AU779582B2 - A stent - Google Patents

Description

r S Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant: Actual Inventor: Address for Service: MEDINOL LTD., of Kiryat Atidim, P.O. Box 58165, 61581 Tel Aviv, Israel ISRAEL, Henry M.

PINCHASIK, Gregory DAVIES COLLISON CAVE, Patent Attorneys, of 1 Little Collins Street, Melbourne, Victoria 3000, Australia Invention Title: A Stent The following statement is a full description of this invention, including the best method of performing it known to us: 1 Q \OPER\GCPU I246div doc 26r/21? 2 A STENT FIELD OF THE INVENTION The present invention relates generally to stents for implanting into a living body.

BACKGROUND OF THE INVENTION Various stents are known in the art wherein, for the present application, the term "stent" indicates a device, made of body-compatible material, which is utilized to widen a blood vessel, or other orifice in 15 the body, and to maintain the resultant size of the lumen. Typically, the stent is delivered to the Sdesired location in the body with an inflatable balloon and, when the balloon is inflated, the stent expands, thereby widening the orifice. Other mechanical devices 20 which cause expansion of the stent are also utilized.

Exemplary patents in the field of stents formed of wire are: U.S. 5,019,090 to Pinchuk, U.S. 5,161,547 to Tower, U.S. 4,950,227 to Savin, et al., U.S. 5,314,472 to Fontaine, U.S. 4,886,062 and U.S. 4,969,458 to Wiktor and U.S. 4,856,516 to Hillstead. Stents formed of cut stock metal are described in: U.S. 4,733,665 to :i Palmaz, U.S. 4,762,128 to Rosenbluth, U.S. 5,102,417 to Palmaz and Schatz, U.S. 5,195,984 to Schatz and WO 91 FR013820 to Meadox.

The stents described in U.S. 5,102,417 to Palmaz and Schatz have expandable tubular grafts connected together with a flexible connector. The grafts are formed of a plurality of slots disposed parallel to the longitudinal axis of the tube. The flexible connectors are helical connectors. Since the tubular grafts are relatively rigid, the flexible connectors are needed so that the stents can bend when being fed through a curved blood vessel. When the stents of U.S. 5,102,417 P.PERGCP I1246di, qsdoc- 1711104 -3expand, the grafts expand radially and, consequently, shrink longitudinally. However, at the same time, the helical connectors twist. The twisting motion is most probably harmful to the blood vessel.

U.S. 5,195,984 to Schatz describes a similar stent but with one straight connector, parallel to the longitudinal axis of the tubular grafts, between tubular grafts. The straight member removes the twisting motion; however, it is not a very strong connector.

SUMMARY OF THE PRESENT INVENTION An object of the present invention is to provide a stent formed of a tube having a patterned shape, the patterned shape comprising: 1: 5 first meander patterns which are periodic about axes ooooo S"extending in a first direction; second meander patterns which are periodic about axes extending in a second direction perpendicular to said first eeeee direction, wherein said second meander patterns are intertwined with said first meander patterns to form a generally uniform distributed structure, wherein said second meander patterns define a plurality of flexible arcuate compensating members adapted to elongate in said second direction to compensate for the tendency of said first meander patterns to foreshorten when said stent is expanded.

The invention also provides an expandable stent in the shape of an elongated unitary tube formed from flat metal having a flexible patterned shape suitable for insertion into a blood vessel or other orifice in the body in which it may be expanded to maintain the resultant size of the lumen comprising: a plurality of first meander patterns extending in a QiocpI\s714c dc-097M4 -4first direction and a plurality of second meander patterns extending in a second direction, said meander patterns being connected together to form a plurality of flexible cells so that when attached to a balloon catheter the stent easily passes through the curved blood vessels, each of said flexible cells being provided with a plurality of loops adapted to cooperate so that upon the expansion of said stent the growth of some of said loops in the longitudinal direction of the tube compensates for the shrinkage of other loops in the longitudinal direction of the tube to eliminate any significant shrinkage of the stent in length during expansion.

The invention also provides a flexible, expandable stent, comprising: 15 a plurality of first meander patterns extending in a first direction and a plurality of second meander patterns extending in a second direction intersecting said first meander patterns to define a plurality of enclosed cells, said first and said second meander patterns disposed and i 20 adapted to cooperate so that upon the expansion of said stent the vertical growth of said first meander patterns substantially compensates for the vertical shrinkage of said :second meander patterns.

25 The invention also provides a flexible, expandable stent, comprising: a plurality of first meander patterns extending in a first direction and a plurality of second meander patterns extending in a second direction intersecting said first meander patterns to define a plurality of enclosed cells, said first and said second meander patterns disposed and adapted to cooperate so that upon the expansion of said Q,"vp4.I 4C doc-09M4 stent said first meander patterns and said second meander patterns change shape to compensate for the tendency of said stent to foreshorten when said stent is expanded.

The invention also provides a flexible, expandable stent having a longitudinal axis, comprising: a plurality of first meander patterns extending in a first direction and a plurality of second meander patterns extending in a second direction intersecting said first meander patterns to define a plurality of enclosed cells, said meander patterns adapted so that said stent prior to expansion is substantially uniformly flexible along its longitudinal axis and bendable in substantially any direction and in several directions at once without 15 affecting the structural or functional integrity of said stent, said first and said second meander patterns disposed and adapted to cooperate so that upon the expansion of said stent the vertical growth of said first meander patterns substantially compensates for the vertical shrinkage of said 20 second meander patterns, said meander patterns further adapted to impart rigidity to said stent in an amount sufficient to support a lumen when said stent is expanded.

The invention also provides a flexible, expandable stent having a longitudinal axis, comprising: a plurality of flexible cells provided with a plurality of first loops and a plurality of second loops, said loops adapted so that said stent prior to expansion is substantially uniformly flexible along its longitudinal axis and bendable in substantially any direction and in several directions at once without affecting the structural or functional integrity of said stent, said first loops and Q:oMpeIpi8714c d=c09M74 -6said second loops disposed and adapted to cooperate so that upon the expansion of said stent said first loops and said second loops change shape to compensate for the tendency of said stent to foreshorten when said stent is expanded, said loops further adapted to impart rigidity to said stent in an amount sufficient to support a lumen when said stent is expanded.

The invention also provides a flexible, expandable stent having a longitudinal axis, comprising: a plurality of first meander patterns extending in a first direction and a plurality of second meander patterns extending in a second direction intersecting said first meander patterns to define a plurality of enclosed cells, 15 said meander patterns adapted so that said stent prior to expansion is substantially uniformly flexible along its longitudinal axis and bendable in substantially any direction and in several directions at once without affecting the structural or functional integrity of said 20 stent, said first and said second meander patterns disposed and adapted to cooperate so that upon the expansion of said stent said first meander patterns and said second meander patterns change shape to compensate for the tendency of said stent to foreshorten when said stent is expanded, said 25 meander patterns further adapted to impart rigidity to said stent in an amount sufficient to support a lumen when said stent is expanded.

The invention also provides a flexible, expandable stent comprising: an elongated unitary tube formed of a pattern which defines spaces or cells cut from flat metal, said spaces or Q.%OPERGCPV y 204I1 7\l 14c.doc17/1 104 -7cells adapted to cooperatively change shape when the stent is bent, each of said spaces or cells being adapted to facilitate either longitudinal expansion or shrinkage in order to accommodate the stent's bending.

The invention also provides a flexible, expandable stent, comprising: a plurality of flexible cells provided with a plurality of first loops and a plurality of second loops, said first loops and said second loops disposed and adapted to cooperate so that upon the expansion of said stent the vertical growth of said first loops substantially compensates for the vertical shrinkage of said second loops.

15 The invention also provides a flexible, expandable stent, comprising: a plurality of flexible cells provided with a plurality of first loops and a plurality of second loops, said first loops and said second loops disposed and adapted to cooperate so that upon the expansion of said stent said first loops and said second loops change shape to compensate for the tendency of said stent to foreshorten when said stent is expanded.

o 25 The invention also provides a flexible, expandable stent having a longitudinal axis, comprising: a plurality of flexible cells provided with a plurality of first loops and a plurality of second loops, said loops adapted so that said stent prior to expansion is substantially uniformly flexible along its longitudinal axis and bendable in substantially any direction and in several directions at once without affecting the structural or Q 3pa I814 c.dc-0907)D -8functional integrity of said stent, said first loops and said second loops disposed and adapted to cooperate so that upon the expansion of said stent the vertical growth of said first loops substantially compensates for the vertical shrinkage of said second loops, said loops further adapted to impart rigidity to said stent in an amount sufficient to support a lumen when said stent is expanded.

S: (The next page is page 11) P:OPER\GCP31 24I6d spedoc-25nA)2A2 -11- BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: Fig. 1 is an illustration of a patterned stent, constructed and operative in accordance with a first preferred embodiment of the present invention; Fig. 2 is an illustration of the pattern of the stent of Fig. 1; Fig. 3 is an illustration of the stent of Fig. 1 in a bent position; Fig. 4 is an illustration of the stent of Fig. 1 in an expanded format; Figs. 5A and 5B are illustrations of the changes in the 1" 5 patterns of the stent of Fig. 1 due to expansion; Fig. 6 is a schematic illustration of a second embodiment of the pattern for a stent; Fig. 7 is an illustration of a third embodiment of the pattern for the stent; and 12- Fig. 8 is an illustration of the pattern of Fig. 7 in an expanded format.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Reference is now made to Figs. 1 4 which illustrate a first embodiment of a stent, constructed and operative in accordance with the principles of the present invention. Fig. 1 illustrates the stent in its non-expanded form, Fig. 2 illustrates the pattern of the stent, Fig. 3 illustrates it in a partially bent position and Fig. 4 illustrates it in an expanded form.

~The stent of the present invention is a tube whose foo sides are formed into a plurality of each of two orthogonal meander patterns which patterns are 15 intertwined with each other. The term "meander pattern" is taken herein to describe a periodic pattern about a center line and "orthogonal meander patterns" are patterns whose center lines are orthogonal to each Sother.

In the stent of Figs. 1 4, the two meander patterns are labeled 11 and 12 and they are most easily seen in Fig. 2. Meander pattern 11 is a vertical sinusoid having a vertical center line 9. Meander .:"pattern 11 has two loops 14 and 16 per period wherein S" 25 loops 14 open to the right while loops 16 open to the left. Loops 14 and 16 share common members 15 and 17, where member 15 connects from one loop 14 to its following loop 16 and member 15 connects from one loop 16 to its following loop 14.

Meander pattern 12 is an horizontal pattern having an horizontal center line 13. Meander pattern 12 also has loops, labeled 18 and 20, but between loops of a period is an extended straight section labeled 22.

Loops 18 open downwards and loops 20 open upwards.

Vertical meander pattern 11 is provided in odd and even (o and e) versions which are 1800 out of phase with 13each other. Thus, each left opening loop 16 of meander pattern Iio faces a right opening loop 14 of meander pattern lie and a right opening loop 14 of meander pattern 110o faces a left opening loop 16 of meander pattern lie.

Horizontal meander pattern 12 is also provided in odd and even forms. The straight sections 22 of horizontal meander pattern 12e intersect with every third common member 17 of vertical meander pattern lie.

The straight sections 22 of horizontal meander pattern 120 intersect with every third common member 15 of vertical meander pattern le. beginning with the common member 15 two after an intersected common member 17.

*The result is a full loop 14 between meander patterns 12e and 120 and a full loop 16 between meander patterns 120 and 12e.

Returning to Fig. 1, the pattern of Fig. 2 is formed into a tube 30 of an easily deformable material,

*SS*

such as a metal. Due to the two meander patterns, the 20 stent of Fig. 1, when attached over a catheter balloon, is flexible and can therefore be easily dragged through curved blood vessels. An example of the way in which the stent of Fig. 1 bends is illustrated in Fig. 3.

In Fig. 3, the stent begins to bend at the point marked A in the direction marked by arrow 40. As the stent begins to curve, the section marked I becomes the inside of the curve while the section marked 0 becomes the outside of the curve. The inside of the curve I is shortened vis-a-vis the outside of the curve O.

During bending, the loops 14 20 to the right of the point A change shape in order to compensate for the differences in length between the inside and outside curves. For example, loops 18i and 20i near the inside of the curve are closer together than loops 180 and 200 on the outside of the curve, which expand. Loops 14i and 16i near the inside I are compressed while the 14 loops 140 and 160 closer to the outside O of the curve are expanded.

As can be seen, both meander patterns 11 and 12 are involved in the bending. Although not shown, it will be appreciated that tne stent of Figs. 1 4 can bend in any direction and in more than one direction at any time.

Fig. 4 illustrates the stent of Fig. 1 in its expanded form. When the stent expands, both meander patterns 11 and 12 expand all loops 14 20 open up). As can be seen, the expanded stent has two types of enclosed spaces, a large space 42 between meander patterns 120 and 12e and a small space 44 between meander patterns 12e and 120. As can also be seen, 15 each large space 42 has two loops 14 on its left side o and two loops 16 on its right side. The large spaces between vertical meander patterns lle and iio, which are labeled 42a, have loops 18 at their tops and Ce e.mS bottoms while the large spaces between vertical meander patterns ilo and lie, whicn are labeled 42b, have loops 20 at their tops and bottoms. Similarly for small spaces 44a and 44b.

It is noted that, due to the orthogonal meander patterns 11 and 12, the stent of Fig. 1 does not 25 significantly shrink during expansion. This is illustrated in detail in Figs. 5A and 5B to which reference is now made. Fig. 5A illustrates the movement, during expansion, of one vertical meander pattern 11 and Fig. 5B illustrates the movement, during expansion, of one horizontal meander pattern 12. The original patterns are shown with solid lines and the expanded patterns are shown with dashed lines.

The vertical meander pattern 11 of Fig. 5A expands by widening its loops 14 and 16. As a result, the vertical meander pattern 11 grows vertically by an amount per loop. However, it also shrinks horizontally, by an amount Similarly, the horizontal meander pattern 12 of Fig. 5B expands by widening its loops 18 and 20. As a result, the horizontal meander pattern 12 grows horizontally by an amount 2*d 2 per loop. However, it also shrinks vertically, by an amount h 2 Thus, the vertical growth of the vertical meander pattern 11 compensates, at least partially, for the vertical shrinkage of the horizontal meander pattern 12, and vice versa. It is noted that the end portions of any stent are only partially compensated and therefore, may shrink somewhat.

It will be appreciated that the two orthogonal meander patterns 11 and 12 and the compensation they 15 provide to each other provides flexibility to the unexpanded stent of Fig. 1. However, when the stent is expanded, the changes in each of loops 14 and 16 provide rigidity to the resultant stent and thus, enable the stent to maintain a blood vessel at a 20 desired inner diameter.

The stent of the present invention can be manufactured from flat metal which is etched into the pattern of Fig. 2. The etched metal is then bent to form the tube 30. Alternatively, the pattern of Fig. 2 can be manufactured from welded or twisted wire.

It will be appreciated that the stent of the present invention can be made from metal and/or wire.

Additionally, it can be plated with a protective material, embedded with a medicine, and/or covered with a material which can fill in the spaces 42 and 44.

It will be appreciated that the present invention encompasses all stents manufactured with a pattern formed of two meander patterns, orthogonal or otherwise. Another exemplary pattern, also with orthogonal meander patterns, is provided herein wherein Fig. 6 is a schematic version and Fig. 7 is a more P.OPERIGCPO 0124ds sp- doc-15M3DU 16rounded version. Fig. 8 shows the pattern of Fig. 7 in an expanded format. The pattern of Figs. 6 and 7 is similar to that shown in Fig. 2 except that it has more horizontal meander patterns 12 and they are of one kind, rather than being even and odd as in Fig. 2.

As can be seen in both Figs. 6 and 7, there are two types of vertical meander patterns lie and Iio which are 180' out of phase with each other. The horizontal meander patterns 12 connect with every line 15 of vertical meander pattern lie.

Fig. 8 illustrates the pattern of Fig. 7 in an expanded format. Since there are no even and odd horizontal meander patterns, in the expanded format of Fig. 8, there are no large and small spaces. Instead, all spaces are of the same size.

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

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that that prior art forms part of the common general knowledge in Australia.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (1)

18- any significant shrinkage of the stent in length during expansion. 3. A stent according to claim 2 wherein changes in the shape of the loops provide rigidity to the stent upon expansion to enable the stent to maintain a blood vessel or lumen at a desired inner diameter. 4. A stent according to claim 3 wherein the flexible cells of said stent are formed from orthogonal intertwined first and second meander patterns. A stent according to claim 2 wherein the flexible cells of said stent are formed from intertwined circumferential 15 and longitudinal meander patterns, and wherein upon expansion the circumferential growth of the circumferential meander pattern compensates, at least partially, for the circumferential shrinkage of the longitudinal meander pattern and vice versa. 6. A stent according to claim 5 wherein the end portions of said stent shrink somewhat upon expansion. 7. A flexible, expandable stent, comprising: 25 a plurality of first meander patterns extending in a first direction and a plurality of second meander patterns extending in a second direction intersecting said first meander patterns to define a plurality of enclosed cells, said first and said second meander patterns disposed and adapted to cooperate so that upon the expansion of said stent the vertical growth of said first meander patterns substantially compensates for the vertical shrinkage of said Q) 1 97cp pl87 -d09)D7,4 -19- second meander patterns. 8. A flexible, expandable stent, comprising: a plurality of first meander patterns extending in a first direction and a plurality of second meander patterns extending in a second direction intersecting said first meander patterns to define a plurality of enclosed cells, said first and said second meander patterns disposed and adapted to cooperate so that upon the expansion of said stent said first meander patterns and said second meander patterns change shape to compensate for the tendency of said stent to foreshorten when said stent is expanded. 9. A flexible, expandable stent having a longitudinal 15 axis, comprising: a plurality of first meander patterns extending in a first direction and a plurality of second meander patterns extending in a second direction intersecting said first meander patterns to define a plurality of enclosed cells, 20 said meander patterns adapted so that said stent prior to expansion is substantially uniformly flexible along its longitudinal axis and bendable in substantially any direction and in several directions at once without affecting the structural or functional integrity of said e 25 stent, said first and said second meander patterns disposed and adapted to cooperate so that upon the expansion of said stent the vertical growth of said first meander patterns substantially compensates for the vertical shrinkage of said second meander patterns, said meander patterns further adapted to impart rigidity to said stent in an amount sufficient to support a lumen when said stent is expanded. Q:Icqe6 \I 8"14 Lt..dOC0o10 A flexible, expandable stent having a longitudinal axis, comprising: a plurality of flexible cells provided with a plurality of first loops and a plurality of second loops, said loops adapted so that said stent prior to expansion is substantially uniformly flexible along its longitudinal axis and bendable in substantially any direction and in several directions at once without affecting the structural or functional integrity of said stent, said first loops and said second loops disposed and adapted to cooperate so that upon the expansion of said stent said first loops and said second loops change shape to compensate for the tendency of said stent to foreshorten when said stent is expanded, said loops further adapted to impart rigidity to said stent in an 0*e* 15 amount sufficient to support a lumen when said stent is expanded. 11. A flexible, expandable stent having a longitudinal axis, comprising: 20 a plurality of first meander patterns extending in a *0P* first direction and a plurality of second meander patterns V.. extending in a second direction intersecting said first 0-00 meander patterns to define a plurality of enclosed cells, said meander patterns adapted so that said stent prior to 25 expansion is substantially uniformly flexible along its longitudinal axis and bendable in substantially any direction and in several directions at once without affecting the structural or functional integrity of said stent, said first and said second meander patterns disposed and adapted to cooperate so that upon the expansion of said stent said first meander patterns and said second meander patterns change shape to compensate for the tendency of said Q.OPERGCVCP~iuY ZO4NS74dc-17/1 I 4 -21- stent to foreshorten when said stent is expanded, said meander patterns further adapted to impart rigidity to said stent in an amount sufficient to support a lumen when said stent is expanded. 12. A flexible, expandable stent comprising: an elongated unitary tube formed of a pattern which defines spaces or cells cut from flat metal, said spaces or cells adapted to cooperatively change shape when the stent is bent, each of said spaces or cells being adapted to facilitate either longitudinal expansion or shrinkage in order to accommodate the stent's bending. 13. A flexible, expandable stent, comprising: 15 a plurality of flexible cells provided with a plurality *of first loops and a plurality of second loops, said first loops and said second loops disposed and adapted to cooperate so that upon the expansion of said stent the vertical growth of said first loops substantially compensates for the vertical shrinkage of said second loops. 25 loops and said second loops disposed and adapted to cooperate so that upon the expansion of said stent said first loops and said second loops change shape to compensate for the tendency of said stent to foreshorten when said stent is expanded. A flexible, expandable stent having a longitudinal axis, comprising: axis, comprising: O.l U9p\l 8714c AM-0IOM4 -22- a plurality of flexible cells provided with a plurality of first loops and a plurality of second loops, said loops adapted so that said stent prior to expansion is substantially uniformly flexible along its longitudinal axis and bendable in substantially any direction and in several directions at once without affecting the structural or functional integrity of said stent, said first loops and said second loops disposed and adapted to cooperate so that upon the expansion of said stent the vertical growth of said first loops substantially compensates for the vertical shrinkage of said second loops, said loops further adapted to impart rigidity to said stent in an amount sufficient to support a lumen when said stent is expanded. *DATED this 9th day of July, 2004 20 MEDINOL LTD. By its Patent Attorneys DAVIES COLLISON CAVE coo *o*