Abstract:
The invention concerns an assembly comprising a valve prosthesis to be implanted and a support receiving said valve. The support comprises: at least a tubular portion made of a pliable material slightly stretchable in the circumferential direction; means for fixing said tubular portion to the wall of the corporeal duct; and a plurality of elongated reinforcing elements, arranged on the circumference of said tubular portion and linked to said tubular portion independently of one another; the valve is linked at least partly to said elongated reinforcing elements, in particular at the commissures of its leaflets, and said elongated reinforcing elements jointly form, in extended position, a structure having a predetermined diameter that ensures sufficient extension of said valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   The present application is the U.S. national phase under §371 of International Application No. PCT/FR02/02745, filed on Jul. 31, 2002, which was published in a language other than English and which claimed priority from French Application No. 01/10281, filed on Jul. 30, 2001. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an assembly for setting a valve prosthesis in a corporeal duct, especially a cardiac valve and in particular an aortic valve. 
   2. Description of the Related Art 
   Documents WO 91/17720, WO 98/29057 and EP 1 057 460 each describe an assembly of this type, comprising the valve prosthesis to implant; a radially expandable reinforcement, called a “stent,” clean, in the expanded state, to bear against the wall of the target corporeal duct, this bearing allowing this stent to be immobilized with respect to this wall; and means for fixing the valve to the stent. Setting of the stent thus allows the valve to be installed in the corporeal duct, eliminating the necessity for outside access and thus for direct surgical intervention. 
   However, this technique may have important disadvantages leading to a risk of damage to the valve by the balloon utilized for expanding the stent, and limiting the expansion force that it is possible to give to the stent. This limitation has an effect on the anchoring of the stent, making a displacement of the assembly possible. This limitation also has an effect on the sealing of the stent at the valvular ring, which is particularly affected when the calcified areas give the valvular ring an irregular form and/or a certain rigidity. Expansion of the balloon may also lead to damage to the corporeal duct, particularly when the duct is in a blood vessel. 
   Furthermore, the target corporeal duct may not present a perfectly circular cross section at the implantation site, particularly when the natural valve is retained and when this valve, or valvular ring, comprises calcified areas. Whatever the degree of expansion of the stent, the circular shape of this stent then may not be suitable for the specific anatomy of the implantation site. A defect in sealing of the implanted valve may then result. Furthermore, the stent presents a certain rigidity, which leads to a rigidity in the implantation catheter. This rigidity may make the advancement of this catheter to the implantation site difficult. 
   Another disadvantage of the prior technique is the direct connection of the leaflets&#39; commissures to the stent. A different than anticipated expansion of the stent, and thus of the valve, results, which may lead to a poor coaptation of the leaflets and thus a defective operation of the valve. The stent must consequently be subjected to a predetermined expansion that prevents, or makes difficult, the adaptation of this stent to the anatomic variability. The prior technique also has the disadvantage of, in cases of aortic valve implantation, inducing a risk of obstruction of the coronary ostia. 
   SUMMARY OF THE INVENTION 
   The present invention aims to remedy one or more of these disadvantages. The assembly that the invention relates to comprises a the valve prosthesis to implant and a valve support, the valve and the support being shaped so that they are able to adopt a position of radial contraction, which allows their insertion into the target corporeal duct with the help of insertion/extension means, and a radial extension position, in which the support is immobilized with respect to the wall of the target corporeal duct. 
   According to the invention, the support comprises at least one tubular portion in a pliable material that is slightly stretchable in the circumferential direction, which presents, in its extension position, a dimension in the circumferential direction substantially corresponding to the dimension in the circumferential direction of the location of the corporeal duct in regards to which this tubular portion must be implanted. The invention further comprises means for fixating this tubular portion to the wall of the corporeal duct, and a plurality of elongated reinforcing elements, arranged on the circumference of said tubular portion and linked to said tubular portion independently of one another, the valve being linked at least partially to these elongated reinforcing elements, in particular at the commissures of its leaflets. The elongated reinforcing elements jointly form, in extended position, a structure having a predetermined diameter that ensures sufficient extension of said valve. 
   The support according to the invention thus is not formed by an expandable stent bearing by friction against the wall of the target corporeal duct but is formed by (i) at least one pliable tubular portion that is slightly stretchable in the circumference, fitted with fixation means at the wall of the corporeal duct, and (ii) an installation structure for the valve, extended by such tubular portion or portions. The latter are only subjected to active extension, achieved in particular by means of one or more inflatable balloons, at the areas equipped with the fixation means; the leaflets of the valve are linked to the elongated reinforcing elements and are thus placed on a portion of the support that does not have to be stimulated by the extension means, so that the risk of deterioration of these leaflets by these extension means is eliminated. 
   The extension of the tubular portion or portions does not require a radial force as great as that necessary for extending a stent, and the slight stretchability of the tubular portions beyond their extension position allows the risk of deterioration of the corporeal duct resulting from the utilization of the inflatable balloons to be eliminated. The pliable structure of the tubular portion or portions furthermore allows them to be perfectly adapted to the specific anatomy of the implantation site, particularly when the site is not circular in its cross section due to the presence of calcified areas. The support has an overall longitudinal rigidity definitely less than that of a stent, which significantly facilitates the advancement of the implantation catheter to the implantation site. 
   The valve may be constructed of a biological tissue or of a synthetic material such as, for example, a polymer. The valve may present a base ring allowing its tight connection, particularly by sutures, to the tubular portion or to one of the tubular portions. The commissures of the leaflets are not linked to an expandable area, and the structure formed by the elongated reinforcing elements assures the sufficient extension of these leaflets. The tubular portion, or a peripheral wall that comprises the valve, may present side openings to allow the blood to flow naturally to the coronary ostia, without risk of stagnation. 
   Preferably, the tubular portion or portions present at least one inflatable peripheral chamber, which may be inflated so that a joint is formed which ensures the sealing between this tubular portion and the wall of the target corporeal duct. The proximal area of the tubular portion, or of the proximal tubular portion in case of a plurality of tubular portions, may present a truncated cone shape suitable for bearing against the wall of the ventricle. The tubular portion or portions may be constituted of a biological or synthetic material, particularly a polymer or a fiber fabric known under the name “dacron.” 
   The fixation means are preferably constituted of anchoring fasteners presenting anchoring prongs. These anchoring prongs are configured to be inserted into the wall of the target corporeal duct at the end of the extension of the tubular portions. These fasteners may be plastically deformed; the means may then be provided for extending the anchoring prongs of these fasteners non-radially, particularly in an oblique orientation or according to a trajectory curve, in order to reinforce the resistance of the anchoring obtained. 
   At least one of these fasteners may be in a shape-retaining material such as the nickel and titanium alloy known under the name “NITINOL.” Such a fastener is preferably configured to adopt before implantation an insertion configuration, in which its anchoring prongs are substantially radially positioned with respect to the tubular portion so that they can be inserted in the wall of the duct, and an anchoring configuration, in which these same anchoring prongs are positioned non-radially and/or are curved in order to ensure the anchoring of the fasteners in the wall of the target corporeal duct. 
   The fixation means may also comprise a biological glue, which may be contained in breakable blisters placed on the radial external surface of the tubular portion or portions. These blisters break when they are crushed between the tubular portion or portions and the wall of the corporeal duct, thus freeing the glue. 
   Each elongated reinforcing element advantageously presents a curved form and is placed with its convex side radially turned toward the inside of the support, so that this support presents, at its median zone, a smaller diameter compared to the diameter that it presents at its axial extremities. This smaller diameter allows any risk of covering the coronary ostia to be eliminated. 
   In an alternative embodiment of the invention, the support comprises two tubular portions, such as that described above, whereby one of the extremities of the elongated reinforcing elements is linked to one of these tubular portions while the other extremity of these elongated reinforcing elements is linked to the other tubular portion. The extension of these two tubular portions ensures a perfect extension of the elongated reinforcing elements. 
   According to another possible embodiment of the invention, the support comprises a single tubular portion extending on the support assembly, to the wall of which are linked the elongated reinforcing elements. This single tubular portion may present the aforementioned side openings with regard to the coronary ostia. 
   According to still another possible embodiment of the invention, the support comprises a single tubular portion, from which the elongated reinforcing elements protrude, on an axial extremity of this tubular portion. This support may in particular allow the implantation of a mitral valve. 
   To be well understood, the invention is again described below with reference to the attached schematic drawing representing, by way of non-limiting indication, a preferred form of embodiment of the assembly, to which the invention relates. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of one embodiment of the present inventive prosthetic valve assembly; 
       FIG. 2  is a schematic cross-sectional view of the valve assembly of  FIG. 1  shown in a delivered but not deployed state; 
       FIG. 3  is a partial schematic view of a portion of the assembly of  FIG. 1  prior to anchoring to an intralumenal wall; 
       FIG. 4  is a schematic cross-sectional view of the present inventive prosthetic valve assembly of  FIG. 2  shown in a partially deployed state; 
       FIG. 5  is a partial schematic view of a portion of the assembly of  FIG. 3  after anchoring to an intralumenal wall; 
       FIG. 6  is a schematic view of the assembly of  FIG. 1  shown implanted; 
       FIG. 7  is a schematic view of an alternative embodiment of the present valve assembly; 
       FIG. 8  is a schematic view of yet another alternative embodiment of the present valve assembly; 
       FIGS. 9A ,  10 A,  11 A,  12 A,  13 A and  14 A are schematic cross-sectional views of a portion of the assembly with varying embodiments of fastener before the fastener is placed in the anchoring position; 
       FIGS. 9B ,  10 B,  11 B,  12 B,  13 B and  14 B are views corresponding respectively to the  FIGS. 9A ,  10 A,  11 A,  12 A,  13 A and  14 A, after the fastener is in the anchoring position; 
       FIG. 13C  is a cross sectional view of the assembly of  FIG. 13B  taken across line XIIIC-XIIIC; 
       FIG. 15  is a schematic perspective view of another embodiment of a fastener; 
       FIG. 16  a schematic perspective view of yet another embodiment of a fastener; 
       FIG. 17  a schematic perspective view of yet another embodiment of a fastener; 
       FIG. 18  is a schematic cross-sectional view of a portion of an alternative embodiment of the present inventive assembly showing extendable arms in the course of implanting the assembly; 
       FIG. 19  is a schematic cross-sectional view of a portion of the embodiment of  FIG. 18  showing the extendable arms fully extended; 
       FIG. 20  is a cross sectional view of the assembly of  FIG. 19  taken across line XX-XX; 
       FIG. 21  is a schematic cross-sectional view of an alternative embodiment of the present invention; 
       FIG. 22  is a schematic cross-sectional view of yet another alternative embodiment of the present invention; 
       FIG. 23  is a schematic view of one embodiment of the present inventive assembly shown applied to the mitral valve. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , the present invention comprises a prosthetic valve assembly  1 . The assembly  1  comprises a support  2  on which is mounted a valve prosthesis  3 , which in one embodiment is an aortic valve. The support  2  preferably comprises a distal and proximal tubular portion  4  separated by a plurality of elongated reinforcing elements  5 . The tubular portions  4  are preferably made of a pliable material that is slightly stretchable in the circumferential direction of these tubular portions  4 . In particular, the tubular portions may be constructed of a polymer or of a fiber fabric known under the name “dacron,” or even in a biological tissue like the pericardium. The diameter of these tubular portions  4  should preferably correspond to the diameter of the target native lumen, for example, the aorta, as shown in  FIGS. 2 and 4 , where the native valve ring  101 , the wall  102  of the aorta, and the coronary ostia  103 , are shown. 
   Each elongated reinforcing element  5  is constructed of a relatively rigid material, particularly of a metallic material. The element presents a preferably elongated curve portion  5   a  and two pallets  5   b  at distal and proximal ends, wherein the pallets provide a means to link the reinforcing elements to the respective tubular portions  4 . As shown in  FIG. 1 , these elements  5  are regularly distributed on the periphery of the tubular portions  4  and are placed with their convex side turned radially toward the inside of the support  2 . The latter thus presents, at its median zone, a smaller diameter than that which it presents at its axial extremities. Other configurations are contemplated for the reinforcing elements. 
   Each pallet  5   b  is integrated to the corresponding tubular portion  4  and is fixed to the latter preferably by sutures, although other means are possible. The pallets further comprise a plurality of radially spaced holes in axial pairs of at least two through which pairs the side anchoring prongs of fasteners  6  may project. As shown in  FIGS. 1 and 3 , these side prongs are recessed, before implantation, in the radially spaced holes so that the fasteners  6  do not protrude outside of the outer radial surface of the tubular portion  4 . These holes are preferably sized to retain the fasteners  6  by friction. The prongs of the fasteners  6  are preferably moved into an anchoring position, as shown in  FIGS. 5 and 6 , when an inflatable balloon or other means pushes the fasteners  6  from the interior of the prosthesis assembly  1 . 
   The valve  3  is not in itself part of the present invention and is, thus, not described in great detail. The valve may be constructed of a biological tissue or of a synthetic material, particularly a polymer, and presents a base ring linked to a proximal tubular portion  4  particularly by suturing and leaflets whose commissures  3   a  are linked to the adjacent portions  5   a  of the elements  5 . The connection of the base ring to the proximal portion  4  ensures the sealing of the valve  3  between this ring and this tubular portion, and the connection of the commissures  3   a  to the elements  5  allows the extension of the leaflets when the extension of the support  2  is achieved. 
   Referring to  FIG. 2 , the assembly  1  is configured to be delivered to the target location via a positioning and extension instrument  10 . In the preferred embodiment, the instrument  10  comprises a blood flow catheter  11 , a plurality of expansion means, such as balloons  12 ,  13 ,  14 , and a sheath  9  for maintaining the portions  4  and the elements  5  of the valve prosthesis  1  in a contraction position. The catheter  11  comprises a distal opening  1  la permitting blood flow past the assembly  1  during implantation thereof. The catheter  11  may further comprise a pump facilitating this blood flow. 
   Referring to  FIG. 4 , in the preferred embodiment, the distal balloon  12  is in a truncated cone shape and is dimensioned for bearing against the flared wall  104  of the ventricle when it is inflated. Once inflated to engage the native lumen  104 , the distal balloon  12  sealingly bears against the wall  104  so as to channel the ongoing flow of blood inside the catheter  11 . In the case of the delivery device, the term distal shall refer to the end of the catheter distal from the clinician. In the case of the prosthesis, the term distal shall refer to the end farthest from the ventricle in the direction of blood flow. When positioned properly, the medial balloon  13  is configured to inflate relative to the base ring of the valve  3 , pushing the proximal tubular portion  4  and the prosthesis base ring against the native valve annulus. The proximal balloon  14  of catheter  11  is configured to inflate relative to the distal tubular portion  4  of the prosthesis assembly  1 . 
   Still referring to  FIG. 4 , the sheath  9  is configured to slide on the catheter  11  and can be withdrawn to permit expansion of the assembly  1  to expand into place. As shown, the medial balloon  13  is preferably inflated while the proximal tubular portion  4  is still housed within sheath  9 . The balloon  13  is inflated until the portion  4  presses against the ring  101  and then rests against the median prongs of the fasteners  6  in order to make the fasteners  6  slide through the holes of the pallets  5   b , thus inserting the side prongs of these fasteners  6  in this ring  101 . 
   Once the anchoring of the proximal tubular portion  4  has been achieved, the sheath  9  is moved back so that the distal tubular portion  4 , which is extended and anchored by means of the proximal balloon  14 , can be deployed in the same manner. The expansion of the tubular portions  4  ensures expansion of the elements  5  and the valve  3  accordingly. The pliable structure of the portions  4  allows the latter to be adapted to the specific anatomy of the implantation site, particularly when the natural valve is not excised and/or when this valve or ring  101  presents calcified areas. The elements  5  allow the sufficient extension of the leaflets to be ensured, whatever the configuration of the tubular portions  4 , following implantation. The space between individual elements  5  permit significant blood flow to the coronary ostia  103 . Fasteners  6  ensure immobilization of assembly  1  at the implantation site and preclude migration. The fully implanted assembly  1  is shown in  FIG. 6 . 
     FIG. 7  shows an assembly  1  in which the valve  3  presents a peripheral wall  3   b . This wall  3   b  is connected to the elements  5  and presents side openings  18 , arranged between the leaflets, which allows the blood to flow to the coronary ostia  103 .  FIG. 8  shows an assembly  1  in which the proximal zone  4   a  of the proximal tubular portion  4  presents, or adopts by elastic deformation, a truncated cone shape suitable for bearing against the wall  104  of the ventricle. The balloon  12  causes the extension of this zone  4   a.    
   It is contemplated that the pallets  5   b  and fasteners may comprise one of various configurations, as shown by example in  FIGS. 9A to 17 .  FIGS. 9A to 13C  specifically show the fasteners  6  implementing anchoring by plastic deformation. In one case, the holes of pallet  5   b  may be oriented obliquely, as for example in  FIG. 9A , permitting an oblique extension of the anchoring prongs of the fastener  6 , as shown for example, in  FIG. 9B . Such oblique orientation may reinforce the resistance of the anchoring force. In other alternative arrangements, the median prong of the fasteners  6  may present a non-rectilinear form, either in a chevron configuration (see  FIG. 10A ) or wavy configuration (see  FIG. 11A ). When balloons  13 ,  14  are applied against such configuration, the anchoring prongs engage the native lumen in an oblique orientation, as shown in  FIGS. 10B ,  11 B. Alternatively, the side prongs may be rectilinear (see  FIGS. 9A to 10B ) or curved (see  FIGS. 11A ,  11 B). If desired, the fasteners  6  may be made of a shape-retaining material, particularly the nickel and titanium alloy known under the name “Nitinol.” The anchoring prongs of these fasteners may then be rectilinear before anchoring (see  FIG. 12A ) and may take a curved form by shape retention (see  FIG. 12B ). 
   Referring to  FIGS. 13 and 14 , in other configurations, the fasteners  6  may be axially movable related to the pallet  5   b  by being guided with respect to the pallet to extend the anchoring prongs. This guiding may particularly be performed by engaging one or more fastener bases  6   a  comprising a “T-slot” arranged in the pallet  5   b  (see  FIGS. 13A to 13C ); these anchoring prongs may swivel and may be moved by bearing against the corresponding walls  15  of the pallet  5   b  (see  FIGS. 13A ,  13 B), or may be bendable (see  FIGS. 14A ,  14 B). Movement of these fasteners may be performed by expansion means, such as a balloon with a plurality of chambers inflated successively to axially push the fasteners  6  toward the extension position of their anchoring prongs. 
   Referring to  FIGS. 15 and 16 , the fasteners  6  may comprise a pad  16  and a plurality of perpendicular median prongs promoting a perpendicular compression in the wall. The pads  16  are configured so as to pushed against the native lumen by the expanding force of balloons  13 ,  14 . Referring to  FIG. 17 , the fasteners  6  may be configured so as to be barbed. 
   Referring to  FIGS. 18 to 20 , the proximal balloon  14  may be replaced by radial extendable arms  21 . In this alternative embodiment, the catheter  11  comprises a balloon  23  for extending the elements  5  and an inner sheath  24  linked on its proximal extremity to the catheter  11  but that may slide with respect to the latter outside of this extremity. This sheath  24  comprises longitudinal slots that space the arms  21  apart, and the sheath&#39;s sliding causes the radial extension of arms  21  by elastic deformation. Referring to  FIG. 21 , the distal balloon  12  may also be replaced by a similar structure  25  with radial extendable arms  26  similar to those described in reference to  FIGS. 18 to 20 . As shown in  FIG. 22 , the distal balloon  12  may also be replaced by a structure  35  that extends like an umbrella, the structure  35  comprising, for example, a series of ribs  36  for bearing against the wall  104 . 
   Referring to  FIG. 23 , an assembly  1  comprises a support  2  that itself comprises a single tubular portion  4 , from which the elongated reinforcing elements  5  protrude on an axial extremity of this tubular portion  4 . The latter are rectilinear and of a limited length. In a manner similar to those described above, expansion of the valve  3  may be achieved. 
   The invention provides an assembly allowing the setting of a valve prosthesis in a corporeal duct, especially a cardiac valve and in particular an aortic valve, which presents determinant advantages compared to the homologous assemblies of the prior art. The invention is not limited to the form of embodiment described above by way of example but includes all the variations of embodiment within the scope of the claims below. Thus, for example, the elements  5  may comprise a rectilinear configuration naturally but be constrained during deployment by restraining means to create a medial inwardly curved profile, as shown above. The medial balloon  13  may also be replaced by radial extendable arms. Other proximal positioning means beyond those described herein, such as balloon  12 , arms  25  or ribs  36 , are contemplated. If so desired, the catheter  11  may also comprise a check valve.