STENT PROSTHESIS

Abstract

A stent for use in hollow tubular organs, comprising a continuous tubular or cylindrical inner cavity which is delimited by a wall. The wall is formed in a tubular or cylindrical manner about an axis which runs in a longitudinal direction and has a structure which surrounds the wall. The structure is made of elements, and the elements are made of loops which are arranged about the longitudinal axis in the radial direction. The elements are rigidly connected via connection points such that a tubular or cylindrical single-piece wall structure is produced, and the stent has acute angles in the region of the connection points.

Claims

1. A stent with a continuous, interior, tubular or cylindrical cavity bounded by a wall, wherein the wall is configured to be tubular or cylindrical and extending about an axis running in the longitudinal direction (x) and comprises a structure running about the wall, wherein the structure is formed from elements and the elements are formed from loops, which are arranged substantially in the radial direction (y) about the longitudinal axis, and they have loop peaks and loop valleys arranged in alternating manner and running substantially parallel to the longitudinal direction (x), so that an element is firmly connected to the preceding or following element by connection points in the region of the loop valleys of the elements and the loop peaks of the following elements and in the region of the loop peaks of the elements and the loop valleys of the preceding elements in order to produce a one-piece tubular or cylindrical wall structure, characterized in that the loop peaks and the opposite loop valleys in the longitudinal direction stand in direct contact or overlap each other and each time at the connection points a web S.sub.1 running substantially parallel to the longitudinal direction (x) and a web S.sub.3 running substantially parallel to the radial direction (y) is formed, while S.sub.1 has at least the width of a web S.sub.2 in the region of the loop line between the loop peaks and the loop valleys and acute angles (φ) are present in the region of the connection points between loop valleys and loop peaks.

2. The stent according to claim 1, wherein the acute angles (φ) have their starting points on the loop line in the region between the loop peak and the loop valley and the angles (φ) take on a smaller angular dimension under increasing continual expansion of the stent.

3. The stent according to claim 1, wherein the stent is made from a single tubular piece of material.

4. The stent according to claim 1, wherein the stent is formed from a metal, an alloy, a plastic, a shape memory material, Nitinol, or a combination of these materials.

5. The stent according to claim 1, wherein the loops are formed meandering, Ω-shaped or U-shaped.

6. The stent according to claim 1, wherein the loops have a loop line which is partly or entirely jagged, wavy, formed from individual straight segments, or smooth.

7. The stent according to claim 1, wherein the web S.sub.1 has a shorter length than the web S.sub.3, S.sub.1 being the same length, at most ¾, at most ⅔, at most ½, at most ⅓ or at most ¼ the length of S.sub.3.

8. The stent according to claim 1, wherein the stent is radiologically opaque or at least has a radiologically opaque marking.

9. The stent according to claim 1, wherein the stent comprises coupling elements at the longitudinal, axial ends, by which several stents are joined together reversibly directly or indirectly by spacers.

10. The stent according to claim 1, wherein the stent is electroplated, electropolished and/or mechanically polished at least on one of the surfaces and/or at least at one of the longitudinal, axial ends.

11. The stent according to claim 1, wherein the elements have a maximum in the region of the loop peaks and a minimum in the region of the peak valleys, where the loops have a length λ in the radial direction (y) from maximum to maximum of the same element and where the loop minimum lies at λ/2 or an odd multiple thereof.

12. The stent according to claim 1, wherein the elements are formed from at least 3 loops each with 3 loop peaks and valleys.

13. The stent according to claim 1, wherein in the inner region of the loop peaks or valleys of an element the loop peaks or valleys have an extension b or b′, respectively, and the loops in the region between neighboring loop peaks or valleys of an element have an extension a or a′, respectively, where a or a′ is at most equal to the extension b or b′, a or a′ is larger than 0 and smaller than b or b′, or a or a′ is equal to 0, but the neighboring loop peaks or valleys of an element are not firmly connected here.

14. The stent according to claim 1, wherein each time two neighboring elements form an element pair and have a length L in the longitudinal direction (x), where the length L corresponds at most to 100%, 75%, 50% or at least to 21% of the internal diameter of the element pair in the non-expanded condition of the stent.

15. The stent according to claim 13, wherein the length L of an element pair each time successively decreases or successively increases in relation to the neighboring element pairs in the longitudinal direction (x).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The invention shall be described more closely below with the aid of sample embodiments in drawings. The explanations are meant solely as examples and do not limit the general notion of the invention.

[0049] There are shown:

[0050] FIG. 1 a schematic representation of a stent according to the prior art with a rigid design, so-called Closed Cell Design;

[0051] FIG. 2 in a schematic representation of a stent according to the prior art with a partly flexible design, so-called Open Cell Design;

[0052] FIG. 3 in a schematic representation an embodiment of the stent according to the invention;

[0053] FIG. 4 in a schematic representation a feature of an embodiment of the stent according to the invention;

[0054] FIGS. 5a to 5c each time in a schematic representation a feature of an embodiment of the stent according to the invention in different states of extension b, b′, a and a′;

[0055] FIG. 6 in a schematic 3D representation a feature of an embodiment of the stent according to the invention;

[0056] FIG. 7 each time in a schematic representations a feature as well as a detail of the angle φ of an embodiment of the stent according to the invention in different states B, C, D, and E of the extension of the stent.

DETAILED DESCRIPTION OF THE INVENTION

[0057] FIG. 1 shows a stent according to the prior art in the so-called rigid or Closed Cell Design. Several elements 300, 310 are arranged in succession in the longitudinal direction x. An element 300 is connected continuously for the entire length in the radial direction y by means of connectors 220 to the following element 310.

[0058] FIG. 2 likewise shows a stent according to the prior art, having in part a flexible, so-called Open Cell Design. In this design, an element 300 is connected in the radial direction y by connectors 220 to a neighboring element 310 in the longitudinal direction x. However, there is no continuous connection here in the radial direction y, but instead there are regions in which no connection is present between the elements 300 and 310.

[0059] FIG. 3 shows an embodiment of the stent according to the invention, where an element 300 is firmly connected to preceding elements 320 and following elements 310 in the longitudinal direction x by connection points 200. The elements 300, 310, 320 have the shape of loops in the radial direction y with loop peaks and loop valleys.

[0060] FIG. 4 shows a schematic detail feature of one embodiment of the stent according to the invention, where an element 300 and its neighboring element 310 following in the longitudinal direction x are represented. The element 300 here has loops with loop peaks 400 and loop valleys 500. The element 300 has a loop length λ from one loop peak to a neighboring loop peak in the radial direction y, while each time the loop valley lies at λ/2. Moreover, the element 300 has a length L/2 from the loop peaks to the loop valleys in the longitudinal direction x. The element pair 300, 310 has a length L in the longitudinal direction x. The element 300 is shifted relative to the following element 310 by a half loop length λ/2, so that its loop valleys are firmly connected to the loop peaks of the following element 310 by connection points 200. Moreover, in the region of the loop peaks and valleys of the element 300 there is represented an extension b or b′ with a center point m or m′, respectively. The center point m or m′ of the extension b or b′ in this embodiment lies on the normals N or N′ running orthogonally to the tangent of the maximum or minimum of the loop peak or valley.

[0061] FIG. 5a shows an embodiment of the stent according to the invention in a state in which the extension a or a′ is greater than 0, but smaller than b or b′. By state is meant here a non-expanded state, in which the stent extends even further, i.e., its diameter can further increase outwardly in the radial direction. Moreover, there are shown a web S.sub.1, which runs parallel to the longitudinal direction x, and a web S.sub.3, which runs parallel to the radial direction y. Moreover, a web S.sub.2 is shown, which corresponds to the width of the loop line in the region between the loop peak and the loop valley. It is the case here that S.sub.1 has at least the width of S.sub.2, and that the web S.sub.1 has a shorter length than the web S.sub.3. Moreover, the stent has acute angles φ in the region of the connection points between loop valleys and loop peaks, which take on a smaller angular dimension upon expansion of the stent. However, the stent has no so-called connectors, so that no spacings (connectors) are present at the connection points between loop valleys and loop peaks. Instead, the loop valleys and the loop peaks overlap at the connection points according to the invention.

[0062] FIG. 5b shows an embodiment of the stent according to the invention in a state in which the extension a or a′ is equal to that of b or b′. By state is meant here a non-expanded state, in which the stent extends even further, i.e., its diameter can further increase outwardly in the radial direction.

[0063] FIG. 5c shows an embodiment of the stent according to the invention in a state in which the extension a or a′ is equal to 0 and b or b′ is greater than 0. But the neighboring loop peaks and valleys here are not firmly interconnected in the region of a or a′ of an element, i.e., upon an expansion of the stent a or a′ can again become larger than 0. By state is meant here a non-expanded state, in which the stent extends even further, i.e., its diameter can further increase outwardly in the radial direction.

[0064] FIG. 6 shows a detail feature of an embodiment of the stent according to the invention in a schematic 3D representation.

[0065] FIG. 7 shows an embodiment of the stent according to the invention in different extension states. The states here range from B, little extended if at all, to C and D, and then to E, very broadly extended, the extension states standing in a relation of E>D>C>B. The acute angle φ, here represented as B1 to E1 depending on the extension state, decreases upon extension from B to E in the relation B1>C1>D1>E1. E1 at maximum extension can take on a value of E1>=0. The angle which has its starting points on the loop line in the region between the loop peak and the loop valley and which is denoted as B0 to E0 also diminishes upon extension from B to E in the relation B0>C0>D0>E0. Thus, the stent can either be given more flexibility and a larger radial force, as would be the case in state E, or less flexibility with lesser radial force, as would be the case for example in state C. However, the design or the structure of the stent does not need to be changed for this.

LIST OF REFERENCES

[0066] 200 Connection point [0067] 210 Non-connected point [0068] 220 Connector [0069] 300 Element [0070] 310 Following element [0071] 320 Preceding element [0072] 400 Region of the loop peak [0073] 500 Region of the loop valley [0074] λ Loop length [0075] λ/2 Half loop length [0076] φ Acute angle [0077] B1 Acute angle φ in extension state B [0078] C1 Acute angle φ in extension state C [0079] D1 Acute angle φ in extension state D [0080] E1 Acute angle φ in extension state E [0081] B0 Angle in extension state B [0082] C0 Angle in extension state C [0083] D0 Angle in extension state D [0084] E0 Angle in extension state E [0085] B Extension state of the stent [0086] C Extension state of the stent [0087] D Extension state of the stent [0088] E Extension state of the stent [0089] a Extension in the region between neighboring loop peaks of an element [0090] a′ Extension in the region between neighboring loop valleys of an element [0091] b Extension in the region of a loop peak [0092] b′ Extension in the region of a loop valley [0093] L Length of an element pair in longitudinal direction [0094] L/2 Length of an element in longitudinal direction [0095] m Center point of extension b [0096] m′ Center point of extension b′ [0097] N Normal orthogonal to the tangent of a loop minimum [0098] N′ Normal orthogonal to the tangent of a loop minimum [0099] S.sub.1 Web in the region of the connection point running substantially parallel to the longitudinal direction [0100] S.sub.2 Web in the region of the loop line between the loop peak and the loop valley [0101] S.sub.3 Web in the region of the connection point running substantially parallel to the radial direction [0102] x Longitudinal direction [0103] y Radial direction