HK1001756B - A flexible expandable stent - Google Patents

Description

Flexible expandable implant stent

Technical FieldThe present invention relates generally to a stent for implantation in a living body.

Background

Various stents are known in the art. As used herein, a "stent" refers to a device made of a material compatible with the human body that is used to expand a blood vessel or other orifice of a cavity in the body and maintain the overall size of the lumen. Typically, the stent is delivered to the desired location in the body by an inflatable balloon, which, when inflated, expands, thereby expanding the orifice. Other mechanical means of expanding the stent may be used.

Representative patents in the field of stents made of wire include: U.S. patent 5019090 to Pinchuk; U.S. patent 5161547 to Tower; U.S. patent 4950227 to Savin et al; U.S. patent 5314472 to Fontaine; U.S. patents 4886062 and 4969458 to Wiktor; and U.S. patent 4856516 to Hi11 stead. Stents composed of cut metal are disclosed in the following patents: us patent 4733665 to Palmaz, us patent 4762128 to Rosenbluth, us patent 5102417 to Palmaz and Schatz, us patent 5195984 to Schatz and WO 91 FR 013820 to Meadox.

A stent described in U.S. patent 5102417 to Palmaz and Schatz has expandable tubular implants connected together by flexible connectors. The implant is formed by a plurality of grooves arranged parallel to the longitudinal axis of the tube. The flexible connector is a helical connector. Since such tubular implants are rigid, flexible connectors are required to allow the stent to bend as it passes through a curved vessel. When the stent of U.S. patent 5102417 is expanded, the tubular implant expands radially and eventually contracts longitudinally. But at the same time the screw connector will twist. Such twisting motion is highly likely to damage the blood vessel.

U.S. patent 5195984 to Schatz describes a similar stent but with a straight connector between the tubular implants parallel to the longitudinal axis of the tubular implants, which straight connector eliminates torsional movement but is not a strong connector.

Disclosure of Invention

Accordingly, it is an object of the present invention to provide a flexible stent which has minimal contraction in the longitudinal direction when expanded.

The technical solution of the above object is a stent formed of a tube having a pattern shape, the pattern shape in an expanded and deployed state comprising: a) odd first meander patterns and even first meander patterns having an axial direction extending in a first direction, and the odd first meander patterns being 180 ° out of phase with the even first meander patterns and the odd first meander patterns occurring between every two even first meander patterns; b) a second meander pattern having an axial direction extending in a second direction different from the first direction, wherein the second meander pattern intersects the odd first meander pattern and the even first meander pattern to form a substantially uniformly distributed structure; c) wherein the odd first meander patterns and the even first meander patterns are connected to the second meander patterns so as to leave a portion of the second meander patterns between each pair of the odd first meander patterns and the even first meander patterns; d) wherein the second meander patterns are connected to the odd and even first meander patterns so as to leave a loop of the odd and even first meander patterns between each pair of second meander patterns.

The stent of the present invention is formed of a tube having a pattern shape having first and second curved pattern shapes having axes extending in a first direction and in a second direction, wherein the second curved pattern shape is intertwined with the first curved pattern shape. The first and second directions may be orthogonal to each other.

According to an embodiment of the present invention, the first meander pattern shapes are formed as even and odd first meander pattern shapes. The even and odd first meander pattern structures are 180 ° out of phase with each other, and the odd pattern appears between every two even pattern shapes. The second meander pattern shape may be formed in even and odd pattern shapes.

Furthermore, according to a preferred embodiment of the present invention, the second meander pattern shape has two loops per period, and the even and odd first meander pattern shapes are connected to a first side and a second side of each loop of the second meander pattern shape, respectively.

The second meander patterns are formed by even and odd second meander patterns. In this embodiment, the even and odd first meander patterns have loops, and the even and odd second meander patterns are connected to the even and odd first meander patterns such that a complete loop remains between each pair of even and odd second meander patterns.

Also in accordance with a preferred embodiment of the present invention the first and second meander patterns are formed from a flat piece of metal. Alternatively, they may be cut from wire. In addition, they may be embedded or covered by any material compatible with the human body.

Drawings

The following detailed description is presented in order to provide a more complete understanding and appreciation of the invention when taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a patterned stent constructed and operative in accordance with a first preferred embodiment of the present invention;

FIG. 2 shows a pattern of the stent of FIG. 1;

FIG. 3 shows the stent of FIG. 1 in a bent state;

FIG. 4 shows the stent of FIG. 1 in an expanded form;

FIGS. 5A and 5B illustrate a change in the pattern of the stent of FIG. 1 due to expansion;

FIG. 6 is a schematic view of a second embodiment of a pattern for a stent;

FIG. 7 is a schematic view of a third embodiment of a pattern for a stent; and

fig. 8 is a schematic view of the pattern of fig. 7 in an extended state.

Detailed Description

Referring now to FIGS. 1-4, a first embodiment of a stent constructed and operative in accordance with the principles of the present invention is shown. FIG. 1 shows the stent in a non-expanded form, FIG. 2 shows the stent pattern, FIG. 3 shows the stent in a partially flexed position, and FIG. 4 shows the stent in an expanded form.

The stent of the present invention is a tube member whose side surface is formed in a plurality of two orthogonal bending patterns which are mutually crossed. The term "meander pattern" is used herein to describe a periodic pattern around a centerline; an "orthogonal meander pattern" is a pattern whose centerlines are orthogonal to each other.

In the stent of FIGS. 1-4, the two curved patterns are designated 11 and 12, which are most clearly seen in FIG. 2. The meander pattern 11 is a vertical sinusoid with a vertical centre line 9. Each period of the meander pattern 11 has two loops 14 and 16, of which loop 14 is open to the right and loop 16 is open to the left. Rings 14 and 16 share common members 15 and 17, member 15 being connected from one ring 14 to the next ring 16, and member 17 being connected from one ring 16 to the successive ring 14.

The meander pattern 12 is a horizontal pattern having a horizontal centerline 13, and the meander pattern 12 also has loops, indicated at 18 and 20, but between the two loops in each cycle is a straight extension 22, indicated at 22. Ring 18 opens downwardly and ring 20 opens upwardly. The vertical meander patterns 11 are in odd and even (o and e) patterns that are 180 ° out of phase with each other. Thus, each left open loop 16 of meander pattern 11o faces a right open loop 14 of meander pattern 11e, and right open loop 14 of meander pattern 11o faces a left open loop 16 of meander pattern 11 e.

The horizontal curved patterns 12 are also formed in odd and even numbers. The straight portion 22 of the horizontal bending pattern 12e intersects every third common member 17 of the vertical bending pattern 11 e. The straight portion 22 of the horizontal curved pattern 12o intersects every third common component 15 of the vertical curved pattern 11e starting from the two common components 15 following the intersecting common component 17. Finally, between the meander patterns 12e and 12o is a full loop 14 and between the meander patterns 12o and 12e is a full loop 16.

Returning to fig. 1, the pattern of fig. 2 is formed on a tube 30 of a deformable material (e.g., metal). Due to these two curved patterns, the stent of FIG. 1 becomes flexible when attached to a catheter balloon, thereby allowing easy navigation through curved vessels. An example of the stent bending in this manner in fig. 1 is shown in fig. 3.

In FIG. 3, the stent begins to bend at point A in the direction indicated by arrow 40. When the stent begins to buckle, the portion marked I becomes the inside of the buckle and the portion marked O becomes the outside of the buckle. The inside of the bent portion I is shorter than the outside of the bent portion O.

Upon bending, the loops 14-20 to the right of point A change shape to compensate for the difference in length between the inner and outer curved portions. For example, the loops 18i and 20i near the inner side of the curve are closer together than the loops 18o and 20o that extend over the outer side of the curve. The rings 14I and 16I near the curved inner side I are compressed, while the rings 14O and 16O near the curved outer side O are extended.

As shown in the figure, two bending patterns 11 and 12 are involved in the bending process. Although not shown in the drawings, it should be understood that the stent of FIGS. 1-4 may be bent in any direction and in more than one direction at any one time.

FIG. 4 illustrates the stent of FIG. 1 in a deployed form. When the stent is expanded, both of the meander patterns 11 and 12 are expanded (i.e., all loops 14-20 are open upward). As can be seen, the expanded stent has two types of encapsulated voids, namely a large void 42 between the meander patterns 12o and 12e and a small void 44 between the meander patterns 12e and 12 o. As shown, each large void 42 has two rings 14 on its left side and two rings 14 on its right side. The large gap between the vertical meander patterns lle and 11o, labeled 42a, has loops 18 at its top and bottom ends, and the large gap between the vertical meander patterns 11o and 11e, labeled 42b, has loops 20 at its top and bottom ends. The same is true for the small gaps 44a and 44 b.

It should be noted that the stent of FIG. 1 does not undergo significant contraction during expansion due to the orthogonal bending patterns 11 and 12. For this, reference may be made to the details shown in fig. 5A and 5B. Fig. 5A shows the movement of a vertical bending pattern 11 during stretching, and fig. 5B shows the movement of a horizontal bending pattern 12 during stretching. The original pattern is shown in solid lines and the expanded pattern in dashed lines.

The vertical meander pattern 11 of fig. 5A is stretched by widening its loops 14 and 16. The result is that each loop of the vertical meander pattern 11 is bent by 2h₁The amount of (c) increases vertically. However, it is also 2d₁The amount of (2) shrinks horizontally. Similarly, the horizontal meander pattern of fig. 5B is stretched by widening its loops 18 and 20. The result is that each loop of the horizontally meandering pattern 12 is bent by 2d₂The amount of (c) increases horizontally. However, this will also be in h₂The amount of (c) shrinks vertically. Thus, vertical growth of the vertical meander pattern 11 at least partially compensates for vertical shrinkage of the horizontal meander pattern 12, and vice versa. It should be noted that the ends R of any stent are partially offset and therefore will shrink slightly.

It should be appreciated that the two orthogonal bending patterns 11 and 12 and their compensation provided to each other enable the unexpanded stent of FIG. 1 to be flexible. However, as the stent is deployed, the variation in each of the rings 14 and 16 results in a rigid final stent, thereby maintaining the desired inner diameter of the vessel.

The stent of the present invention may be fabricated by corroding a flat metal in the pattern of FIG. 2. The corroded metal is then bent into a tube 30. Alternatively, the pattern of fig. 2 may be formed by welding or twisting wires.

It should be understood that the stent of the present invention can be made of metal and/or wire. In addition, it may be coated with a protective material, imbedded with a drug and/or coated with a material that fills voids 42 and 44.

It should be understood that the present invention encompasses all stents made from a pattern of two orthogonal or non-orthogonal curved patterns. The present invention also provides another exemplary pattern that is also formed from an orthogonal meander pattern, wherein fig. 6 is a schematic view and fig. 7 is a schematic view of a more circular head. Fig. 8 is a schematic view of the pattern of fig. 7 in an expanded state. The pattern of fig. 6 and 7 is similar to that shown in fig. 2, except that it has more horizontal meander patterns 12, and they are of the same type, rather than odd-even as in fig. 2.

As shown in fig. 6 and 7, there are two types of the vertical bending patterns 11e and 11o which are shifted in phase by 180 ° from each other. The horizontal curved pattern 12 is connected to each line 15 of the vertical curved pattern 11 e.

Fig. 8 illustrates the pattern of fig. 7 in an expanded state, and since there are no odd and even horizontal meander patterns, there are large and small voids in the expanded state of fig. 8. All voids are the same size.

It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather, the scope of the invention is defined by the appended claims.

Claims (9)

1. A stent formed from a tube having a pattern shape, the pattern shape in an expanded and deployed state comprising:

a) odd first meander patterns (11o) and even first meander patterns (11e) having an axial direction (9) extending in a first direction, and the odd first meander patterns (11o) being 180 ° out of phase with the even first meander patterns (11e) and the odd first meander patterns occurring between every two even first meander patterns;

b) a second meander pattern (12) having an axial direction (13) extending in a second direction different from said first direction, wherein said second meander pattern (12) is interleaved with said odd first meander pattern (11o) and said even first meander pattern (11e) to form a substantially uniformly distributed structure;

c) wherein said odd first meander patterns (11o) and even first meander patterns (11e) are connected to said second meander patterns (12) so as to leave a portion of the second meander patterns (12) between each pair of odd first meander patterns (11o) and even first meander patterns (11 e);

d) wherein the second meander patterns (12) are connected to the odd first meander patterns (11o) and the even first meander patterns (11e) so as to leave a loop of the odd first meander patterns (11o) and the even first meander patterns (11e) between each pair of second meander patterns (12).

2. A stent according to claim 1 wherein the second pattern of bends has two loops (18, 20) per cycle, and wherein odd and even first patterns of bends are connected on the first and second sides of each loop, respectively.

3. The stent according to claim 1 or 2, wherein the odd-numbered first meander patterns (11o) and the even-numbered first meander patterns (11e) have loops, and the second meander patterns (12) are connected to the odd-numbered first meander patterns (11e) and the even-numbered first meander patterns (11o) so as to leave two loops (14, 16) of the odd-numbered first meander patterns (11o) and the even-numbered first meander patterns (11e) between each pair of second meander patterns (12).

4. The stent according to claim 1 or 2, wherein said odd first curved patterns (11o) and even first curved patterns (11e) have loops, and said second curved patterns (12) are formed by odd and even second curved patterns (12o, 12e), wherein said odd and even second curved patterns are connected to said odd first curved patterns (11e) and even first curved patterns (11o) so as to leave three loops (14, 16, 14; 16, 14, 16) of said odd first curved patterns (11o) and even first curved patterns (11e) between each pair of said odd and even second curved patterns (12o, 12 e).

5. A stent according to claim 1 or 2, wherein the first and second directions (9, 13) are orthogonal.

6. A stent according to claim 1 or 2, wherein the first and second directions (9, 13) are non-orthogonal.

7. A stent according to claim 1 or 2, wherein the first and second meander patterns (11, 12) are formed of wire.

8. A stent according to claim 1 or 2, wherein the first and second curved patterns (11, 12) are cut from a flat metal material.

9. A stent according to claim 1 or 2, wherein the stent is coated with a protective material or embedded with a drug or covered with a material.