Abstract:
This device comprises a hollow support ( 13 ) delimiting, in the vicinity of a distal end ( 19 ), a transverse retention opening ( 23 A). It comprises an endoprosthesis ( 11 ) which can be deployed between a state retracted against the support ( 13 ) and an expanded state. The device comprises a filamentary connection ( 33 A) forming a clamping ring ( 43 ) surrounding the endoprosthesis ( 11 ) and forming a loop ( 45 ) engaged in the support ( 13 ) through the retention opening ( 23 A). The device comprises a retention rod ( 31 A) mounted to be movable in the support ( 13 ). The retention rod ( 31 A) comprises a hook ( 35 ) for retaining the loop ( 45 ). The displacement of the retention rod ( 31 A) from a release position to a retention position brings about the tightening of the clamping ring ( 43 ). 
     Application to the release of endoprostheses in a blood circulation canal.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a device for treating a blood circulation canal, of the type comprising:
       a hollow support delimiting, in the vicinity of a distal end, at least one transverse retention opening;   an endoprosthesis which can be deployed between a state retracted against a lateral surface of the support and an expanded state in which the endoprosthesis can be released from the support;   at least one filamentary connection forming a clamping ring surrounding the endoprosthesis and forming a loop engaged in the support through the retention opening;   the clamping ring being extensible between a configuration for maintaining the endoprosthesis in its retracted state and a configuration for deploying the endoprosthesis; and, for the or each filamentary connection,   a retention rod which is mounted to be movable in the support between a position for retaining the loop and a position for releasing the loop.       
 
         [0007]    Such a device is used for releasing in a blood circulation canal endoprostheses of the type commonly referred to by the term “stent”, or endoprostheses of the endovalve type comprising a stent and a valve secured to the stent. 
       BACKGROUND TO THE INVENTION 
       [0008]    A device of the above-mentioned type is described in EP-A-0 707 462. In that device, an endoprosthesis is mounted coaxially on two hollow supports capable of sliding relative to each other. The endoprosthesis is maintained in its retracted state by means of two filamentary connections surrounding it at its ends. The filamentary connections are passed into distal and proximal retention openings, respectively, provided in the one and the other of the supports, respectively. The connections are engaged around a retention rod in order to keep them in position at their proximal end. 
         [0009]    In order to release the endoprosthesis, the supports are displaced by sliding relative to each other in such a manner that the distance between the retention openings decreases. 
         [0010]    The decrease in this distance brings about the loosening of the filamentary connections and consequently the simultaneous deployment of the two ends of the endoprosthesis. 
         [0011]    When the positioning of the endoprosthesis in the blood circulation canal is satisfactory, the rod for retaining the filamentary connections is removed from the device. The filamentary connections are then withdrawn from the supports and removed from the patient&#39;s body by causing them to slide in the supports. 
         [0012]    Bearing in mind the great length of the filamentary connections, and their winding path in the supports, the risk of the filamentary connections becoming jammed or breaking during their withdrawal is high. The reliability of the device is therefore reduced. 
       SUMMARY OF THE INVENTION 
       [0013]    The object of the invention is therefore to propose a device for treating a blood circulation canal, which device can be positioned in a precise manner in the vessel while being simple and reliable to use. 
         [0014]    To that end, the invention relates to a treatment device of the above-mentioned type, wherein the retention rod comprises at least one hook for retaining the loop, the displacement of the retention rod from its release position to its retention position bringing about the tightening of the clamping ring from its configuration for deploying the endoprosthesis to its configuration for maintaining the endoprosthesis. 
         [0015]    The device according to the invention may comprise one or more of the following features, taken in isolation or in accordance with any technically possible combination:
       the hook is placed at a distal end of the retention rod;   the hook delimits, on the retention rod, a distal section of non-zero length and a proximal section, the hook projecting transversely relative to the distal section and to the proximal section;   the endoprosthesis delimits, for the or for each filamentary connection, a guide passage for the filamentary connection, the ends of the clamping ring being engaged in the guide passage;   the or each filamentary connection is a strand which is closed on itself, the loop being formed by an extension of the clamping ring extending from the guide passage between the ends of the clamping ring;   the or each filamentary connection is mounted permanently on the endoprosthesis;   the support delimits a proximal retention opening and a distal retention opening, the device comprising, for each retention opening, a separate retention rod comprising a retention hook;   the support delimits a proximal retention opening and a distal retention opening, the device comprising a common retention rod comprising a distal hook and a proximal hook;   the endoprosthesis is mounted coaxially on the support;   the or each filamentary connection is releasable from the endoprosthesis, the retention rod comprising means for retaining at least one retention section of the filamentary connection which is separate from the loop, the section being retained by the retention means when the loop is released from the retention hook, in order to permit the joint displacement of the filamentary connection and the retention rod; and   the retention section of the filamentary connection forms an auxiliary loop engaged in the support through a retention opening, the retention rod comprising an auxiliary hook for retaining the auxiliary loop, which hook opens proximally relative to the hook for retaining the loop.       
 
         [0026]    The invention relates also to a process for preparing a device such as described above, before it is implanted in a blood circulation canal, wherein it comprises the following steps:
       preservation of the endoprosthesis in its expanded state, the or each loop being engaged in a hook of a rod for retaining the loop;   displacement of the retention rod from its release position to the position for retaining the loop, in order to bring about the tightening of the clamping ring and to bring the endoprosthesis into its retracted state.       
 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0029]    The invention will be better understood on reading the following description which is given purely by way of example and with reference to the appended drawings in which: 
           [0030]      FIG. 1  is a front view of a first treatment device according to the invention, the endoprosthesis being maintained in its retracted state; 
           [0031]      FIG. 2  is a sectioned view, taken on the centre transverse plane II-II, of a detail of  FIG. 1 ; 
           [0032]      FIG. 3  is a view analogous to  FIG. 1 , the endoprosthesis being in its expanded state; 
           [0033]      FIG. 4  is a view analogous to  FIG. 2  of the endoprosthesis of  FIG. 3 ; 
           [0034]      FIG. 5  is a three-quarter perspective view, from the front, of the endoprosthesis of the device of  FIG. 1  in its expanded state; 
           [0035]      FIG. 6  is a view analogous to  FIG. 2  of a detail of a second treatment device according to the invention; 
           [0036]      FIG. 7  is a view analogous to  FIG. 6  of a third device according to the invention; 
           [0037]      FIG. 8  is a view analogous to  FIG. 6  of a fourth device according to the invention, the endoprosthesis not being shown; and 
           [0038]      FIG. 9  is a view analogous to  FIG. 5  of the endoprosthesis of the device of  FIG. 8 . 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0039]    The treatment device shown in  FIGS. 1 to 5  comprises a tubular endoprosthesis  11  which has an axis X-X′ and which is mounted coaxially on a single support  13  and is connected to that support  13  by releasable retention means. 
         [0040]    The endoprosthesis  11  comprises a tubular trellis of stainless steel which has spring-like properties. Thus, this endoprosthesis expands automatically. 
         [0041]    The endoprosthesis  11  is, for example, produced by braiding a single thread of a super-resilient material, as described in European Patent Application EP-A-O  857   471 . 
         [0042]    The trellis of the endoprosthesis  11  defines, in the vicinity of a distal end  15  of the endoprosthesis  11 , a distal guide passage  16 A for the retention means, and, in the vicinity of a proximal end  17  of the endoprosthesis  11 , a proximal guide passage  17 A for the retention means. 
         [0043]    As illustrated by  FIG. 5 , each guide passage  16 A,  17 A is delimited by a mesh of the endoprosthesis trellis. The passages  16 A,  17 A are located on the same longitudinal generatrix of the endoprosthesis  11 . 
         [0044]    The trellis has, at the ends  15 ,  17  of the endoprosthesis  11 , folded threads forming bends. 
         [0045]    The endoprosthesis  11  delimits internally a blood circulation canal  18  having an axis X-X′. 
         [0046]    In a variant, the passages  16 A,  17 A are delimited by annuli which are fixedly joined to the trellis and which are located in the canal  18 . 
         [0047]    As known per se, the endoprosthesis  11  is capable of changing shape spontaneously from a retracted state in which it has a small diameter ( FIG. 1 ) into an expanded state in which it has a larger diameter ( FIG. 5 ), this expanded state constituting its resting state. 
         [0048]    In the example illustrated in  FIGS. 1 and 2 , the support  13  comprises a hollow flexible metal tube having an axis X-X′. The inside diameter of the tube is suitable for enabling the tube to be threaded onto a filamentary surgical guide (not shown) installed in the patient, before the endoprosthesis  11  is put in place in a blood circulation canal of this patient. 
         [0049]    The support  13  extends longitudinally in a single piece between a distal end  19  which is to be implanted in the blood circulation canal and a proximal end  21  which is to be accessible to a surgeon. The proximal end  21  is located at a distance from the endoprosthesis  11 . 
         [0050]    Distal and proximal retention openings  23 A and  23 B, which are offset longitudinally, are provided laterally in the support  13 , in the vicinity of the distal end  19  of the support  13 . 
         [0051]    In this example, the openings  23 A and  23 B are provided on the same side relative to a centre longitudinal plane of the support  13 . The distance separating the distal retention opening  23 A from the proximal retention opening  23 B is substantially equal to the length of the endoprosthesis  11  in its retracted state, viewed in a longitudinal direction. 
         [0052]    At its proximal end  21 , the support  13  delimits a control passage  25  which is closed selectively by means  27  for locking the retention means in position. 
         [0053]    The retention means of the endoprosthesis  11  comprise a distal retention rod  31 A and a proximal retention rod  31 B which are associated with a distal retention thread  33 A and a proximal retention thread  33 B, respectively. 
         [0054]    The distal retention rod  31 A and the proximal retention rod  31 B have similar structures. Likewise, the distal retention thread  33 A and the proximal retention thread  33 B have similar structures. Consequently, only the distal retention thread  33 A and the distal retention rod  31 A will be described hereinafter. 
         [0055]    The retention rod  31 A is located in the support  13 . The length of the rod  31 A is greater than or equal to the distance between the distal retention opening  23 A and the proximal end  21  of the support  13 . 
         [0056]    As illustrated in  FIG. 2 , the rod  31 A comprises an end hook  35 , an actuating portion  37 , and a control section  39  which projects through the control passage  25  at the proximal end  21  of the support  13 . The retention rod  31 A thus has the general shape of a crook. 
         [0057]    The end hook  35  is located at the distal end of the actuating portion  37 . It projects laterally relative to the actuating portion  37  towards the distal retention opening  23 A. 
         [0058]    The actuating portion  37  is produced on the basis of a flexible metal rod. It extends in the support  13 . 
         [0059]    The control section  39  extends the actuating portion  37  outside the support  13 , through the control passage  25 . 
         [0060]    The rod  31 A is movable in translation along the axis X-X′ of the support  13 , between a distal position shown in  FIG. 4  for releasing the retention thread  33 A and a proximal position shown in  FIG. 2  for traction on the retention thread  33 A. 
         [0061]    In the distal release position, the hook  35  extends substantially opposite the distal retention opening  23 A. In that position, the control section  39  has a minimum length. 
         [0062]    In the proximal traction position, the hook  35  is located between the proximal retention opening  23 B and the distal retention opening  23 A. The length of the control section  39  is therefore at a maximum. 
         [0063]    In the example shown in  FIGS. 1 to 5 , the distal retention thread  33 A comprises a single strand of pliable material closed on itself. The distal retention thread  33 A thus forms a clamping ring  43  located outside the support  13  in order to surround the endoprosthesis  11 , and a loop  45  engaged in the support  13  through the distal retention opening  23 A. 
         [0064]    The distal retention thread  33 A is mounted permanently on the endoprosthesis  11 . 
         [0065]    The clamping ring  43  surrounds the endoprosthesis  11  outside the trellis, in accordance with a circumference around the axis X-X′. It extends between a first end and a second end which are engaged in the proximal guide passage  16 A and which are connected to the loop  45 . 
         [0066]    In a variant, the clamping ring  43  is engaged in the trellis of the endoprosthesis  11 , in accordance with a circumference, by passing in succession to the inside and to the outside of the trellis. 
         [0067]    The loop  45  extends in the support  13  by connecting the two ends of the clamping ring  43  through the retention opening  23 A. The loop  45  is engaged in the hook  35  of the retention rod  31 A. 
         [0068]    The clamping ring  43  is extensible between a configuration for maintaining the endoprosthesis  11  in its retracted state and a configuration for deploying the endoprosthesis  11 . 
         [0069]    In the configuration for maintaining shown in  FIG. 2 , the diameter of the clamping ring  43  is at a minimum, while the length of the loop  45  in the support  13  is at a maximum. 
         [0070]    Conversely, as shown in  FIG. 4 , when the clamping ring  43  occupies its deployment configuration, its diameter is at a maximum, while the length of the loop  45  in the support  13  is at a minimum. 
         [0071]    When the clamping ring  43  occupies its configuration for maintaining the endoprosthesis  11 , the endoprosthesis  11  is maintained in its retracted state against the support  13 , along a peripheral lateral surface of the support  13 . Conversely, when the clamping ring  43  occupies its deployment configuration, the endoprosthesis  11  is free to occupy its expanded state. 
         [0072]    The operation of the first treatment device according to the invention will now be described by way of example. 
         [0073]    In a first stage, the device is preserved in a sterile pack (not shown). 
         [0074]    In the pack, each retention rod  31  substantially occupies its position for releasing the loop  45 , in which position the hook  35  is located opposite a retention opening  23 A,  23 B. 
         [0075]    For each thread  33 A,  33 B, the loop  45  remains engaged in an associated hook  35 , so that the retention rod  31 A,  31 B retains the retention thread  33 A,  33 B. 
         [0076]    The distal and proximal retention threads  33 A and  33 B are engaged around the trellis of the endoprosthesis  11 , so that each clamping ring  43  occupies its deployment configuration. The endoprosthesis  11  is thus maintained in its expanded state. 
         [0077]    In this condition, the mechanical properties of the endoprosthesis  11  are preserved and, in particular, the tubular trellis thereof is embedded in an extensible and leak-tight film, such as an elastomer. 
         [0078]    In a second stage, the surgeon implants a surgical guide (not shown) which moves in the blood circulation canal or the vein from the external point of introduction as far as the region of the vein or the artery into which the tubular endoprosthesis  11  is to be implanted. 
         [0079]    The surgeon then removes the device from its pack with a view to implanting the endoprosthesis  11  in the blood circulation canal or the vein. The surgeon subsequently releases the means  27  for locking the rods  31 A,  31 B and pulls on the control sections  39  of the retention rods  31 A,  31 B in order to increase the length of those sections  39 . 
         [0080]    During this displacement, each hook  35  is displaced towards the proximal end  21  of the support  13  until the retention rods  31 A,  31 B occupy their position for retaining the loop. 
         [0081]    During this displacement, each retention rod  31 A,  31 B pulls on a corresponding retention thread  33 A,  33 B. The length of each loop  45  increases and the diameter of the clamping rings  43  decreases in a corresponding manner. The endoprosthesis  11  thus passes from its expanded state to its retracted state against a peripheral lateral surface of the support  13 , in which state the trellis is substantially resting against the support  13 , around that support  13 . The support  13  is then positioned in the circulation canal  18 . 
         [0082]    The surgeon then activates the means  27  for locking the retention rods  31 A,  31 B in position in order to immobilize the rods  31 A,  31 B relative to the support  13 . 
         [0083]    The endoprosthesis  11  is thus introduced coaxially with the support  13  as far as its place of implantation by displacement along the surgical guide (not shown). 
         [0084]    In some cases, and in order to maintain a minimum radial space requirement, a sheath (not shown) is arranged around the endoprosthesis  11 , before this introduction, and is withdrawn once the introduction has been carried out. 
         [0085]    Once the endoprosthesis  11  has been introduced, the surgeon proceeds with the deployment thereof. 
         [0086]    Depending on the conformation of the blood circulation canal to be treated, he may choose to deploy first the one or the other of the ends  15  and  17  of the endoprosthesis  11 . 
         [0087]    The deployment of the distal end  15  will be described by way of example. 
         [0088]    First of all, the surgeon releases selectively the control section  39  of the distal retention rod  31 A. Then he progressively reduces the length of that section  39  by displacing the rod  31 A towards the distal end  19  of the support  13 , which displaces the hook  35  towards the distal end  19 . 
         [0089]    During this displacement, the length of the loop  45  decreases. The diameter of the clamping ring  43  increases in a corresponding manner, which enables the endoprosthesis  11  to be deployed radially relative to the axis X-X′ of the support  13  at the distal end  15  of the endoprosthesis  11 . The trellis therefore moves away from the support  13  and approaches the walls P of the canal to be treated in order to rest on those walls P. 
         [0090]    If the surgeon is not satisfied with the positioning of the distal end  15  of the endoprosthesis  11  when the latter is deployed, he again actuates the control section  39  by displacing the retention rod  31 A towards the proximal end  21  of the support  13 . This increases the length of the loop  45  and reduces the active length of the clamping ring  43  in order to compress the endoprosthesis  11  against the support  13 . The endoprosthesis  11  is then displaced until it reaches a more satisfactory position. 
         [0091]    In an analogous manner, the surgeon then carries out the deployment of the proximal end  17  of the endoprosthesis  11  by means of the proximal retention thread  33 B. 
         [0092]    In this configuration, the retention rods  31 A,  31 B occupy their position for releasing the loop  45 . The loops  45 , however, remain engaged in the hooks  35 . 
         [0093]    When the surgeon is satisfied with the positioning of the distal end  15  of the endoprosthesis  11 , he displaces the distal retention rod  31 A towards the distal end  19  of the support  13  in order to bring the hook  35  beyond the distal retention opening  23 A until the loop  45  is completely released from the hook  35 . 
         [0094]    The distal end  15  of the endoprosthesis  11  is then secured irreversibly to the walls P of the blood circulation canal. 
         [0095]    The surgeon then proceeds in the same manner with the proximal end  17  of the endoprosthesis  11 . He subsequently removes the support  13  and the retention rods  31 A,  31 B from the patient. The support  13  is then completely released from the endoprosthesis  11 . 
         [0096]    In this device, the length of the retention threads  31 A,  31 B is at a minimum, so that their movement in the support  13  presents a low risk of blocking. 
         [0097]    Consequently, the reliability of the deployment of the endoprosthesis is improved since it is no longer necessary to cause long lengths of thread to move in the support  13 . 
         [0098]    In a variant shown with a dotted line in  FIG. 5 , each loop  45  has an end annulus  101 , which is produced, for example, from a radio-opaque material and which is to be gripped by a hook  35 . 
         [0099]    In the second device according to the invention, which is shown in  FIG. 6 , the hook  35  of each retention rod  31 A,  31 B is not located at the distal end of the rod  31 A,  31 B. 
         [0100]    Thus, each hook  35  delimits on the rod  31 A,  31 B a proximal section  61  and a distal section  63  of non-zero length, which is suitable for retaining the hook  35  in the support  13 . 
         [0101]    The hook  35  projects radially relative to the proximal section  61  and to the distal section  63 . 
         [0102]    When the retention rod  31 A,  31 B is placed in its position for releasing the loop  45 , with the hook  35  located opposite a retention opening  23 A,  23 B, the distal section  63  rests against the internal surface  67  of the support  13 , distally relative to the opening  23 A,  23 B. This prevents the hook  35  from being carried along by the loop  45  out of the support  13  through the retention opening  23 A,  23 B during the deployment of the endoprosthesis  11 . The reliability of the device is further improved. 
         [0103]    In a variant (not shown), the two retention rods  31 A,  31 B are connected mechanically at a point located proximally relative to the proximal retention opening  23 B when the hooks  35  are located opposite the retention openings  23 A,  23 B. 
         [0104]    The third device according to the invention, which is shown in  FIG. 7 , comprises a single retention rod  31  which is provided with a distal retention hook  35 A located at the distal end of the rod  31 , and with a proximal retention hook  35 B which projects relative to the rod  31 . 
         [0105]    The distance separating the distal hook  35 A from the proximal hook  35 B is substantially equal to the distance separating the distal retention opening  23 A from the proximal retention opening  23 B. 
         [0106]    This third device permits the simultaneous deployment of the proximal end  17  and the distal end  15  of the endoprosthesis  11 . 
         [0107]    A fourth device according to the invention is shown in  FIGS. 8 and 9 . This device constitutes a variant of the second treatment device according to the invention. However, unlike the second device, each retention thread  33 A,  33 B is releasable from the endoprosthesis  11 . 
         [0108]    To that end, each retention thread  33 A,  33 B forms a principal loop  45  connected to a first end of the clamping ring  43 , and an auxiliary loop  201  located in the support  13  and connected to a second end of the clamping ring  43 . 
         [0109]    The clamping ring  43  is formed by two adjacent strands of the retention thread  33 A,  33 B. These two strands are folded into a loop at the first end of the clamping ring  43  in order to form the principal loop  45  and are folded into a loop at the second end of the clamping ring  43  in order to form the auxiliary loop  201 . 
         [0110]    The principal loop  45  and the auxiliary loop  201  are connected to the clamping ring  43  through the same retention opening  23 A,  23 B and through the same guide passage  16 A,  17 A. 
         [0111]    Unlike the device shown in  FIG. 6 , each retention rod  31 A,  31 B has at its distal end a clip  203  for retaining the auxiliary loop  201 . 
         [0112]    The clip  203  is formed by a fold  205  in the distal section  63  of the retention rod  31 A,  31 B extending between the distal end of the rod  31 A,  31 B as far as a point located proximally relative to the retention hook  35 . The fold  205  extends in the opposite direction to the hook  35  and the retention opening  23 A,  23 B, relative to the axis of the rod  31 A,  31 B. The clip  203  opens towards the proximal end  21  of the support  13 . 
         [0113]    The auxiliary loop  201  is engaged in the retention clip  203 . 
         [0114]    When the surgeon removes the fourth device from its pack and displaces each retention rod  31 A,  31 B towards the proximal end  21  of the support  13 , the hook  35  and the clip  203  of each rod  31 A,  31 B also move towards that proximal end. 
         [0115]    During this displacement, the loop  45  and the auxiliary loop  201  are pulled in the support  13  towards the proximal end  21 , so that the length of the clamping ring  43  decreases in order to cause the endoprothesis  11  to pass from its expanded state into its retracted state against the support  13 . 
         [0116]    The deployment of the endoprosthesis  11  is then analogous to that of the second treatment device. 
         [0117]    When the endoprosthesis  11  is deployed in position in the blood circulation canal and the surgeon is satisfied with the positioning of this endoprosthesis, he displaces the retention rod  31 A,  31 B towards the distal end  19  of the support  13  in order to bring the hook  35  beyond the corresponding retention opening  23 A,  23 B. The principal loop  45  is then completely released from the hook  35 . 
         [0118]    However, bearing in mind the length of the fold  205 , the auxiliary loop  201  remains engaged in the clip  203 . 
         [0119]    Subsequently, when the surgeon pulls the retention rod  31 A,  31 B towards the proximal end  21  of the support  13 , he also pulls on the corresponding retention thread  33 A,  33 B by way of the auxiliary loop  201  engaged in the clip  203  in order to permit the joint displacement of the retention thread  33 A,  33 B and the retention rod  31 A,  31 B. The retention thread  33 A,  33 B is then completely released from the endoprosthesis  11  and is removed from the patient at the same time as the retention rod  31 A,  31 B.