WO1996041590A1

WO1996041590A1 - Endo-luminal implant

Info

Publication number: WO1996041590A1
Application number: PCT/IB1996/000566
Authority: WO
Inventors: Jean-Claude Sgro
Original assignee: Cogent
Priority date: 1995-06-09
Filing date: 1996-06-07
Publication date: 1996-12-27
Also published as: FR2735016A1; AU5776496A; FR2735016B1

Abstract

The invention concerns an endo-luminal implant comprising a plurality of mutually independent support rings (11 to 14) which have a common axis and are each integral with a flexible structural peripheral side member (6) which extends at least in the longitudinal direction of the implant, from one end thereof to the other. The rings and the side member are produced from a single filament (1) which is shaped in three dimensions along a substantially closed continuous line which defines in space a substantially tubular enveloping surface, and an alternating line on either side of a circumferential median line (4) centred on said axis, defining at least three loops (a to f) in the tubular surface determined by the series of enveloping surfaces of the respective support rings (4).

Description

ENDO-LUMINAL IMPLANT The present invention relates to an endo-luminal implant, of generally substantially tubular shape, which can be inserted and put in place surgically in any anatomical duct in humans or animals, for the purpose of maintaining or restoring a passage in said conduit.

Such implants are well known in the medical and surgical art, under the English term "stent", and are, in particular, used or used to treat in man his arteries, in particular the coronary artery, following an endoluminal angioplasty for example.

The present invention relates more particularly to implants having a low "shape memory", or a certain plasticity, due for example to the constituent material, in particular metallic, selected for its production or manufacture. Starting from an initial conformation that is relatively picked up in a centripetal manner, favoring its introduction and its displacement in the anatomical duct treated, such an implant can take, once put in place and positioned in said anatomical duct, an expanded or deployed conformation centrifugal, final, relatively resistant radially, so as to support and spread, and in a way, support the wall or the anatomical duct treated. The transition from the collected conformation to the expanded conformation is obtained under the effect of a radial thrust applied to the interior of said implant, both along its entire length and along its entire circumference.

Such implants are generally used at the active distal end of a catheter or endoscope, provided with an inflatable or expandable balloon, around which the implant is placed and maintained in its collected conformation. This endoscope is introduced into the anatomical conduit to be treated, for example the artery, until reaching the area to be opened or kept open. At this point, the balloon is inflated to expand or distend the implant in its final deployed conformation, then it is deflated and extracted from the treated anatomical canal, leaving the implant in its position and final expanded conformation, ie ie without returning to the picked-up conformation of said implant.

In accordance with document US-A-4 135 536, a balloon-expandable stent has been described, consisting of a single filiform element, this being formed in a series of forestay rings independent of each other, but integral each of at least one structuring, peripheral and flexible spar, extending at least in the longitudinal direction of the implant, from one end to the other of the latter, in the tubular surface determined by the succession or series of Envelope surfaces of the different forestay rings respectively. The rings are connected to each other longitudinally by welding points, at the level of two loop vertices opposite two adjacent rings, so as to form the spar. The loops formed by the filiform element are not equal, on either side of a median line, which requires prior bending of the single complex wire, in order to be able to weld the tops of the loops, in an aligned manner. This way of folding and connecting the tops of the different rings gives a fragile connection, because the welds are subjected to longitudinal mechanical stresses essentially in traction, when the prosthesis is dilated.

The present invention has proposed to solve the problems of the prior art by providing an implant similar to that defined in the previous document, but easier to manufacture, and which also has, due to its particular structure, a large resistance to longitudinal mechanical stresses exerted by the expansion of the prosthesis.

In accordance with the present invention, an endoluminal implant is proposed, intended to be implanted in an anatomical duct of man or animal, for the purposes of maintaining or re-establishing a passage in said duct, obtained in a constituent material with relatively weak shape memory, comprising:

- A plurality of forestay rings, distributed in a longitudinal direction, having a common axis, independent of each other, but each secured to a peripheral structural beam, flexible, extending at least in the longitudinal direction of l implant, from one end to the other of the latter, the rings and the spar being produced from a single filiform element, in particular wire, obtained from said constituent material, running from one end to the other of said implant;

the filiform element being shaped in three dimensions along a substantially closed continuous line, defining in space a substantially cylindrical envelope surface, and in said envelope surface an alternating line on either side of a line circumferential median centered on said axis, and defining at least three loops whose rounded vertices are arranged alternately on one side and on the other side of said median line, in the tubular surface determined by the succession of said envelope surfaces of said rings respectively. The implant is more particularly characterized in that the filiform element is further shaped, to present between three successive rings;

a longitudinal connecting strand belonging both to a reference branch of a reference loop of a said ring, and to a branch of a loop of the ring following said ring, and a second strand longitudinal link belonging both to said reference branch of said reference loop of said ring, and to a branch of a loop of the ring preceding said ring; - And an extreme longitudinal strand of the same filiform element belonging to a branch of a loop of an extreme ring, and the other extreme longitudinal strand of the same filiform element belonging to a branch of a loop of the other extreme ring; - The longitudinal strands being assembled and secured two by two at each forestay ring, to together constitute said flexible spar.

Thanks to the endolumnial implant according to the invention, it also becomes possible to expand or expand in a differentiated and independent manner, the different forestay rings respectively, which makes it possible to better adapt to the configuration of the conduit. anatomically treated, the lumen of which may have a variable or irregular section depending on its length. Thanks to the invention also, in the event of a significant expansion or distension of a forestay ring, the flexible peripheral spar can locally assume, that is to say at the level of the distended ring, an oblique conformation, participating in the expansion of said ring, and absorbing, in a way, its excess distension. In this way the connections securing the two strands at each ring work in shear in the direction of longitudinal traction and essentially along the axis of the implant, and not perpendicular thereto. This particular structure thus makes it possible to limit the risks of embrittlement and breakage of the connections in the form, for example, of welds, unlike implants known from the prior art.

The present invention is now described with reference to the accompanying drawing, in which: FIG. 1 represents, in its final expanded conformation, an implant according to a first embodiment of the invention; FIG. 2 represents the implant of FIG. 1, in its initial picked-up conformation;

FIG. 3 is a partial elevation view of the implant shown in FIG. 1, at the level of a forestay ring; FIG 4 is a sectional view along line IV-IV of Figure 3 of the forestay ring shown in Figure 3; FIG. 5 is an elevation view of the ring shown in FIG. 3, from another angle of observation; FIG. 6 is an elevation view, in its final expanded configuration, of an implant according to the embodiment of FIG. 1 of the invention; FIG. 7 is an elevation view, in its final expanded configuration, of an implant according to a second embodiment of the invention; FIG. 8 is a schematic view of the prior folding of a single wire constituting the implant according to the invention during the manufacture of the latter; FIG. 9 is a front view of a forestay ring of an implant according to a third embodiment of the invention;

FIG. 10 is a front view, according to another angle of observation of the forestay ring shown in FIG. 9,

FIGS. 11 and 12 are sectional representations, respectively along lines XV-XV and XVI-XVI of FIG. 8, of the forestay ring shown in FIG. 8.

In accordance with FIGS. 1 to 6, an endo-luminal implant according to the invention is obtained or produced from a constituent material having finally, that is to say after production of the implant and possibly subsequent heat treatment of the latter, a low shape memory, or a certain plasticity or malleability, while retaining sufficient rigidity to avoid any return of the expanded form of the implant to its initial collected form. Such a constituent material may be a metal or a metal alloy meeting these characteristics, for example stainless steel, titanium, tantalum, gold, platinum, etc., or any other biocompatible material, in particular material plastic, with the required mechanical characteristics. As shown in FIGS. 1 and 2, and taking into account the intrinsic mechanical properties of the material constituting the implant according to the invention, the latter is capable of assuming an initial picked-up conformation, of relatively small section, shown in FIG. 2, and an expanded, final conformation, of relatively large section, relatively resistant to any radial force, shown in FIG. 1. The passage from the collected initial conformation to the final expanded conformation is obtained, as already indicated, under the effect of a radial thrust applied inside the implant, both along its entire length and along its entire circumference.

In general, the structure of the implant according to the invention comprises: a plurality of forestay rings 11 to 14, each determining a surface of tubular or cylindrical casing, distributed in the longitudinal direction of the implant, independent of each other, in the sense that the said rings are not directly linked or integral with one another, and distant or separated from each other; -a structuring spar, peripheral or lateral, flexible, extending at least in the longitudinal direction of the implant, from one end to the other of the latter, in the tubular surface determined by the succession of the surfaces of envelope of rings 11 to 14 forestay respectively; each ring 11 to 14 is integral with the spar 6, along approximately a generatrix of its aforementioned envelope surface, of tubular or cylindrical shape. Each forestay ring 11 to 14, as well as the spar, is obtained from a single filiform element 1, obtained from the aforementioned constituent material, composed by forming four sections 21 to 24 connected together by the single and even filiform element, and respectively defining the forestay rings 11 to 14.

As shown more particularly in FIGS. 3 to 5, each forestay ring, for example 12, is constituted by the corresponding section 22 of the filiform element 1, shaped in three dimensions, according to a substantially closed continuous line, defining in l space a substantially cylindrical or tubular envelope surface. In this envelope surface, the section 22 of the filiform element defines an alternating line on either side of a median line 4, circumferential, centered on the axis 3, common to all the forestay rings 11 to 14 in the expanded or collected conformation of the implant. Still in this cylindrical envelope surface, the section 22 of the filiform element 1 defines six loops a to f, each having the shape of a pin with branches parallel to each other and to axis 3, in the expanded conformation of FIG. 1. The rounded tops of these loops a to f are arranged alternately on one side and the other of the center line 4. By "filiform element" is meant any element generally having the shape of a wire, obtained from the aforementioned constituent material, composed of yarns or filaments proper, linked to each other by any appropriate means, such as twisting or braiding for example. As shown more particularly in FIG. 1, the forestay rings 11 to 14 are distributed according to the longitudinal direction of the implant, being oriented angularly with respect to the axis 3 of said implant, and with respect to each other, so that the rounded tops of a ring, for example 12, located in the same side of the latter, adjoin the hollows of the next ring, for example 13, located on the side adjacent to the same side; in a way, depending on the length of the implant, the loops are arranged relative to each other, "head to tail". And the forestay rings 11 to 14 are offset angularly with respect to each other, around the axis 3, so that the vertices in correspondence of the six loops a to f, of the different rings 11 to 14 respectively, determine at at least three lines, for example six helical lines, included in the tubular surface of the implant, determined as said above by the succession of the envelope surfaces of the different forestay rings 11 to 14.

It therefore follows from the foregoing description that each forestay ring 11 to 14 has a largely perforated outer surface, limiting in particular to what is strictly necessary the contact between the implant and the wall of the anatomical canal.

In accordance with the first embodiment of the invention, the spar 6 and the various forestay rings 11 to 14 are produced from the one and the same filiform element, running from one end to the other of the implant, passing through the sections 21 to 24 described above, shaped to constitute the four successive rings 11 to 14 respectively. The spar 6 is obtained by forming the aforementioned filiform element, by bringing together in a single line, arranged in the tubular envelope of the implant, different longitudinal strands, formed at the level of the different rings respectively, and by joining them together to constitute together the aforementioned spar. Referring to the forestay rings 11 to 13, the spar 6 is obtained in the following manner: a longitudinal strand, the link, belongs both to a reference branch dl of a reference loop d of the ring 12, and to a corresponding branch dl of a corresponding loop d of the following ring 13; a second longitudinal strand lb of connection belongs both to the reference branch dl of the reference loop d of the ring 12, and to a corresponding branch dl of a corresponding loop d of the previous ring 11; an extreme longitudinal strand 1 of the filiform element 1 belongs to or is connected to a branch dl of a loop d of the extreme ring 11, while the other extreme longitudinal strand ld of the same filiform element 1 belongs to or is integral of a branch dl of a loop d of the other end ring 14; as shown in FIG. 1, the longitudinal strands are brought together or brought together two by two, at the level of each ring 11 to 14, to constitute and determine together the flexible spar 6.

As shown in Figure 1, the beam 6 has a profile describing in the tubular surface of the implant, a helix slightly inclined relative to the axis 3 of said implant.

As shown in Figure 2, the initial conformation picked up is obtained by forcing into contact with each other, the ends of the two branches of the different loops a to f of the different rings 11 to 14. In compliance with the elastic limit of the constituent material, the initial conformation can be even more compacted, by crossing these same branches of the aforementioned loops.

And, in accordance with FIG. 1, the expanded conformation is obtained by separating these same branches from the same loops a to f, so as to bring them into a position parallel to each other, and to axis 3, like a "U".

FIG. 6 illustrates more clearly the embodiment according to FIGS. 1 to 5, by showing that the longitudinal strands 1a to 1d are joined together in pairs, for example by welding, so as to obtain the spar 6.

According to the second embodiment according to FIG. 7, these same longitudinal strands 1a to 1d are joined two by two, by links 8, always so as to obtain the spar 6.

Figure 8 shows schematically how the implant is made. This implant is easier to manufacture than those known from the prior art, in that it consists of a single filiform element folded in equal alternating lines or loops and in single steps. The implant can thus be manufactured by simple helical winding of the filiform element around a mandrel, for example, by gathering the longitudinal strands la to ld and by joining them two by two at each ring 11 to 14 of forestay, to constitute together said flexible beam 6.

The third embodiment of the invention described with reference to FIGS. 9 to 12, differs from the first embodiment, in that each forestay ring 11 to 14, for example 12, has eight loops, determined by the corresponding section, for example 22, of the filiform element.

Not shown, the filiform element 1 can be covered with a biologically compatible material, protecting it on the one hand, and insulating it from the wall of the anatomical duct, on the other hand. A protective sleeve, always made of compatible material, can cover the entire implant, for example for its introduction into the anatomical canal.

Claims

1 / Endoluminal implant, intended to be implanted in an anatomical conduit of the man or the animal, in order to maintain or restore a passage in said conduit, obtained in a constitutive material with relatively weak shape memory, comprising :

- A plurality of forestay rings (11 to 14), distributed in a longitudinal direction, having a common axis, independent of each other, but each secured to a beam (6) structuring peripheral, flexible, extending at least in the longitudinal direction of the implant, from one end to the other of the latter, the rings (11 to 14) and the spar being produced from one and the same filiform element (1), in particular wire, obtained from said constituent material, running from one end to the other of said implant;

the filiform element being shaped in three dimensions along a substantially closed continuous line, defining in space a substantially cylindrical envelope surface, and in said envelope surface an alternating line on either side of a line circumferential median (4) centered on said axis, and defining at least three loops (a to f) whose rounded vertices are arranged alternately on one side and on the other side of said median line (4), in the tubular surface determined by the succession of said envelope surfaces of said rings respectively, characterized in that raw the filiform element (1) is further shaped, to present between three successive rings (11 to 14);

- a longitudinal strand (la) belonging both to a reference branch (dl) of a reference loop (d) of a said ring (12), and to a branch (dl) of a loop ( d) of the next ring (13), said ring (12), and a second longitudinal connecting strand (lb) belonging both to said reference branch (dl) of said reference loop (d) of said ring (12), and to a branch (dl) of a loop (d) of the ring preceding (11) said ring (12); - and an extreme longitudinal strand (le) of the same filiform element belonging to a branch (dl) of a loop (d) of an end ring (21), and the other extreme longitudinal strand (ld) of the same (dl ) filiform element belonging to a branch (dl) of a loop (d) of the other extreme ring (14); - The longitudinal strands (la to ld) being assembled and secured two by two at each ring (11 to 14) forestay, to together constitute said flexible spar (6).

2 / Implant according to claim 1, characterized in that the strands (la to ld) are joined two by two by welding (7) or links (8) joining them.

3 / Implant according to claim 1, characterized in that the beam (6) has a profile describing in the tubular surface of the implant a helix slightly inclined relative to the axis (3) of said implant.

4 / Implant according to claim 1, characterized in that the section of the filiform element (21 to 24) of each ring (it to 14) of forestay describes in its envelope surface an alternating line linking six loops (a to f), whose rounded vertices are arranged alternately on one side and the other of the center line (4) of said alternating line. 5 / implant according to claim 1, characterized in that the rings (11 to 14) are distributed in the longitudinal direction of said implant, being angularly oriented with respect to the axis (3) of said implant, and each with respect to others, so that the rounded tops of a ring (12), situated on the same side of the latter, adjoin the hollows of the next ring (13), located on the side adjacent to the same side.

6 / implant according to claim 5, characterized in that the rings (11 to 14) are angularly offset with respect to each other, around said axis (3), so that the vertices in correspondence of the loops (a to f) different rings respectively determine at least three helical lines in the envelope surface of the implant. 7 / implant according to claim 1, capable of assuming an initial picked-up conformation (FIG. 2), in which the two branches of the different loops (a to f) are at their respective ends in contact with one another, and under the effect of a radial thrust applied inside said implant over its entire length and circumference, an expanded conformation (Fig. 1) in which these same branches are spaced apart from each other, characterized in that , in said deployed conformation, the branches of the loops (a to f) of the implant are each parallel to the axis (3) of the latter.

8 / implant according to claim 1, characterized in that it is covered by a protective sleeve, or coated with a biocompatible material.