WO2006035669A1

WO2006035669A1 - Soft stent excellent in vascular follow-up and dilation nature

Info

Publication number: WO2006035669A1
Application number: PCT/JP2005/017480
Authority: WO
Inventors: Yoshihiko Sano; Yuji Tanaka; Yukinori Ebara
Original assignee: Nipro Corporation
Priority date: 2004-09-28
Filing date: 2005-09-22
Publication date: 2006-04-06

Abstract

A soft stent having excellent follow-up nature to lumens (accordingly, allowed to pass the lumens meandering three-dimensionally), substantially preventing shortening from occurring, and enabling a lateral hole to be formed therein. An annular member (1) comprises ten wave-like elements (11) continued in the circumferential direction so as to be expanded in the radial direction. The wave-like element (11) comprises the crest (111) of one wave and the bottom of (112) of the one wave. In the developed state of the wave-like elements, the wave-like elements continuously form a repeated meandering pattern in the vertical direction. The annular members (1) and (1) adjacent to each other are connected to each other on the longitudinal same straightline, and the waves connected to each other through connection elements (2) are formed in the crest (113) thereof and the other is formed in the bottom (114) thereof. The crest (113) and the bottom (114) of the wave are so formed that the amplitudes of the wave are reduced relative to each other only at these portions, which is 2/3 of the amplitudes of the crest (111) and the bottom (112) of the wave not connected to each other through the connection elements (2).

Description

Specification

Flexible stent with excellent blood vessel followability and expandability

Technical field

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.

Background art

Conventionally, a stent has been adopted in order to expand the diameter of a lumen of a blood vessel or the like and maintain the size of the obtained lumen. Stent expansion methods include balloon expansion, self-expansion using shape memory materials, and mechanical expansion, but expansion using nolane is common. In the case of balloon expansion, the stent is introduced to a desired position on the body together with a non-renal catheter, and is expanded by balloon inflation to expand the lumen diameter. The stent usually has a lumen diameter holding portion that expands and holds the lumen diameter of a blood vessel and the like, and a joint portion force that connects them in the longitudinal direction, and the expanded shape is maintained.

As such a stent having a lumen diameter holding part and a joint part force, 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). Or a radially extending tubular member formed by a plurality of elongated members intersecting each other (Patent Document 2), or a plurality of substantially connected integrally at the axial bending portion. A straight and overlapping structure comprising at least two single wire-like circular members bent so as to form a segment, and the circular members are firmly connected to each other by a shaft bending portion (Patent Document 3), Consists of a tube with a pattern shape having first and second meander patterns having axes extending in the first and second directions (Patent Document 4), and a plurality of cylindrical segments are gathered by interconnecting elements in oblique directions. The ends are joined Those posts or Ranaru open structure type is (Patent Document 5), and the proposed! Ru.

[0003] However, these conventional stents have been improved! Because the stent still loads the lumen of a blood vessel or the like in the vicinity of the stent edge when expanded. Occlusion and stenosis of the lumen and the like may occur. In addition, since it cannot be said that it has sufficient flexibility, when the lumen or the like meanders three-dimensionally, the target site is scanned. Sometimes it was difficult to carry a tent. In addition, blood vessels may be damaged when the stent is delivered 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.

Patent Document 1: Japanese Patent Laid-Open No. 6-181993

Patent Document 2: Japanese Patent Laid-Open No. 62-231657

Patent Document 3: Japanese Patent Laid-Open No. 8-155035

Patent Document 4: Japanese Unexamined Patent Publication No. 10-503676

Patent Document 5: Japanese Patent Publication No. 11-505441

Disclosure of the invention

Problems to be solved by the invention

[0005] 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 substantially causes shortening. The present invention provides a flexible stent having excellent extensibility and capable of forming a lateral hole in a stent. Means for solving the problem

[0006] The stent of the present invention comprises a plurality of radially expandable annular members arranged in the longitudinal axis direction and a plurality of connecting elements that connect the adjacent annular members in the longitudinal axis direction. In the annular member, a wave element consisting of one wave crest and one wave trough force is continuously repeated in a meandering pattern in the circumferential direction, and adjacent annular members are adjacent to the wave front of the wave element or the wave element. The wave-like elements are connected to each other in the vicinity of the wave front, and in the unfolded state, the wave-like wave connected by the connection element has a relatively small amplitude.

[0007] Here, the connection between the adjacent annular members can be arbitrarily determined, but specifically, the connection between the adjacent annular members is preferably performed every even number of the wave elements. Preferably, every other, four or every six wavy elements are carried out. And it is preferable that the wave fronts connected by the connecting elements of the adjacent annular members are positioned on the same straight line in the longitudinal direction. In addition, the amplitude of the waves connected by the connecting elements that are preferably connected on the same straight line in the longitudinal direction between adjacent annular members does not substantially cause shortening when the stent is expanded. , Waves not connected by connecting elements Preferably, the amplitude is 1: 2 to 7: 8. In addition, in order to improve flexibility, the amplitude of the wave connected by the connecting element is reduced, and in order to reduce the shortening at this time, the wavelength of the wave connected by the connecting element is the wavelength not connected by the connecting element. (The longer the coupling element, the better the flexibility. However, if the amplitude is reduced to make the coupling element longer, the shortening during expansion will increase).

The shape of the connecting element can be either a straight line or a curved line.If the connecting element is a curved line, even if there is only one wave peak that is preferred to be wavy, There can be one or more waves, and there can be multiple peaks and valleys.

[0008] As a material for forming the stent, stainless steel, tungsten, tantalum, nickel titanium alloy and the like can be employed.

Further, in the present invention, for convenience, a wave peak means a wave convex right (convex to the tip side), and a wave valley means a wave convex left (convex to the base end side).

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.

The invention's effect

According to the present invention, the following effects can be expected. That is, 1) The annular member constituting the tube wall of the stent also has a meandering pattern force of the wavy element (unit pattern), so the entire stent is flexible to bending, and therefore follows the lumen etc. Excellent in properties. Also, it is easy to form a horizontal hole. 2) Since the adjacent annular members are connected by a wave front having a relatively small amplitude, there is substantially no change in the length of the stent during expansion. 3) Since the adjacent annular members are connected with wave-shaped wave fronts, there is no warping during expansion at the wave front part, and there are also few warpings during bending, so the blood vessels when guiding the stent to the application site Can be avoided as much as possible. Brief Description of Drawings

FIG. 1 is a plan view of a stent according to an embodiment of the present invention.

FIG. 2 is a development view of the stent shown in FIG. 1. FIG. 3 is a plan view showing a state where the stent shown in FIG. 1 is expanded.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is a view showing an example of a connecting element according to the present invention, showing a connected state of annular members.

FIG. 6 is a development view of a stent according to another embodiment of the present invention.

FIG. 7 is a development view of a stent according to another embodiment of the present invention.

FIG. 8 is a development view of a stent according to another embodiment of the present invention.

FIG. 9 is a development view of a stent according to another embodiment of the present invention.

FIG. 10 is a development view of a stent according to another embodiment of the present invention.

FIG. 11 is a development view of a stent according to another embodiment of the present invention.

FIG. 12 is a development view of a stent according to another embodiment of the present invention.

FIG. 13 is a diagram comparing the flexibility of the stent of the present invention and a conventional stent.

FIG. 14 is a diagram comparing the shortening of the stent of the present invention and a conventional stent.

FIG. 15 is a diagram comparing the blood vessel diameter retention of the stent of the present invention and a conventional stent.

FIG. 16 is a development view of a conventional stent.

FIG. 17 is a development view of a conventional stent.

FIG. 18 is a development view of a conventional stent.

Explanation of symbols

[0011] 1 annular member

11 Annular element

111 Wave Mountain

112 Wave Valley

113 Waves connected by connecting elements

114 Wave Valley Connected by Connecting Elements

2 Connected elements

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] The connection between the adjacent connection members is made every four wave-like elements, and the wave fronts of the wave-like elements connected between the adjacent annular members of the wave-like elements are positioned on the same straight line in the longitudinal direction. The adjacent annular members are connected on the same straight line in the longitudinal direction. Ma The amplitude of the wave connected by the connecting element shall be 2Z3 of the amplitude of the wave not connected by the connecting element. Also, the wavelength of the wave connected by the connecting element should be twice that of the wave not connected by the connecting element.

Example 1

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 development 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 an enlarged view of a part of FIG.

As shown in FIGS. 1 to 3, the stent of Example 1 includes 10 annular members 1 arranged in the longitudinal direction for keeping the living body lumen open, and adjacent annular members 1 and 1. Is a tubular member having two connecting elements 2 in the longitudinal direction, and the annular member 1 is composed of ten wavy elements 11 continuous in the circumferential direction, and is expandable in the radial direction. ing. In addition, the wavelength of the wave connected by the connecting element 2 is twice the wavelength of the wave not connected by the connecting element 2.

[0014] As shown in FIG. 2 and FIG. 4, the wavy element 11 is composed of one wave peak 111 and one wave valley 11 2, and in the expanded state, the wavy element 11 has a repeated meandering pattern. It is continuous. The adjacent annular members 1 and 1 are connected by two connecting elements 2 having the shape shown in FIG. 5A on the same straight line in the longitudinal direction, and the wave connected by the connecting element 2 is One becomes the Wave Mountain 113 and the other becomes the Wave Valley 114. The wave peak 113 and the wave valley 114 connected by the connecting element 2 have a relatively small wave amplitude, and the wave peak 111 and the wave valley 112 are not connected by the connecting element 2. The amplitude becomes 2Z3. In addition, the wavelength of the wave connected by connecting element 2 is twice that of the wave not connected by connecting element 2.

[0015] Since this is composed of a repeating wave pattern of the annular member force constituting the tube wall of the stent, the entire stent is flexible with respect to bending, and therefore has excellent followability to the lumen and the like. . Moreover, it is easy to form a horizontal hole. In addition, adjacent annular members are connected by wave heads with reduced amplitude, and the ratio of the amplitude of the small amplitude wave to the large amplitude wave is 2: 3, and is connected by connection element 2. Wavelength of wave that is not connected by connecting element 2 When expanded, it is slightly longer, but there is almost no change in the length of the stent. Adjacent annular members are connected by wave-shaped wave fronts between adjacent annular members. It is possible to minimize the damage of blood vessels during the process.

Example 2

[0016] A second embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 6, the stent of Example 2 has 11 annular members 1 and three connecting elements 2 each having two wavy elements and having a shape as shown in FIG. 5B. The annular member 1 is composed of nine corrugated elements 11 that are continuous in the circumferential direction. The ratio of the amplitude of the wave connected by connecting element 2 to the amplitude of the wave not connected by connecting element 2 is 4Z5.

Similar to that shown in the first embodiment, there is no warp during expansion at the wave front portion. In addition, there is almost no change in the length of the stent during expansion. In addition, since there is little warping at the time of bending, damage to the blood vessel when guiding the stent to the application site can be minimized. It is easy to form a horizontal hole. Since the number of connecting elements is large, the flexibility 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.

Example 3

Example 3 of the present invention will be described with reference to FIG.

As shown in FIG. 7, the stent of Example 3 has 11 annular members 1 and three connecting elements 2 having a shape as shown in FIG. 5D provided for every three wavy elements. The annular member 1 is composed of twelve wavy elements 11 that are continuous in the circumferential direction. The ratio of the wave amplitude connected by connecting element 2 to the wave amplitude not connected by connecting element 2 is 7: 8.

Similar to the one shown in Example 1, 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. . The shortening during expansion is slightly inferior to that shown in Example 1. The flexibility is slightly better than Example 2 with the same number of connecting elements. Example 4

Example 4 of the present invention will be described with reference to FIG.

As shown in FIG. 8, the stent of Example 4 has ten annular members 1 and three connecting elements 2 having a shape as shown in FIG. 5B provided for every four wavy elements. The annular member 1 is composed of 15 corrugated elements 11 continuous in the circumferential direction. The ratio of the wave amplitude connected by connecting element 2 to the wave amplitude not connected by connecting element 2 is 3: 5.

Similar to the one shown in Example 1, 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. . There is almost no shortening during expansion. Flexibility is almost the same as Example 1 despite the large number of connecting elements Example 5

Example 5 of the present invention will be described with reference to FIG.

As shown in FIG. 9, the stent of Example 5 has ten annular members 1 and two connecting elements 2 having a shape as shown in FIG. 5A provided for every six wavy elements. The annular member 1 is composed of 14 corrugated elements 11 continuous in the circumferential direction. The ratio of the amplitude of the wave connected by connecting element 2 to the amplitude of the wave not connected by connecting element 2 is 3: 4.

Similar to the one shown in Example 1, 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. . The shortening during expansion is slightly better than that shown in Example 1. The flexibility is also slightly better than in Example 1 where the number of connecting elements is equal.

Example 6

Example 6 of the present invention will be described with reference to FIG.

As shown in FIG. 10, the stent of Example 6 has 11 annular members 1 and two connecting elements 2 each having two wavy elements and having a shape as shown in FIG. 5A. The annular member 1 is composed of six corrugated elements 11 continuous in the circumferential direction. The ratio of the wave amplitude connected by connecting element 2 and the wave amplitude not connected by connecting element 2 is 3: 5. Similar to the one shown in Example 1, there is no warping when expanding at the wave front, and there is little warping at the time of bending, so damage to the blood vessel when guiding the stent to the application site can be avoided as much as possible. . The shortening at the time of expansion is slightly longer like that shown in the first embodiment. The flexibility is slightly inferior to Example 1 with the same number of connecting elements.

Example 7

Example 7 of the present invention will be described with reference to FIG.

As shown in FIG. 11, the stent of Example 7 has eight annular members 1 and four connecting elements 2 having a shape as shown in FIG. 5C provided every two wavy elements. The annular member 1 is composed of twelve wavy elements 11 that are continuous in the circumferential direction. The ratio of the amplitude of the wave connected by connecting element 2 and the connecting element 2 is not !, the ratio of the amplitude of the wave is 5: 6!

Similar to the one shown in Example 1, 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. . The shortening at the time of expansion is the same as that shown in the third embodiment. Although the number of connecting elements is large, the flexibility is better than that shown in Example 2 because of the long connecting elements. Therefore, the entire stent is flexible with respect to bending, and therefore has excellent followability to a lumen or the like. Example 8

Example 8 of the present invention will be described with reference to FIG.

As shown in FIG. 12, the stent of Example 8 has eight annular members 1 and two connecting elements 2 having a shape as shown in FIG. 5D provided for every three wavy elements. The annular member 1 is composed of eight wavy elements 11 that are continuous in the circumferential direction. The ratio of the wave amplitude connected by connecting element 2 to the wave amplitude not connected by connecting element 2 is 7: 8.

Similar to the one shown in Example 1, 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. . Regarding the shortening at the time of expansion, the worst in the examples is good. The flexibility is the best as in Example 5 with the same number of connecting elements. [0023] [Flexibility, shortening, and blood vessel diameter retention test]

Stresses were analyzed for stents with development views as shown in Table 1, and their flexibility (flexibility), shortening, and vessel diameter retention were compared. The results shown in Figs. Obtained.

From FIG. 13, it can be seen that the stent of the present invention has much better flexibility than the conventional stent. In addition, it can be seen from Fig. 14 that shortening during expansion can be prevented by appropriately selecting the height of the wave peaks (valley depth) to be connected. In addition, it can be seen from FIG. 15 that the blood vessel diameter retention strength is equivalent to that of the conventional stent.

For flexibility, we analyzed the amount of stent change (mm) when one end of the stent was fixed and a load of 1N was applied to the other end. The values in the graph show the analysis value (mm) divided by the individual stent length (mm). For shortening, we analyzed the change in length when the stent was expanded to a diameter of 3.0 mm. The graph shows the change rate of the stent length. Regarding the vessel diameter retention force, the change (mm) in stent diameter when the stent was compressed (pressure: lOOmmHg) was analyzed. The values in the graph show the ratio with the stent diameter before compression.

[0024] [Table 1]

Remarks

Example 1 Fig. 2 (Number of annular members: 10, number of wavy elements: 10, number of connecting elements: every 4 wavy elements = 2; amplitude ratio is 2: 3, connected Wave wavelength: Twice the wavelength of unconnected wave, shape of connecting element: Fig. 5 A) Example 2 Fig. 6 (number of annular members: 1 1 piece, number of wavy elements: 9 pieces, connecting element Number of undulating elements: Every other 2 = 3, Amplitude ratio is 4: 5, Shape of connecting element: Fig. 5 B) Example 3 Fig. 7 (Number of annular members: 1 1 Number of undulating elements: 1 2 pieces, number of connecting elements: every 3 wave elements = 3 pieces, amplitude ratio 7: 8, shape of connecting elements: Fig. 5 D) Example 4 Fig. 8 (number of annular members: 10 pieces, Number of wavy elements: 1 5; Number of connecting elements: Every 4 wavy elements = 3; Amplitude ratio is 3: 5; Shape of connecting elements: Fig. 5 B) Example 5 Fig. 9 (of annular member) Number: 1 0, Number of wavy elements: 14 Number of connected elements: Wavy elements 6 pieces = 2 pieces, Amplitude ratio is 3: 4, Shape of connecting element: Fig. 5 A) Example 6 Fig. 10 (Number of annular members: 1 1 piece, Number of wavy elements: 6 pieces, Connecting element) Number: 2 wavy elements = 2; Amplitude ratio is 3: 5; Shape of connecting element: Fig. 5 A) Example 7 Fig. 1 1 (Number of annular members: 8; Number of wavy elements: 1 2 pieces, number of connecting elements: every other wavy element = 4 pieces, amplitude ratio 5: 6, shape of connecting elements: Fig. 5 C) Example 8 Fig. 1 2 [Number of annular members: 8 pieces Number of wavy elements: 8, Number of connecting elements: Every 3 wavy elements = 2, Amplitude ratio is 7: 8, Shape of connecting elements: Fig. 5D) Comparative example 1 Fig. 1 6 [Consists of waveform pattern Comparative example 2 Fig. 17 (Joint wave head and bottom of corrugated blood vessel diameter holding part) Comparative example 3 Fig. 18 [Condition of corrugated blood vessel diameter holding part and corrugated joint element) Joint wave heads together)

Claims

The scope of the claims

[I] It includes a plurality of radially expandable annular members arranged in the longitudinal axis direction and a plurality of connecting elements that connect the adjacent annular members in the longitudinal axis direction. A wave element consisting of one wave crest and one wave valley is repeated in the circumferential direction in a continuous meander pattern, and adjacent annular members are adjacent to the wave head of the nearest wave element or the wave front. In a state where the parts are connected to each other and deployed, the wave-like element is a flexible, excellent blood vessel following property and expandability, in which the amplitude of the wave connected by the connecting element is relatively reduced. Stent.

[2] The stent according to claim 1, wherein the adjacent annular members are connected to each other even-numbered wavy elements.

[3] The stent according to claim 2, wherein the adjacent annular members are connected every two, four, or six wavy elements.

4. The stent according to claim 1 or 2, wherein wave fronts connected by connecting elements between adjacent annular members are located on the same straight line in the longitudinal direction.

5. The stent according to any one of claims 1 to 4, wherein adjacent annular members are connected on the same straight line in the longitudinal direction.

[6] Wave amplitude connected by connecting element is not connected by connecting element !, 1Z2 ~ 7 of wave amplitude

The stent according to any one of claims 1 to 5, which is Z8.

7. The stent according to any one of claims 1 to 6, wherein the wavelength of the wave connected by the connecting element is larger than the wavelength of the wave not connected by the connecting element.

8. The stent according to any one of claims 1 to 7, wherein the shape of the connecting element is a straight line.

9. The stent according to any one of claims 1 to 7, wherein the shape of the connecting element is a curve.

10. The stent according to claim 9, wherein the connecting element is corrugated and has one wave crest.

[II] The stent coupling element according to claim 9, wherein the coupling element is corrugated and has one wave crest and wave trough, and has a plurality of wave crests and wave troughs. The stent according to claim 9.