at least two types of wave patterns with different amplitudes in a state where the meander pattern is repeated in the circumferential direction and expanded, and the center of the amplitude of the wave pattern is one. A flexible stent excellent in blood vessel followability and expandability, which is formed on a wavy curve and in which adjacent annular members are connected to each other by a wave front having a small amplitude wave pattern. The stent according to claim 1, wherein the annular member element has two wave peaks having a large amplitude and one wave valley having a small amplitude. The stent according to claim 1, wherein the annular member element has one wave crest having a large amplitude and one wave trough having a small amplitude. The stent according to claim 1, wherein the annular member element has one wave crest having a large amplitude and two wave valleys having a small amplitude. The stent according to any one of claims 2 to 4, wherein a ratio of an amplitude of a wave having a large amplitude to a wave having a small amplitude is 3: 5 to 9:10. The stent according to any one of claims 1 to 5, 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 7, wherein the shape of the connecting element is a straight line. The stent according to any one of claims 1 to 7, wherein the connecting element has a curved shape. The stent according to claim 9, wherein the connecting element is corrugated and has one wave crest. 11. The stent according to claim 10, wherein the connecting element is wave-shaped and has a plurality of wave peaks. The stent according to any one of claims 1 to 11, wherein the positions of the arc-shaped elements are aligned on the proximal end side of the proximal annular member and the distal end side of the distal annular member.

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