FR2777450A1 - Vascular aneurism treatment assembly - Google Patents

Abstract

The assembly consists of a tubular prosthesis (1) which is inserted into the aneurism (23), and fixings (11) and seals (29) applied to the outside of the vessel. The prosthesis has zones (d) such as accordion pleats to absorb variations in length, and is held in place by fasteners (13) such as rivets or sutures which pass through the vessel wall and are fitted laparoscopically.

Description

The invention relates to a medical device for treating (at

  less) a vascular aneurysm, such as in particular an aortic aneurysm.

  One of the problems encountered on these prostheses relates to the implantation technique used and in particular, the way in which it is planned to fix the prosthesis to the vessel at its "upstream" end, there where the prosthesis receives the (or most of the du) blood flow (the term "upstream" referring to the considered area of the prosthesis in relation to the sense of

  circulation of this "main" blood flow).

  In US-A-5,527,355, there is thus described an apparatus and a method for treating aneurysms by applying a band around the outer surface of the vessel, at the places where the means for

  holding the prosthesis against this vessel (stents).

  In other words, it is known from this patent: - an aneurysmal prosthesis adapted to be introduced into the vessel up to the location of the aneurysm (s) and comprising a flexible sleeve for channeling the blood therein and a structure in stent (s) linked to the sleeve, the prosthesis having an axis and a length along this axis, - as well as fixing means and sealing means linked to manufacturing (that is to say integrated) to the prosthesis or adapted to be subsequently linked to it to fix the flexible sleeve to the internal wall of the vessel, in a blood-tight manner, towards said "upstream" and "downstream" ends

aneurysm (s).

  With this prosthesis, a problem remains despite everything, namely that posed by the consequences, for the vessel, of the forces exerted on it by the prosthesis (in particular, by means of its fixing means,

even sealing).

  However, the applicant has just demonstrated that if the sealing is effective, then significant efforts are exerted at the location of the fixing of

the prosthesis to the vessel.

  Drying of the aneurysmal area may be the cause. One of the objects of the invention is to reduce the importance of these efforts, by also avoiding the "plicature" zones (crushing or radial collapse of the prosthesis, detrimental to the good circulation of blood). The solution of the invention consists in that the prosthesis has

  fractional zones of absorption of a variation of its length.

  Another problem which the invention takes into account concerns the

  way to attach the prosthesis to the vessel.

  A preferred solution consists in that the fixing means comprise means other than usual "hooks" for anchoring and which pass entirely through the wall of the vessel. A suture with biocompatible thread (s) or a staple system or rivet (s) as in FR 97 16625 or FR 97 15969 are in particular recommended, in addition to or in replacement of said anchoring "hooks" typically provided hitherto on the stents of aneurysmal prostheses, in particular towards their

  "upstream" end (see for example US-A-5,527,355).

  Another problem which the invention addresses relates to the technique of fitting the fixing means and sealing means which will have

been retained.

  In this regard, the "downstream" aneurysmal area must be separated from the

"upstream" aneurysmal area.

  Indeed, at the "downstream" end, one can use the technique presented in FR-A-2 748 198, that is to say provide a stripping of this area, by a relatively light surgery, then come to anastomose the vessel (or an intermediate vessel substitute) to revascularize the "downstream" end of the flexible sleeve of the prosthesis, using for this

  in particular one or more surgical sutures.

  At the "upstream" end of the prosthesis, we advise not to

  do so. An endoscopic approach is recommended.

  Thus, an additional characteristic of the invention preferably provides for the use of means for endoscopic extravascular placement, at least means for sealing the prosthesis when the latter comprises, as indicated below, in particular a lining. external to be put in place around a part of the vessel, these endoscopic means being preferably also used for the establishment of the fixing means if these are of the "rivet" or "staple" type transversely passing through the opposite vessel from the "upstream" end of the prosthesis,

  from the exterior to the interior of the vessel.

  Regarding the sealing means, it is also advisable to use at least one external lining of this vessel, to be placed facing the upstream end of the prosthesis, this lining being presented as an element or pad adapted to surround a part only of

the periphery of said vessel.

  Such an element in the form of a washer or "split" ring is preferred. For the quality of the seal and, importantly, for good solidity of the vessel wall opposite the "upstream" end of the prosthesis, it is also advisable to add to the above-mentioned external lining, a inner lining, this inner lining being linked by

  prosthesis manufacturing (at least towards its "upstream" end).

  Another aspect to which the invention is concerned relates to the manner of producing the "fractioned zones" for absorbing variations in

  length of the prosthesis when the aneurysmal area dries up.

  A first alternative embodiment consists in that these divided zones comprise formed accordion beads or bellows

  on the sleeve and adapted to shorten, more than to lengthen.

  This solution is a good compromise between the requirement to absorb essentially axial stresses and that of radial crushing resistance while allowing an axial offset between the upstream "and downstream" of the implant. According to an additional characteristic, these beads or accordion bellows will preferably be present on the sleeve in several separate places (sections) axially distant from each other. This will avoid creating an accordion area that is too large

  length which could favor the appearance of a plication.

  According to an alternative or complementary solution, provision could also be made for the structure in stent (s) to be distributed over several levels, along the axis of the prosthesis, at least some of these levels being independent two by two, the divided zones " antiplicature "then being, at least for some, defined by a space established axially between two

  successive independent stent levels.

  This will combine flexibility requirements, resistance to

  crushing, quality of fixing, sealing and "anti-splicing" effect.

  A more detailed description of the invention will now be

  provided with reference to the accompanying drawings in which: - Figure 1 is a schematic view of an aneurysm prosthesis inside its receptor vessel, - Figure 2 is an enlarged local view showing in particular a fastening rivet of the prosthesis to the vessel, - Figure 3 shows a sealing pad in the shape of a washer, - Figure 4 shows an alternative embodiment of a prosthesis for aneurysm, - Figure 5 shows, on a reduced scale, the rivet of Figure 2 with its implantation means (diagram), - Figure 6 shows a needle and a suture, - Figure 7 shows a laparoscopic pliers type tool, - Figure 8 shows in local view an alternative embodiment to the stent structure of FIG. 1, FIG. 9 shows an alternative embodiment, at least locally, of the lower extension part of the sleeve of the prosthesis of FIG. 4; - And Figure 10 shows a sealing ring outside the

  vessel provided, at the location of its slit, with a suturable "tissue" extension.

  In Figure 1 first of all, a prosthesis is shown

  "traditional" for aneurysm, 1.

  This implant includes a flexible sheath 3 "usual", typically

  made of tissue and adapted to channel blood through it.

  A frame consisting of a stent structure identified as a whole 5 provides mechanical resistance to the sheath 3, by being linked to it

  by one or more surgical sutures 7.

  Structure 5 can occupy two states: - a first state of restricted diameter (not shown), for the introduction of the implant inside the receptor vessel (typically using the "SELDINGER" method), - or a second state of larger diameter (see FIG. 1) in which the implant is at least locally substantially applied against the

inner wall of the vessel.

  The stent structure 5 may consist of self-expanding stent (s) typically made of metal such as stainless steel, or else

  be expandable (s) via an inflatable balloon (not shown).

  An embodiment of shape memory material, in particular based on a

  nickel / titanium alloy (Nitinol, registered trademark) is also possible.

  In the example of FIG. 1, the stent structure 5 is staggered over several stages, in this case 5a, 5b, 5c, 5d. Each stage consists of a corrugated metal wire (such as a zigzag) closed on itself

  to form a cylindrical ring of variable diameter.

  The stages 5a and 5d are located respectively towards the ends

  free "upstream" (with respect to blood flow), the, and "downstream", lb, of the implant.

  The structure 5 can be arranged inside or outside the sleeve 3 which is itself tightened or radially deployed (relative to the axis 9 of the implant), depending on the radial state of the structure 5. Note that a form other than corrugated wire (s) could be

retained for structure 5.

  For its attachment to the vessel 10 after being positioned inside, the implant 1 may include anchoring hooks such as 11,

  having a tip adapted to penetrate the wall of the vessel.

  Typically, these hooks are metallic and welded or formed with the stent structure. In FIG. 1, they protrude from the "upstream" end 1a and

are linked to stage 5a.

  In addition to or in substitution for such hooks, it is however advisable to use other fixing means associated with complementary sealing means, both at the "upstream" end and at the end.

"downstream" lb of the implant.

  As described in FR 97 16625, filed on December 29, 1997, these are fixing means which will pass through the entire wall of the vessel 10, and / or which will be fixed therefrom from the outer wall of the vessel (unlike hooks 11 which are not supposed to pass through this wall and which hang on

from inside the ship).

  As illustrated in FIG. 2, it may in particular be a fastening system with rivets 13, with a radially deployable head 15, extended by a body 17 having locking notches 19 intended to prevent the turning back of a slide 21 movable along the rod 17 only towards the head 15, in order to clamp, between itself and the head, the vessel 10 and the implant 1, which have previously been crossed by this head 15, as

  this is clearly explained in FR 97 16625.

  In place of the rivets 13, another effective fixing technique may consist in suturing (by one or more known surgical suture threads) the implant to the vessel, a priori from the exterior of the vessel,

  then using an endoscopic or laparoscopic approach, extra-

  vascular. Whatever these transvascular fixation means, these will be present both at the "upstream" end 23a and at the "downstream" end 23b of the aneurysm shown diagrammatically in FIG. 1 where we have materialized by features

  mixed the possible location of the two levels of rivets 13.

  These fixing means are associated with sealing means to prevent blood flow (arrow 25 for the main flow), from still passing into the aneurysmal pocket 27 (directly or by "reflux" via

collateral vessels).

  As already described in FR 97 16625, these sealing means comprise at least one pad for the inner and / or outer lining of the

  vessel at the "upstream" and "downstream" ends of the aneurysm and / or implant.

  Each wall lining will advantageously be presented as a thickness pad adapted to absorb irregularities in the vessel.

  against which it should be applied.

  As described in FR 97 16625, this buffer lining may have a layer promoting adhesion to the vessel (polyester, "Teflon" foam, registered trademark), on one side, and on the other, a layer of "non adhesive ", such as silicone. It may also include a more rigid, elastically deformable core or structure, if a mechanical shaping effect (in particular in "C") is desired (trellis, light metal frame, etc.), as well as one or more several orifices to facilitate the passage of the fixing means through it, or alternatively (as an alternative) to be coated with a coating suitable for being sutured to the vessel. In FIG. 2, two sealing buffers 29, 31 have been shown, respectively arranged between the rivet clamping slide 21 illustrated 13 and the vessel 10 (external buffer 29) and between this same vessel and the implant 1 ( inner pad 31). If the retained fixing means pierces the vessel with a risk of leakage at this location (case of the rivet 13, or possibly a fastening by staple), two such sealing pads are recommended, even if possibly the inner pad 31 which was attached to implant 1 (for example, by suture) during its manufacture (or at least before it was introduced into the vessel) could be

  deleted, if the clamping effect by the enlarged head 15 is sufficient.

  In the case of a smaller perforation of the vessel (needle and surgical suture (s) in particular), then the use of only one of the two pads 29, 31, may be sufficient, the choice being made by depending on the implantation conditions: - either it is easier (despite the local increase in diameter) to set up an implant 1 with pads 31 previously fixed externally to it at the place of the "upstream" sealing zones and "downstream" predetermined, - this is problematic, and then we choose to set up the external "upstream" and "downstream" buffers 29, in this case using endoscopic or laparoscopic means of positioning

  extravascular (see FR 97 16625 and below).

  As illustrated in FIG. 1, the "upstream" and "downstream" external sealing pads can be presented as a split ring, so that they can be deformed flat for an endoscopic introduction, the ring preferably having a tendency to resume of itself its arched shape, without constraint. As an alternative, these pads may however consist of washers made of the aforementioned material and marked at 29a in FIG. 3. Each washer has a central orifice 31a, avoiding having to pierce the pad when the means are put in place. fixing through, although the strip 29 may have been pre-punched or precut (cutting

  cross, for example) in predefined locations.

  It will be understood that the rod 17 of the rivet 13 is intended to pass through the orifice 31a. The advantage of such sealing washers is that they can be mounted in advance around each rivet to be introduced into the patient's body. The footprint is also less, compared to the solution to

"strip" in Figure 1.

  In FIG. 4, an alternative is shown schematically

  embodiment, marked 30, of the aneurysm prosthesis of FIG. 1.

  More specifically, it is an "extension" aneurysmal prosthesis of the type described in FR-A-2 748 198 or in US 08/672 349 filed on

June 1996.

  In summary, it is a prosthesis having axially a much greater length than that of FIG. 1. In addition, the stents of the frame 35 do not extend, from the "upstream" end 30a, only on a section 33 beyond which the sheath 37 for channeling the blood is

  structured by no frame and, in particular, no stent.

  Advantageously, on this second section 39 (which extends to the "downstream" end 30b of the prosthesis), the sheath may have longitudinally a succession of accordion beads, typical of the "old" aneurysmal prostheses put in place by non-endoluminal surgical route (as in WO-A-88/06026) and allowing, in particular,

  this portion 39 to naturally occupy a radially open state.

  At the "upstream" end 30a, the fixing of the prosthesis 30 to the vessel is intended to be carried out in one of the ways presented above in

relationship with the implant 1.

  On the other hand, at the "downstream" end 30b, it is a surgical suture, with local opening of the patient's body until this end 30b appears, which is recommended, since it is such a recovery technique "downstream" surgical procedure which is presented in particular in

FR-A-2 748 198 or US 08/672 349.

  In connection with this, we return briefly below to the recommended techniques for fitting prostheses 1 and 30. The introduction of prosthesis 1 takes place in a known manner. After having arranged a transcutaneous approach and having determined a jugular or femoral approach, the "SELDINGER" method is applied. One or more inflatable balloon (s) can be used (as described in US-A-4,733,665 which provides

the use of a balloon).

  While the implant is maintained, but not yet (sufficiently) fixed inside the receiving vessel, we just put in place, from the outer periphery of this vessel, the final fixing means which will ensure the securing from the latter to "healthy" vascular wall areas

  located beyond and below the aneurysmal area.

  If these transvascular fixing means each correspond to the rivet 13 in FIG. 2, then one can use endoscopic or laparoscopic introduction means for them, as marked 40 on the

figure 5, for one of them.

  In this figure, we notice the rivet 13 (a few millimeters in diameter) inserted inside a flexible sheath or catheter 41, (typically with a diameter of the order of 10 to 24 mm) inside which it can be moved, under the pressure of an internal catheter 43 in which extends the rear rod 45 which extends, towards the outside of the patient's body, the

notched area 19 of the rivet.

  To introduce this set, we first form a transcutaneous route and we approach, by extravascular laparoscopy, first the "upstream" area of fixation of the prosthesis, transverse to the vessel

considered.

  In FIG. 5, the external buffer 29 of the

  figure 2. Either this buffer was judged useless, or it was put in place just before.

  If, as is then advised, it is the "upstream" strip 29 from the top of FIG. 1 which, after having been inserted flat inside its introducer catheter, has itself wound up around the planned vascular area, in the manner of a split ring, we can then engage the rivet 13 (pushed

  out of its sheath) through this strip 29 to the sleeve of the prosthesis 1.

  Before drilling the wall of the vessel by the head of the rivet, an internal stay may have been engaged inside the prosthesis 1 to support this prosthesis and therefore at the same time the vessel, in addition to the structure 5 which

already plays this effect.

  Once the rivet is engaged, its slide 21 is advanced until it is sufficiently tightened and ensures the tightness of the fixing. The rod 45 is then broken towards the base of the last notch 19 (it was possible to provide notches forming

embrittlement areas).

  If a suture 47 with a curved needle 49 (see FIG. 6) has been provided in place of the rivets 13, the operations are carried out in a manner

  comparable (laparoscopic introduction via a flexible sheath).

  An operating pliers marked 51 in FIG. 7, which can also be introduced laparoscopically inside a sheath 53, can be used to

  maneuver the needle 49 around the vessel.

  Note that the clamp 51 may also be used for

  facilitate the final break of the rod 45.

  Note also that during the installation of the transvascular fixing means 13 or 47/49, the retention of the prosthesis in place in the vessel can be ensured by the hooks 11 or, if no hook has been provided, by a expansion tank of structure 5, then moved away from the

  level 5a, so as not to obstruct or risk being damaged.

  Once the fixation has been made at the "upstream" end of the aneurysm, the procedure is the same for fixing the prosthesis by

  outside the vessel, at the "downstream" end.

  If the implant has an extension sleeve 39 as in FIG. 4, the conditions for fixing and sealing the end

  "upstream" are as described above.

  At the "downstream" end, on the other hand, as already indicated, it is preferable to carry out local invasive surgery by exposing this "downstream" fixation zone, as described in FR-A-2 748 198 or US 08/672

349 of June 25, 1996.

  The surgeon, after having opened the patient's body locally, anastomoses the distal end 30b of the implant 30, preferably by a surgical suture thread, in order to revascularize the zone (s) in a perfectly sealed and controlled manner vascular (s) located even more

"downstream".

  We know that such a correctly performed surgical suture

  ensures good sealing and effective fixing.

  Whether the watertight fixing was carried out as indicated with reference to FIG. 1 or to FIG. 4, it is paradoxically from there that

  new problems have been discovered.

  Indeed, if the seal is good and that consequently, there can no longer be any noticeable penetration of blood inside the aneurysm,

  he will no longer be under pressure.

  It even happens that it dries up, as it were

"curling up".

  However, this risks causing harmful tensions on the vessel,

  in particular at the places of fixation of the prosthesis.

  This is why the aforementioned complementary "transvacular" means 13 and / or 43/47 have been provided, in

  complement or replace the "traditional" square brackets 11.

  Indeed, these complementary means provide a more intimate and less punctual fixation between the prosthesis and the vessel. The fixation is

  stronger and can help control the deformation of the aneurysm.

  But this has a counterpart, namely that the tensions linked in particular to the variation in length of the vessel following its "drying out" cannot be absorbed by a relative displacement

  axial of the prosthesis at the location of its fixing means.

  The solution of the invention for nevertheless "absorbing" these constraints consists in authorizing the prosthesis to vary in length (as well as, if necessary, indirectly in shape, by offset or variation in

  curvature), while leaving it firmly secured.

  However, this variation in length, in particular axial, must also be well controlled, since any bending effect must be avoided, all the more if an offset and / or curvature effect is combined with a

  variation in length (shortening, in particular).

  The invention has planned to face these problems by equipping the

  prosthesis of fractional zones of absorption of its variations in length.

  In this regard, a first solution consists in separating axially from a distance d (see FIG. 1) two successive levels 5a, 5b, 5c, ..., of stent, so that at these locations, the connection between the affected levels of stent is only done through sleeve 3 at which they

are linked.

  Each distance d can be about one to ten millimeters.

  Having thus set aside, neither too much, nor too little, two to many

  groups of floors, we will allow the prosthesis to vary in length.

  Thus, if two opposite forces are applied towards the ends 1a, 1b, of the prosthesis (force F1 and F2 in FIG. 1, for example), the levels of stent concerned will approach each other, the prosthesis still remaining fixed

to the vessel at its ends.

  This axial spacing d is found in Figure 8 which has the sole purpose of showing that some of the stages of the prosthesis frame can be double, such as 5a1, 5a2 where the two levels of corrugated stent are interconnected. Indeed, each level is made up of several metallic wires and these wires change floors, as shown schematically in 55, 57, and as described

in FR-A-2 737 404.

  Of course, the absorption zones of extra length (_) will be

  then located between two sets of multilevel stents.

  To facilitate the desired axial movement, a slightly loose and correctly oriented fixation at the location of the sutures 7 may be useful, at least at certain stent levels, thus allowing a clearance

axial between the sheath and the armature.

  In connection with the sheath extension 39 in FIG. 4, it can also be provided, as illustrated in FIG. 9, that several groups of two adjacent beads such as 61, 63 or 65, 67 are separated by an intermediate zone ( respectively 69, 71) intended to work in

  shortening, and not lengthening like the aforementioned beads.

  Always to avoid concentrating the shortening zones, these zones such as 69, 71, will be distributed axially in several places, each

  of limited length (maximum 8 to 10 mm).

  One could in particular use accordion bellows at least for some naturally axially open and having a capacity

  natural to crash into themselves.

  From the above, it will be understood that the main idea of the invention is very particularly to combine: - a solid fixation which ensures the immobilization of the prosthesis both at its "upstream" end and at its "downstream end" ", - a" perfect "seal at these same two ends, - and, to compensate for this" intimate connection "of the prosthesis / vessel, a capacity for varying the curvature and / or shortening the prosthesis between its" fixed "ends, dividing

  the useful length in several places along the sheath.

  It should also be noted that the invention applies equally to "straight" or "bifurcated" prostheses (in the shape of "Y").

  In Figure 10, there is shown an alternative embodiment

290 of the ring 29 of FIG. 1.

  In this variant, the envelope 291 (for example in Dacron, registered trademark, or in biocompatible suturable material) which coats the curved internal frame 293, is extended, at the location of the slot 295 of this frame (which gives it the appearance of a split ring) by an envelope extension located at one end of the structure 293, or both

  ends, as in the present case (references 291a and 291b).

  In this way, it will be easier to adapt the element 290

  to the diameter of the vessel, under the desired sealing conditions.

  In particular, it will be possible to suture the covering 291 all along the frame 293 and the surgeon will be able to finish the suturing at the locations of the extensions 291a, 291b, which he can if necessary cut to length, if they

are too long (before installation).

  To facilitate the structure, it will be noted that the “C” -shaped frame 293 (for example made of silicone) will only occupy part of the height h of the covering 291, so that the surgeon can suture the ring

  around the vessel, via suturable covering 291,

above or below the frame.

  Of course, like what has been indicated for the ring 29 in FIG. 1, that 290 in FIG. 10 is elastically deformable flat so that it can be introduced by laparoscopy, without having to strip the portion

  upstream of the vessel around which the ring is to be placed.

  The coating 291 could also, alternatively, be made of breakable materials which more or less tend to adhere to the vessel,

  as described with reference to FIG. 13 in FR 97 16625.

Claims (8)

  1. A medical device for treating at least one vascular aneurysm having an upstream end and a downstream end, comprising: - an aneurysmal prosthesis (1, 30) adapted to be introduced into the vessel (23) up to the location of the (aneurysm (s) and comprising a flexible sleeve (3) for channeling the blood therein and a structure in stent (s) (5) linked to the sleeve, the prosthesis having an axis (9) and a length along this axis, - as well as fixing means (11, 19, 47) and sealing means (29, 29a, 31) linked from manufacture to the prosthesis or adapted to be subsequently linked to it to fix the flexible sleeve to the internal wall of the vessel, in a blood-tight manner, towards said upstream and downstream ends of the aneurysm (s), characterized in that the prosthesis has fractionated zones (d, 69, 71) of absorption of a variation of its length so that it absorbs the axial stress created by a drier is lying   aneurysm (s), following the seal obtained.   2. Device according to claim 1, characterized in that the fixing means comprise: - means (13, 47) adapted to pass entirely through the wall of the vessel, - and means (41, 53) for laparoscopic introduction extravascular of said fixing means for positioning them through   the vessel to be treated, from outside this vessel.   3. Device according to claim 1 or claim 2, characterized in that the fixing means comprise rivets (13)   and / or surgical suturing means (47, 49).   4. Device according to any one of the claims   above, characterized in that the sealing means comprise a buffer (s) (29, 29a) to be disposed around only part of the periphery of the vessel to be treated towards the upstream end (23a, 23b) (and towards   the downstream end) of the aneurysm.   5. Device according to claim 4, characterized in that the buffer (s) (290) is (are) like a split ring comprising a structure (293) elastically deformable wrapped in a coating (291) which is suitable for being let through by the fixing means, in particular the sutures, and which extends said structure at the place of the slot (295).   6. Device according to any one of claims   previous, characterized in that the sealing means comprise at least one inner lining (31) linked from manufacture to the prosthesis, at least towards its upstream end, said lining peripherally surrounding the sheath (3) at this end.   7. Device according to any one of the claims   previous, characterized in that the divided areas of absorption of variations in the axial length of the prosthesis comprise accordion bellows (69, 71) formed on the sleeve and adapted to work in shortening.   8. Device according to any one of claims   above, characterized in that: - the stent structure (s) is distributed over several levels (5a, b, ...), along the axis (9) of the prosthesis, at least some of these levels being independent two two, - and the divided areas are, at least for some, defined by a space (d) established axially between two levels of stent (s) successive independent.