A flexible expandable stent

FIELD OF THE INVENTION

The present invention relates to implantable stents in a living organism.

Background of the invention

Various stents are known, in which case the term "stent" refers to prostheses made of a material acceptable to a living organism that is used to dilate blood vessels or other intracorporeal pathways and to maintain the lumen size achieved as a result of the dilation. Typically, the stent is placed at a desired location in the body with an inflatable balloon. As the balloon fills, the stent expands, at the same time expanding the path. In addition to balloons, other mechanical devices are used to expand the stents.

For example, wire stents are disclosed in U.S. Patent Nos. 5,019,090 (Pinchuk), No. 5,161,547 (Tower), No. 4,950,227 (Savin et al.), No. 5,314,472 (Fontaine), No. 4,886,062, and No. 4,969,458. (Wiktor) and No. 4,856,516 (Hillstead). Stents made by cutting out of raw metal material are disclosed in U.S. Pat

733 665 (Palmaz), No. 4,762,128 (Rosenbluth), No. 5,102,417 (Palmaz and Schatz), No.

195 984 (Schatz) and WO 91 FR013820 (Meadox).

The expandable tubular implants of the stents disclosed in U.S. Patent No. 5,102,417 (Palmaz and Schatz) are connected to each other by flexible connectors. The implants have a number of slits parallel to the longitudinal axis of the tube. The flexible connectors have a helical shape.

Because tubular implants are relatively rigid, the purpose of the flexible connectors is to ensure that the stent bends as it is delivered through a tortuous vessel. As the stents described in U.S. Pat. No. 5,102,417 expand, the implants expand radially and therefore shorten longitudinally. However, at the same time, the helical connectors twist, which is probably detrimental to the blood vessel.

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U.S. Pat. No. 5,195,984 (Schatz) discloses an analogous stent having only one straight connector running between tubular implants parallel to their longitudinal axis. The straight connector does not twist, but at the same time cannot ensure strong enough connections.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a flexible stent which, when expanded, shortens minimally in the longitudinal direction.

The stent according to the present invention is made of a patterned tube with the axes of the first and second meander patterns extending in the first and second directions, the second meander patterns intertwining with the first meander patterns. The first and second directions may be at right angles to each other.

According to one embodiment of the present invention, the first meander patterns are formed as right and left first meander patterns. The right and left first meander patterns are rotated 180 degrees relative to each other (the left pattern is a mirror image of the right pattern), and the left patterns are located between the two right patterns. These other meander patterns can also be formed from right and left patterns.

In addition, according to a preferred embodiment of the present invention, the second meander patterns have two loops per period, and the right and left first meander patterns are connected to each loop of the second meander pattern on its first and second sides, respectively.

Alternatively or in addition, the other meander patterns are formed of right and left second meander patterns. In such a solution, the first right and left meander patterns have loops and the right and left second meander patterns are connected to the right and left first meander patterns.

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According to a preferred embodiment of the present invention, the first and second meander patterns are made of sheet metal. Alternatively, wire can be used to make them. The finished patterns can be placed in or covered with any material suitable for a living organism.

Brief description of the drawings

A clearer and more comprehensible picture of the present invention is provided by the following detailed description with drawings, in which:

- FIG. 1 shows a patterned stent fabricated and operative in accordance with a first preferred embodiment of the present invention;

- FIG. 2 is shown in FIG. 1;

in FIG. 3 is shown in FIG. 1 in the bent position;

- FIG. 4 is shown in FIG. 1 in an expanded form,

- FIGS. 5A and 5B show the changes due to expansion in FIG. 1;

- FIG. 6 is a schematic representation of a second embodiment of a stent pattern;

- FIG. 7 shows a third embodiment of a stent pattern; and FIG. 8 is shown in FIG. 7 in an expanded form.

Detailed Description of the Preferred Embodiments 25

Referring now to FIGS. 1-4 based on a stent according to the first embodiment, which is manufactured and functions according to the principles of the present invention. In FIG. 1 shows the stent in an unexpanded form, FIG. 2 shows a stent pattern, FIG. 3 shows the stent in a partially bent position, and FIG. 4 - in expanded form.

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The stent of the present invention is a tube having a side surface formed of a plurality of two types of meander patterns intertwined at right angles to each other. The term "meander pattern" as used herein refers to a periodic pattern meandering about a central axis, and "rectangular meander patterns" are patterns whose central axes are at right angles to each other.

In FIGS. 1-4, the two meander patterns are indicated by the numbers 11 and 12 and are most clearly seen in FIG. 2. The meander pattern 11 is a vertical sinusoid with a vertical central axis 9. The meander pattern 11 has two eyelets, 14 and 16, per period, with the eyelet 14 opening to the right and the eyelet 16 to the left. The eyelets 14 and 16 have common elements 15 and 17, the element 15 connects the eyelet 14 to the next eyelet 16 and the element 17 to the eyelet 16 following the eyelet 14.

The meander pattern 12 is a horizontal pattern with a horizontal central axis 13. The meander pattern 12 also has eyelets, indicated by the numbers 18 and 20 in the figure, but the eyelets of each period are separated by a long straight section, indicated by the number 22. The eyelets 18 open down, the eyelets 20 up. The vertical meander pattern 11 is divided into left and right meander patterns (o and e) rotated 180 degrees relative to each other (mirror image). Thus, the left-handed eyelets 16 of the meander patterns 10 are opposite the right-handed eyelets 14 of the meander patterns, and the right-handed eyelets 14 of the meander patterns 11 are in turn opposite the left-handed eyelets 16 of the meander pattern 11.

The horizontal meander patterns 12 are also divided into right and left.

The straight sections 22 of the horizontal meander pattern 12e intersect with each of the third common elements 17 of the vertical meander pattern. The straight sections 22 of the horizontal meander pattern 12o intersect with each of the third common elements A complete loop between 12o

14 and an integral loop 16 between the meander patterns 12o and 12e.

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According to FIG. 1 is formed in FIG. 2 into a tube 30 made of a slightly deformable material, such as metal. Due to the two meander patterns in FIG. 1 is attached to the balloon catheter due to the flexibility of the design and is therefore easy to pull through the tortuous vessels. In FIG. 3 shows FIG. 1.

In FIG. 3 begins to bend at the location indicated by the letter A, in the direction indicated by the arrow 40. When the stent bends, the section marked I appears on the inside of the bent part and the section marked O on the outside of the bent part. The shortening of the inner side I of the bent part is accompanied by the elongation of its outer side O.

To compensate for the difference in inside and outside lengths, the shape of the eyelets 14 to 20 to the right of point A changes. For example, the eyelets 181 and 20i on the inside of the bent portion are more closely together than the eyelets 18o and 20o on the outside of the bent portion as a result of bending. As a result of the bending, the eyelets 14i and 16i near the inner side I are compressed, while the eyelets 14o and 16o on the outer side are stretched apart.

As can be seen, both the vertical 11 and the horizontal 12 meander patterns are flexible. Although not shown in the figures, it will be appreciated that FIGS. The stent shown in Figures 1-4 can bend in any direction and simultaneously in several directions.

In FIG. 4 shows FIG. 1 in an expanded form. As the stent expands, both vertical 11 and horizontal 12 meander patterns expand (i.e., all loops 14-20 open). As shown in FIG. 4, the expansion of the stent into the pattern results in two types of closed gaps: a large gap 42 between the meander patterns 12o and 12e and a small gap 44 between the meander patterns 12e and 12o. As can be seen, each large space 42 has two eyelets 14 on the left side and two eyelets 16 on the right side. The large spaces between the vertical meander patterns lle and llo in Fig. 42a have eyelets 18 on the top and bottom, while the gaps 18 in Fig. 42b

The large spaces between the meander patterns 10 and Ile have eyelets 20 on the top and bottom. The same applies to the small spaces 44a and 44b.

It should be noted that in FIG. 1 does not contract significantly during expansion due to the meander patterns 11 and 12. This is shown in detail in FIGS. 5A and 5B. In FIG. 5A is a vertical meander pattern 11, and FIG. 5B with changes in the horizontal meander pattern 12 as the stent expands. The initial patterns are represented by continuous, expansion-induced patterns with a dashed line.

In FIG. The vertical meander pattern 11 shown in Fig. 5A expands due to the expansion of the loops 14 and 16. As a result, the vertical meander pattern 11 lengthens by 2 hl per loop in the vertical direction, while shortening by 2-dl in the horizontal direction. Similarly, FIG. 5B, respectively, due to the expansion of the eyelets 18 and 20, respectively. As a result, the pattern lengthens in the horizontal direction by 2 d2 per eye, while shortening in the vertical direction by h2. Thus, the vertical elongation of the vertical meander pattern 11 at least partially compensates for the vertical shortening of the horizontal meander pattern 12 and vice versa. It should be noted that the ends of the stent are only partially compensated and may therefore contract somewhat.

The two rectangular, mutually compensating meander patterns 11 and 12 in FIG. 1 is extremely flexible. However, after expansion of the stent, changes in all of the loops 14 and 16 make the design of the stent considerably more rigid and allow the stent to maintain the desired internal diameter of the vessel.

The stent of the present invention may be made of sheet metal etched in FIG. 2. The etched metal is then wound into a tube 30.

Alternatively, FIG. 2 can also be made of welded or braided wire.

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The stent of the present invention can be made of metal and / or wire. The finished stent may be coated with a protective material, inserted into the medicament, and / or covered with a material that fills gaps 42 and 44, as needed.

The present invention encompasses all stents made using two rectangular or other angular meander patterns. Another possible variant with meander patterns at right angles is shown schematically in FIG. 6 and in rounded form in FIG. 7. FIG. 8 is a view similar to FIG. 7 meander patterns shown in expanded form. In FIGS. 6 and 7 are generally similar to FIG. 2 with the difference that there are more horizontal meander patterns 12 and they are of the same type, not right or left as in FIG. 2.

In FIGS. 6 and 7 show two types of vertical meander patterns 1 le and 1 lo rotated 180 degrees relative to each other (mirror image). The horizontal meander patterns 12 join each section 15 of the vertical meander pattern 11e.

FIG. 8 shows FIG. 7 in an expanded form. Because horizontal meander patterns are not divided into right and left ones, there are no large or small gaps in the extended pattern. All spaces in the extended pattern are the same size.

It will be appreciated by those skilled in the art that the present invention is not limited to the examples set forth above. The scope of the invention is defined by the following claims.