FR2791551A1 - Expandable stent for supporting blood vessel has tubular stages defined by regular pattern having consecutive loops closed on themselves, with succession of hairpin-shaped apices - Google Patents

Abstract

The stent has a principal axis (1a) and a succession of axially aligned tubular stages (10,20,30), defined by a regular pattern having consecutive loops (40,60) closed on themselves, with a succession of hairpin-shaped apices (3-6) which are connected consecutively, in pairs, by a branch (15,17), each branch having two inflexion points (15a,15b) defining a double inflexion region (19). The loops are arranged in phase from one stage to an adjacent stage and are connected to one another by connecting bars (21) linking the apex region of a loop of a given stage to the region of the inflexion points of a loop corresponding to it axially, in a preceding stage or in a following stage, in an alternating manner on the perimeter of the given stage.

Description

The invention relates to an expandable support for a duct.

  anatomical, and in particular for a blood vessel.

  Such a support is typically called a "stent" when it is a duct expander intended to support the wall of this duct in order to prevent the passage therein (being too) restricted. The object of the invention is to improve the efficiency of the supports

expandable existing.

  The support and the holding conditions of the support, once it has been implanted (therefore deployed radially) in the duct, have been particularly worked on. Indeed, once implanted, the support must have, at its free ends, a diameter in its deployed state at least equal to that of the rest of the structure, and be able to substantially maintain its implantation position, without necessarily including

  hooks or other means of attachment to the wall of the duct.

  It is therefore by relative friction and by its radial bearing force (which is opposed by the radial resistance of the wall of the duct) that the support

  keeps itself in position.

  The ability of the support to follow the natural tortuosity of the duct

  has also been taken into account.

  In terms of implantation, particular attention has also been paid to the ability of the support to be implanted by the endoluminal route ("Seldinger" method, in particular) via a

small diameter introducer.

  To meet these requirements, the solution of the invention consists in particular in providing a support having a one-piece structure having a main axis and, along this axis, a free proximal end and a free distal end, the structure also having a succession of tubular stages aligned axially and interconnected, these coaxial stages defining a substantially cylindrical wall surface of circular section, at least some of these stages being defined by a regular pattern having consecutive meanders closed on themselves along the perimeter of said stage , this support being characterized in that at least one of the stages, respectively first and last, located at said proximal and distal free ends comprises free end apexes having an enlargement along the circumferential wall surface, with at least one component along the perimeter of the structure, in a plane

  perpendicular to the axis thereof.

  With apexes thus widened at the free ends proximal and / or distal of its structure, the support will offer an enlarged surface of support against the internal wall of the duct, thus making it possible to create, in these end locations, zones of increased resistance. to the eventual forces which

  tend to move the support along the conduit.

  In this regard, it has also been noted that it is preferably exclusively along the perimeter of the proximal and / or distal free ends that should be favored (that is to say to increase) the surface of

  contact between this support and its receiving duct.

  Also, another characteristic of the invention provides that the widening of the aforementioned free end apices ends, parallel to the axis of the structure, by a rectilinear section extending along a plane.

  substantially perpendicular to said axis.

  It will be noted that the presence of such a "rectilinear section" also avoids the presence at this location of a shape which could be aggressive with respect to the wall of the duct. In connection with this same consideration, another characteristic of the invention advises that the aforementioned apex enlargements

  each have a substantially triangular shape with rounded angles.

  It will be noted that such a triangular shape makes it possible to reconcile an elongation of the contact surface between said support and the internal wall opposite the duct with the constraint of a shape which promotes this contact in particular along the perimeter of the end stages. concerned, without inducing a shape that can be traumatic for the wall of this conduit. If we are now interested in the rest of the structure at the location of its intermediate stages which extend axially between the first and last stages, it will be noted that, in particular to promote the flexibility and suppleness of the support and to ensure the support effect sought while offering the possibility of implantation by a small diameter introducer, two complementary characteristics of the invention advise that: a) the first and last stages, away from the free ends respectively of the proximal and distal of the structure, as well as the intermediate stages situated between these first and last stages have, at the axial ends of their meanders, apices having a substantially hairpin shape, therefore devoid of said enlargements, b) the consecutive meanders of the intermediate stages of the structure have a succession of apex substantially hairpin, connected consecutively to two x two by a branch, each branch having two points of inflection defining a zone of double inflection, the meanders being arranged in phase from an intermediate stage to an adjacent intermediate stage and being interconnected by bars which connect two stages intermediates determined respectively on the first and last stages of the structure and which also connect the apex zone of a meander of an intermediate stage determined to the zone of inflection points of a meander corresponding to it axially to an intermediate stage adjacent previous or next, alternately on the perimeter of said intermediate floor. In addition, we would also advise that such "hairpin" apices be present at the location of the first and last floors of the structure, between two free end apexes with heads.

enlarged "that we’ve already talked about.

  A more detailed description of the invention will now be

  given with reference to the accompanying drawings in which: Figure 1 shows a general view of a first embodiment of an expandable support according to the invention; Figure 2 is an enlarged local view of the detail marked II in Figure 1; Figure 3 shows on a smaller scale a second embodiment of an anatomical conduit support according to the invention, located inside said conduit; and Figure 4 corresponds to an enlarged view of detail IV of Figure 3

(support only).

  The structures shown in FIGS. 1 to 4 are vessel enlargers (in particular coronary vessel), typically called "stents". The shape of their constitutive structure illustrated in more detail in Figures 2 and 4 could however be used on other types of anatomical supports, such as for example prostheses for aneurysms (realization of the "stent" associated with a flexible sleeve which channels the blood), or internal support for part of the esophagus or for part of

the urethra, for example.

  In other words, the structures illustrated, and in particular the "drawings" which define them, are applicable to the realization of different

anatomical duct supports.

  If we now focus more particularly on FIGS. 1 and 2, the enlarger 1 shown can in particular be used for the treatment of stenosis. I is a hollow cylindrical tube, of axis la, which can occupy in particular two states: a radially tightened state as in Figures 1

  and 2, and a radially deployed state which has not been shown.

  Typically, its axial length is between 9 mm and 30 mm while its diameter (in the tightened state) may be of the order of 1.3 to 3 mm, this diameter possibly increasing to 4 or even 6 mm, in the state

radially deployed.

  The support 1 can in particular be manufactured by laser cutting, from a thin metal plate such as stainless steel type 316L,

  about a tenth of a millimeter thick.

  An embodiment in "thermal shape memory" material, such as

  "nitinol" (registered trademark) is also possible.

  The result is an openwork, one-piece structure.

  In FIG. 2, we can more clearly see the "drawing" of this structure which is in this case identical over the entire surface thereof, except at the proximal lb and distal lc free ends where we find respectively

  the first and last floors, 10, 1.00.

  Thus, can the structure be described as having a succession of stages, as marked 10, 20, 30 in FIG. 2, all staggering along the axis la to individually form an annular cylinder

  with an individual height of between 1 mm and 1.5 mm.

  In this case, the diameter of the ring defined on each stage is constant over the entire length of the "stent", both in the tightened state and

radially deployed.

  It can be considered that each stage extends along a section of cylinder of axis la and that, apart from the end stages 10, 100, each of the intermediate stages located between them is defined by a regular pattern having consecutive meanders closed on themselves with a succession of apices identified 3, 5, 7, 9, 11, 13, 15 for some of them, on the

figure 2.

  We will consider that all these apices located at the axial ends (i.e.

  that is to say ending the meanders of the stage considered along an axis parallel to the axis la) are "hairpin" although each apex is rounded to

to be atraumatic.

  On the same stage, two successive apices are connected by a connecting branch (such as 17 and 19 respectively for the apexes 5-11 and 11-7 of stage 20, in FIG. 2). Each branch has two inflection points, such as 17a, 17b, which define a zone of double inflection, insofar as they are

  relatively close to each other, on the branch considered.

  The meanders thus defined of the stages are arranged opposite one stage to the other, including with regard to the first and last stages 10, 100. Two successive stages are moreover linked together by

connecting bars 21.

  In the figures, these bars are arranged in staggered rows, from floor to floor, that is to say that if we consider a meander (such as 50 on the intermediate floor 20) of a determined connected floor, parallel to the axis la, by a bar 21 to the meander which corresponds to it on the next adjacent stage (30), the two meanders (40, 60) which border it on either side are each connected by another bar 21 to the meanders located in their continuity

  axial, on the previous floor (10).

  With the exception of the two stages of free ends 10, 100 (where the meanders are connected only on one side, to a single stage) the meanders of all the intermediate stages are therefore connected, by stage and on the perimeter of the structure, meanders located in their axial extension upstairs

  previous or next floor, alternately.

  In view of this arrangement, the connection bars 21 can

  be rectilinear bars each extending parallel to the axis la.

  In the illustrated embodiment, it can be seen that, for the balance of the structure, the bars 21 of the meanders 40 and 50 (this is reproducible on the rest of the structure) connect the meanders considered, alternatively to an adjacent "previous" stage (10) or on an adjacent "next" stage (30), from the connecting branch located alternately on one side and the other of the axial end apex considered (such as 3, 9, 5 , 11, 7, ...) (see link at the top left of the apex 3 of the meander 40, then halfway to the left of the apex 5, at the place of the double inflection of the meander 50 between the apexes

axial end 5 and 9).

  The axial length of the bars 21 will moreover advantageously be such that the meanders of the two adjacent stages are axially partially nested, preferably over one to a few tenths of a millimeter approximately (the thickness of the filament of material which

materializes the meanders).

  In addition to what has already been indicated, an important feature of the first and last stages 10, 100 is that each apex of the meanders which constitute these stages has, at the location of the perimeter of the corresponding free ends lb, lc, a widening 23 which are not found elsewhere and in particular not at the location of the "intermediate" apices as identified 25,

  27, 31, 33 in Figures 1 or 2 (apex substantially "hairpin").

  To promote the desired support and retaining effect with respect to the anatomical duct, each enlargement 23 extends along the surface of

  circumferential wall of the structure considered as a whole, i.e.

  say that the enlargements do not protrude radially or inward

  nor towards the outside of the general cylindrical surface of the structure.

  In this case, each enlargement 23 includes a rectilinear "summit" section 29 (which defines its enlarged apex zone) extending along a plane substantially perpendicular to the axis la (plane marked by the line 70 for the end lb and line 80 for the distal end lc, in Figure 1). In view of the general shape adopted for the meanders of the structure, FIGS. 1 and 2 also show clearly that, preferably, each enlargement of said end apex 23 has a substantially "triangular" shape, with rounded angles 32, particularly

  adapted from the overall "drawing" already presented.

  In the variant embodiment of FIGS. 3 and 4, the drawing of the structure which defines the wall surface in the form of an annular cylinder of the tubular support 90 is, as before, identical over the whole of this tubular surface, except at the location of the two end stages 110, 200, located

  respectively at the proximal end and the distal end of the support.

  Again, the structure can be made of metal and is in one piece.

  As in the case of Figures 1 and 2, the support of Figures 3 and 4 is intended to be deployed radially from the shape illustrated in the figures (see arrows in Figure 3) from their radially tightened state illustrated, under the effect in particular of an inflatable internal balloon (not shown), or even of a thermal effect if the material used is a "material

with thermal shape memory ".

  In Figure 3, the anatomical receptor duct (coronary vessel

in this case) was identified 91.

  To return to the drawing of the structure 90, it will be noted that two consecutive stages (such as 110, 120 and 120, 130 in FIG. 4) are interconnected by connecting bars 93 elongated in a direction parallel to

  the axis 90a of the support and arranged in a concise fashion.

  As before, each stage develops by closing on itself (in the manner of an elementary ring) along a plane perpendicular to 90a, so that we can consider that the structure presents a succession of annular stages staggered regularly the

along this axis 90a.

  Each stage is further defined, once again, by a thin strip of meandering material having a succession of hollows and vertices. This meandering shape is distributed, for a given floor (such as floor 120), alternately above and then below a perimeter (fictitious) center line marked 95 for this floor and located in a plane

perpendicular to the axis 90a.

  On either side of this line (which can easily be imagined for each of the stages), the aforementioned wavy shape alternately has two successive vertices directed upwards, 97a, 99a, then two successive vertices directed downwards, 97b, 99b, thus defining in a way, alternately on one side and the other of the "midline", a series of two hairpin apex arches arranged side by side and joined by a rounded intermediate hollow ( such as 101 for the vertices 97a, 99a) which extends substantially to the aforementioned center line, thus giving each of the series of meanders successively situated on either side of

  said "center line" has a shape substantially with two nested "S" s.

  Given the arrangement in phase opposition of the stages, the bottoms of two recessed areas, such as 101, 103 in FIG. 4, are connected

between them by a bar 93.

  These staggered bars are connected substantially at mid-

  height of the stages, the connection being effected with each of the internal branches 105, 107 of the corrugations opposite, while between these two opposite connection zones, the bars appear as a single refined strip, thus giving an appearance of "two Y 'inverted, connected by

their foot.

  In view of the above, the bars and the undulations of the stages thus define a series of cells 109, all identical (except at the end stages 110, 200) having in any case substantially the shape of two "H" side by side. coast with a common central vertical branch 111 plus

  shorter than the two outer vertical branches.

  At the ends of the ends 90b, 90c, we will see that we find the enlargements of the apexes marked here 111 for the end 90b on

Figure 4.

  The effect sought for these enlargements is the same as that already

  stated in relation to Figures 1 and 2 (end diameter, support).

  It should also be noted that said enlargements 112 are found at

the end 90c (see Figure 3).

  Each enlargement (such as 112) extends along the circumferential wall surface of the structure, as before, with at least

a perimeter component.

  In fact, each enlargement integrates a rectilinear "summit" section, such as 113, again extending exclusively along a plane substantially perpendicular to the axis 90a (plane materialized by the line

  in Figure 4 for enlargements 112).

  As with regard to FIGS. 1 and 2, the enlargements of the proximal and distal ends of the structure of FIGS. 3 and 4 imply a curvature of the outer branches 117, 119 which each connect a widening to an opposite "summit" apex (such that 121, 123) meanders

  of the end stage considered (110, in this case).

  It is thanks to this shoulder-shaped curvature marked 125 that

  the desired end widening can be obtained.

  In FIG. 4, it will have been noted that the "summit" apexes of the stages of free ends situated opposite the enlargements are substantially "hairpin", like all the other apexes of the meanders of the intermediate stages.

  The use of supports 1, 90 is traditional.

  After having placed them around their inflatable balloon (if they are not with thermal shape memory), they are placed in an introducer and they are introduced into their receiving duct (coronary) inside which they are deployed by swelling of the balloon (see FIG. 3, arrows) until they come to bear against the internal wall of said duct (wall 91a in FIG. 3). The introduction system is then removed and the support left in

square.

Claims (6)

Claims   1. Expandable support for anatomical duct, the support having a monobloc structure, having a main axis and, along this axis, a free proximal end (2, 90b) and a free distal end (12; 90c), the structure also having a succession of tubular stages (10, 20, ...;, 120, ...) aligned axially and interconnected, these coaxial stages defining a substantially cylindrical wall surface of circular section, at least some of these stages being defined by a regular pattern having meanders (40, 60, ...) consecutive, closed on themselves along the perimeter of said stage, characterized in that at least one of the stages, respectively first (10, 110) and last (100, 200), located at said proximal and distal free ends comprises free end apices having a widening (23, 112) along the wall surface   circumferential, with at least one component along the perimeter.   2. Support according to claim 1, characterized in that the meanders (40, 60, 80, ...) consecutive intermediate stages (20, 30, ...) located between said first (10) and last (100) storeys of the structure have a succession of apices (4, 6, 8, ...) substantially in hairpin connected consecutively in pairs by a branch (17, 19, ...), each branch having two points d inflection (17a, 17b) defining a zone of double inflection the meanders being arranged in phase from an intermediate stage to an adjacent intermediate stage and being interconnected by bars (21) which connect two determined intermediate stages, respectively to the first (10) and at the last (100) stages of the structure and which also connect the apex zone of a meander of a determined intermediate stage to the zone (17a, 17b) of the inflection points of a meander axially corresponding to a previous adjacent intermediate stage or   next, alternately on the perimeter of said intermediate floor.   3. Support according to claim 2, characterized in that between two successive free end apices (23, 112) of the first (10, 110) and / or the last (100, 200) stages of the structure, the meander correspondent present   at least one hairpin apex (25, 27, 29).   4. Support according to any one of the claims   previous, characterized in that the widening of the free end apices ends, parallel to the axis of the structure, by a rectilinear section (29, 113) extending along a plane (70, 80) substantially perpendicular said axis.   5. Support according to any one of the claims   previous, characterized in that the enlargement of the free end apices has a substantially triangular shape, with rounded angles (32) (see figure 2).   6. Support according to claim 1, characterized in that: - the first and last stages (10, 100; 110, 200), away from the free ends (lb, lc; 90b, 90c) respectively proximal and distal of the structure, as well as the intermediate stages (20, 30, ...; 120, 130, ...) located between these first and last stages, have apexes at the axial ends of their meanders (9, 11, 25, 27 , ...; 121, 123, ...; 97a, 97b, ...) having a substantially hairpin shape   hair, therefore devoid of said enlargements.