Abstract:
The invention relates to a kit including a tubular endoprosthesis having an inner surface delimiting a channel with a longitudinal axis. The kit includes a prosthetic valve designed to be implanted in the channel. The valve includes a supporting frame having an outer surface designed to be pressed against the inner surface, and a flexible cover connected to the frame. The inner surface has at least two segments with variable cross-section along the longitudinal axis. The segments form respectively a proximal stop and a distal stop to lock the axial displacement of the outer surface along the inner surface along two opposite directions.

Description:
BACKGROUND OF THE INVENTION 
     I. Technical Field 
     The present invention relates to a kit which is intended to be implanted in a blood vessel, of the type comprising a tubular endoprosthesis which has an inner surface which delimits a channel having a longitudinal axis; and a prosthetic valve which is intended to be implanted in the channel, the valve comprising a carrier reinforcement which has an outer surface which is intended to be pressed against the inner surface of the endoprosthesis, the reinforcement being able to be deformed radially from a folded position for placement to a deployed position for implantation; a flexible shutter which is connected to the reinforcement and which can be deformed between a blocking position in which it is extended transversely and a release position in which it is contracted transversely under the action of the flow moving in the channel. 
     II. Description of Related Art 
     From EP-A-0 850 607, a kit of the above-mentioned type is known which comprises a tubular endoprosthesis and a prosthetic valve which has a deformable carrier reinforcement and a flexible shutter which is fixed to the reinforcement. 
     A kit of this type is intended to be implanted in place of a valve in a blood vessel. 
     Valves of this type are, for example, present in the heart, between the auricles and the ventricles, or at the outlet of the right ventricle and the left ventricle. These valves ensure one-way circulation of the blood flow, preventing blood reflux following the ventricular contraction. 
     In order to carry out a valve replacement, the tubular endoprosthesis provided in the kit is implanted in the portion of the vessel in which the defective valve is located. Then, the prosthetic valve in the folded state thereof is moved into the inner channel delimited by the endoprosthesis and is pressed against this endoprosthesis by inflating a balloon. 
     A device of this type is not entirely satisfactory. The relative positioning of the prosthetic valve relative to the endoprosthesis is approximate and the fixing of the valve in the endoprosthesis is not very secure. 
     SUMMARY OF THE INVENTION 
     An object of the invention is therefore to provide a kit of the above-mentioned type which allows the successive implantation of a tubular endoprosthesis in a human blood vessel, then a prosthetic valve in the endoprosthesis so that the positioning of the prosthetic valve in the endoprosthesis is straightforward and secure. 
     To this end, the invention relates to a kit of the above-mentioned type, characterized in that at least one of the inner and outer surfaces has at least two portions having a variable cross-section along the longitudinal axis, the portions forming a proximal stop and a distal stop, respectively, to block the axial displacement of the outer surface along the inner surface in two opposing directions. 
     The kit according to the invention may comprise one or more of the following features, taken in isolation or according to any technically possible combination, the two portions having a variable cross-section over one of the surfaces form at least a fixing portion which protrudes radially, the fixing portion which protrudes radially being intended to be received in a corresponding hole which is provided in the other one of the surfaces, the other one of the surfaces has at least two portions having a variable cross-section along the longitudinal axis, the portions delimiting, in the other one of the surfaces, a housing for receiving the or each protruding portion, having a shape which complements that of the or each protruding portion, one of the surfaces delimits at least two protruding portions which are spaced-apart along the longitudinal axis, the or each protruding portion delimits two angular stop surfaces in order to block the rotation of the outer surface along the inner surface around the longitudinal axis, one of the surfaces delimits at least two protruding portions which are spaced-apart in an angular manner around the longitudinal axis, the inner surface has two portions which have a variable cross-section and which are connected to each other by means of a support portion which is radially recessed, the support portion having a length which is substantially equal to the length of the outer surface provided on the carrier reinforcement and delimiting, with the portions having a variable cross-section, a housing for receiving the carrier reinforcement, the two portions having a variable cross-section are delimited by two annular contractions which protrude in the channel and the portions having a variable cross-section are radio-opaque. 
     The invention also relates to a tubular endoprosthesis, of the type having an inner surface which delimits a channel having a longitudinal axis, 
     characterized in that the inner surface has at least two portions which have a variable cross-section along the longitudinal axis, the portions forming a proximal stop and a distal stop, respectively, to block the axial displacement in two opposing directions of an outer surface provided on a prosthetic valve which is intended to be implanted on the inner surface in the channel. 
     Finally, the invention relates to a prosthetic valve which is intended to be implanted in a channel of a tubular endoprosthesis, comprising a carrier reinforcement which has an outer surface which is intended to be pressed against the inner surface of the endoprosthesis, the reinforcement being able to be radially deformed from a folded position for placement to a deployed position for implantation, a flexible shutter which is connected to the reinforcement and which can be deformed between a blocking position in which it is extended transversely and a release position in which it is contracted transversely under the action of the flow moving in the channel, characterized in that the outer surface of the carrier reinforcement has at least two portions having a variable cross-section along the longitudinal axis, the portions forming a proximal stop and a distal stop, respectively, to block the axial displacement of the valve relative to the tubular endoprosthesis. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention will be better understood from a reading of the following description, given purely by way of example, and with reference to the appended drawings, in which: 
         FIG. 1  is a plan view of a first kit according to the invention; 
         FIG. 2  is a cross-section of the first kit according to the invention implanted in a blood vessel; 
         FIG. 3  is a view similar to  FIG. 2  of a second kit according to the invention; 
         FIG. 4  is a view similar to  FIG. 2  of a third kit according to the invention; 
         FIG. 5  is a perspective view of a valve of a fourth kit according to the invention; and 
         FIG. 6  is a section along a transverse plane of the fourth kit according to the invention, implanted in a blood vessel. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A first kit according to the invention is illustrated in  FIGS. 1 and 2 . 
       FIG. 1  illustrates the kit  11  before it is implanted in a blood vessel, whilst  FIG. 2  illustrates the kit  11  implanted in a blood vessel  13 . The vessel  13  is, for example, a pulmonary artery which is connected, at the proximal end  15 A thereof, to the outlet of the right ventricle of the heart, in particular of a human being and, at the distal end  15 B thereof, to the lung. 
     As illustrated in  FIG. 1 , the kit  11  comprises a prosthetic valve  17 , an endoprosthesis  19  which is intended to receive the prosthetic valve  17  and means  21  for implanting and removing the prosthetic valve  17  from the endoprosthesis  19 . 
     The kit  11  is, for example, stored in a packaging  23 . 
     As illustrated in  FIG. 2 , the interchangeable prosthetic valve  17  comprises a carrier reinforcement  25  and a deformable shutter  27  which is supported by the reinforcement  25  and which is fixedly joined thereto. The valve  17  generally has a longitudinal axis X-X′. 
     The carrier reinforcement  25  comprises integrated means for the centripetal compression thereof. More precisely, the reinforcement  25  is formed by at least two branches  29 A,  29 B and in particular three which are connected to each other at a first end  31  in order to form a pincer which is resiliently deformable between a deployed position in which the branches are remote from the centre axis X-X′ and a folded position in which the two branches are close to the centre axis X-X′. 
     The two branches  29 A,  29 B are generally symmetrical relative to the centre axis X-X′ which is aligned with the axis of the vessel, after implantation. 
     The length of the branches, measured along the axis X-X′, is between 2 and 4 cm and is preferably equal to 3 cm. 
     Each branch  29 A,  29 B comprises a portion  33 A,  33 B for support on the endoprosthesis  19 . Each support portion  33 A,  33 B is constituted by a rectilinear segment which generally extends along a generating line of the endoprosthesis  19  when the reinforcement  25  is deployed. Each support portion  33 A,  33 B has an outer surface  35 A,  35 B which is supported on the endoprosthesis  19 . 
     The length of the support portions between a proximal edge  36 A and a distal edge  36 B is from 1 to 3 cm and is preferably approximately 2 cm. 
     These support portions  33 A,  33 B are extended by handling portions  37 A,  37 B which converge towards each other as far as the connection point  31 . The handling portions are generally inclined relative to the centre axis X-X′. 
     The handling portions  37 A,  37 B are generally curved and have a centre of curvature which is arranged outside the space delimited between the two branches. In this manner, the portions  37 A,  37 B protrude towards the inner side of the pincer. 
     The shutter  27  is constituted by a flexible pocket  39  which has a distal opening  41  which is generally circular having an axis X-X′, when the pocket  39  is inflated. 
     The pocket  39  has a generally cylindrical skirt  43  which is extended with a generally hemispherical base  45 . The base  45  has a proximal hole  47  having a small diameter relative to the cross-section of the opening  41 . 
     The pocket  39  is produced, for example, from polyurethane or from biological material (bovine pericardium). 
     The height of the skirt  43  is, for example, equal to 4 or 5 mm and is preferably between 2 and 5 mm. 
     The pocket  39  is connected to the support portions  33 A,  33 B by means of adhesive-bonding or any other appropriate means along the length of the generating lines of the skirt  43 . 
     Advantageously, the pocket  39  is connected to the two branches  29 A,  29 B in such a manner that the two half-skirts delimited at one side and the other have lengths which are slightly different. 
     Finally, the base  45  is connected by means of filaments  49  to the handling portions  37 A,  37 B of the two branches of the carrier reinforcement in order to prevent the pocket being turned over by means of invagination. 
     The endoprosthesis  19  is constituted, for example, by a tubular trellis  55  which is embedded in a film  56  which is extendable and liquid-tight, such as an elastomer material. The trellis  55  is constituted by stainless steel which has resilient properties, so that the endoprosthesis  19  is self-expandable. For example, as illustrated in  FIGS. 2-4 , the trellis is a stainless steel mesh embedded within an elastomer film. An endoprosthesis of this type is generally referred to as a “stent”. 
     As known per se, the endoprosthesis is capable of changing shape spontaneously from a compressed state in which it has a small diameter to a dilated state in which it has a larger diameter, this dilated state constituting the rest state thereof. 
     In the implanted state thereof, as illustrated in  FIG. 2 , the endoprosthesis  19  is pressed, owing to its resilience, against the inner surface of the vessel  13 , thus constituting a sheath inside the vessel  13 . 
     The endoprosthesis  19  thus has an inner surface  57  which delimits a channel  58  for circulation of the blood flow, having an axis X-X′. 
     As illustrated in  FIG. 2 , the inner surface  57  of the endoprosthesis  19  comprises a proximal portion  59  which is substantially cylindrical, a hollow central portion  61  having a transverse dimension greater than the transverse dimensions of the proximal portion  59 , and a distal portion  63  which is substantially cylindrical having a cross-section which is equal to the cross-section of the proximal portion  59 . As also shown in  FIG. 2 , the corresponding outer surface  100  of the endoprosthesis  19  comprises a corresponding proximal portion  120 , a central portion  121 , and a distal portion  122 . 
     The central portion  61  is delimited by a proximal shoulder portion  65  and a distal shoulder portion  67  which have a variable cross-section and which are connected to each other by means of an intermediate portion  69  having a constant (uniform) cross-section (diameter). The shoulder portion  65  is produced by means of an external radial deformation of the reinforcement  55 . It has a cross-section which increases in a distal direction. The shoulder portion  65  forms a proximal stop  71  which is intended to co-operate with the proximal edge  36 A of the support portions  33 A,  33 B. 
     The intermediate portion  69  has a cross-section which is substantially constant and greater than the cross-section of the proximal portion  59  and the distal portion  63 . The length of the intermediate portion  69 , taken along the axis X-X′, is substantially equal to the length of the support portions  33 A,  33 B of the valve  17 . 
     The distal shoulder portion  67  has a cross-section which decreases in a distal direction. It forms a distal stop  73  which is intended to co-operate with the distal edge  36 B of the support portions  33 A,  33 B. As clearly shown in  FIG. 2 , each of the shoulder portions  65 ,  67  forms an edge against which the support portions  33 A,  33 B abut to prevent axial displacement of the support portions  33 A,  33 B. 
     The proximal shoulder portion  65  and the distal shoulder portion  67  are further covered with a radio-opaque material which facilitates the detection thereof using X-rays. 
     As illustrated in  FIG. 1 , the implantation and extraction means  21  comprise a catheter  81  having an inner cross-section which is less than the cross-section of the valve  17  in the deployed state thereof and having an outer cross-section which is less than the inner cross-section of the endoprosthesis  19 . 
     The implantation and extraction means  21  also comprises a tool  83  for traction and thrust which is provided with a jaw  85  at the distal end thereof. 
     Before implanting the kit  11  according to the invention in the artery  13 , the surgeon introduces in a known manner, the endoprosthesis  19  in the compressed state thereof as far as the implantation position thereof in the vessel  13 . Then, the endoprosthesis  19  is placed in the dilated state thereof so that the reinforcement  25  is pressed against the vessel  13 . 
     Then, the jaw  85  of the traction tool  83  grips the end  31  of the valve  17 . The valve  17  is then inserted in the catheter  81  by means of traction on the tool  83 . 
     The valve  17  is then in a retracted state. The catheter  81  is introduced into the vessel  13 . It is moved as far as the inner channel  58  of the endoprosthesis  21  to a position substantially facing the proximal portion  59 . 
     The support portions  33 A,  33 B of the valve  17  are extracted from the catheter and the valve  17  is deployed to the deployed state thereof for implantation. The valve  17  is pushed in a distal direction so that the distal edge  26 B of the support portions is introduced into the hollow central portion  61  delimited in the inner surface  50  of the endoprosthesis  21 . 
     When the distal edge  26 B of each support portion  33 A,  33 B reaches the distal portion  67 , it abuts the distal stop  73  which prevents the distal displacement thereof beyond this stop  73 . 
     Furthermore, in this position, the proximal edge  26 A of each support portion  33 A,  33 B is secured against the proximal stop  71 , which prevents the proximal displacement thereof beyond this stop. 
     The valve  17  is therefore solidly fixed in the inner channel  50  of the endoprosthesis  21 . 
     Furthermore, the relative position thereof with respect to the endoprosthesis  21  is determined in a precise manner by the dimensions of the hollow central portion  61 . 
     An implanted prosthetic valve  17  of this type operates in the following manner. Following an expulsion of the right ventricle, when it increases in volume, the blood flow is drawn into the vessel  13  from the end  15 B towards the end  15 A. The blood fills the pocket  39  which presses on the endoprosthesis  14 , as illustrated in  FIG. 2 , thus blocking the organic vessel  13  in a substantially sealed manner. 
     When the blood flows, the hole  47  allows a constant small flow of blood through the pocket  39 , preventing the formation of a clot at the base of the pocket  39  owing to a possible stagnation of blood. 
     In contrast, during a contraction of the right ventricle, the blood flows from the end  15 A towards the end  15 B. The pocket  39  is then urged externally from the base  45 , causing this pocket to become flattened. In this manner, the blood flow is free to circulate in the vessel  13  at one side and the other of the pocket  39 . 
     After implanting a prosthesis of this type, the wall of the organic vessel  13  progressively adheres to the endoprosthesis  19 . On the other hand, the endoprosthesis  19  constitutes a sheath which forms a screen between the prosthetic valve  17  and the wall of the organic vessel  13 , thus preventing an agglomeration of the organic vessel  13  and the prosthetic valve  17 . In this manner, it is possible to withdraw the prosthetic valve  17 . 
     In particular, since the prosthetic valve  17  is provided with means for centripetal compression, it can be returned to the compressed state thereof and evacuated in a transluminal manner. 
     More precisely, in order to withdraw the prosthetic valve  17 , the catheter  81  is introduced through the right auricle and the right ventricle and is arranged facing the end  31  of the carrier reinforcement which is in the form of a pincer. 
     The traction tool  83  is conveyed through the catheter  81 . The jaw  85  grips the end  31  of the pincer. Whilst the open end, designated  87 , of the catheter is in contact with the handling portions  37 A,  37 B, the carrier reinforcement is progressively pulled inside the catheter  81 . By means of a cam effect, the two arms  29 A,  29 B are urged towards each other and the prosthetic valve is progressively moved into the state thereof in which it is urged and introduced into the catheter  81 . The catheter  81  surrounding the prosthetic valve is then withdrawn from the human body. 
     A new catheter which contains a new prosthetic valve is then introduced into the human body and the valve is released by carrying out the operations set out above, in the reverse order. 
     In this second kit  88  according to the invention, illustrated in  FIG. 3 , the intermediate portion  69  has a cross-section which is substantially equal to the cross-section of the proximal portion  59  and the distal portion  63  of the inner surface  57 . 
     The proximal and distal stops  71  and  73  are formed in the surface  67  on proximal and distal annular contractions  89  and  90  which protrude radially inside the channel  58  and form edges against which the support portions  33 A,  33 B abut to prevent axial movement. 
     The operation of this kit  88  is further substantially similar to that of the kit of  FIG. 2 . 
     In the third kit  98  according to the invention, illustrated in  FIG. 4 , the reinforcement of the valve  17  is formed by a resilient tubular metal trellis  99 . The pocket  39  is connected along the open periphery thereof at two or three points to the tubular trellis  99 . 
     The prosthetic valve  17  further comprises a constriction strand  103  which is permanently engaged in the different loops delimited by the trellis  99  along a circumference thereof. The strand  103  is closed in a loop. It is sufficiently long to allow the expansion of the valve  17 . This strand  103  forms means for centripetal compression. The traction on this strand  103 , for example, using a pincer brings about a constriction of the trellis  99  which allows the prosthetic valve  17  to be retracted after it has been engaged in a catheter  81 . 
     Furthermore, the trellis  99  has, on the outer radial surface thereof, two annular strips  105 A,  105 B which are axially spaced-apart along the axis X-X′. 
     Each strip  105 A,  105 B extends in a transverse plane along the periphery of the outer surface of the trellis  99 . Each strip  105 A,  105 B delimits an outer surface which has a portion  107 A having a cross-section which increases in a distal direction along the axis X-X′ and a portion  107 B having a cross-section which decreases in a distal direction along the axis X-X′. The portions  107 A,  107 B form proximal and distal stops, respectively, for blocking the axial movement of the valve  17 . 
     Furthermore, the endoprosthesis  21  comprises two annular recesses  109 A,  109 B which have shapes which substantially complement the annular strips  105 A,  105 B. Each recess  109 A,  109 B forms two front faces  108 A and  108 B which have a variable cross-section along the axis X-X′ in the inner surface  57  of the endoprosthesis  21 . 
     When the valve  17  is implanted in the endoprosthesis  21 , the annular strips  105 A,  105 B are inserted in the corresponding recesses  109 A,  109 B. The stops  107 A and  107 B co-operate axially with the corresponding front faces  108 A and  108 B in order to prevent the axial displacement of the valve  17  relative to the endoprosthesis  21  in two opposing directions along the axis X-X′. 
     In the variant illustrated in  FIGS. 5 and 6 , the outer surface  35  of the valve  17  comprises a plurality of blocking pins  113  which protrude radially outwards. In this example, the blocking pins  113  are arranged in two transverse planes which are axially spaced-apart. Each transverse plane comprises three blocking pins  113  which are distributed angularly about the axis X-X′. 
     The inner surface  50  of the endoprosthesis  21  delimits recesses  115  having shapes which correspond to the blocking pins  113 . As illustrated in  FIG. 6 , each blocking pin  113  delimits two angular stop surfaces  117 A and  117 B which co-operate with two corresponding angular stop front faces  119 A,  119 B which are delimited in the recesses  115 . 
     In this manner, when the valve  17  is implanted in the endoprosthesis  21  and the pins  113  are inserted in the corresponding recesses  115 , the valve  17  is axially blocked in terms of translation relative to the endoprosthesis  21  and blocked angularly around the axis X-X′ relative to the endoprosthesis  21 . 
     In a variant which is not illustrated, the pins  113  are inserted directly into the holes provided between the filaments of the reinforcement of the trellis  99 . The endoprosthesis  19  has a cross-section which is substantially constant along the axis X-X′. 
     Owing to the invention which has been described above, it is therefore possible to provide an implantation kit which allows a prosthetic valve  17  to be fixed in a tubular endoprosthesis  21  in a precise, secure and removable manner using simple and cost-effective means.