the treatment device shown in fig1 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 . the endoprosthesis 11 comprises a tubular trellis of stainless steel which has spring - like properties . thus , this endoprosthesis expands automatically . 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 . 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 . as illustrated by fig5 , 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 . the trellis has , at the ends 15 , 17 of the endoprosthesis 11 , folded threads forming bends . the endoprosthesis 11 delimits internally a blood circulation canal 18 having an axis x - x ′. 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 . as known per se , the endoprosthesis 11 is capable of changing shape spontaneously from a retracted state in which it has a small diameter ( fig1 ) into an expanded state in which it has a larger diameter ( fig5 ), this expanded state constituting its resting state . in the example illustrated in fig1 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 . 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 . 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 . 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 . 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 . 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 . 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 . 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 . as illustrated in fig2 , 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 . 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 . the actuating portion 37 is produced on the basis of a flexible metal rod . it extends in the support 13 . the control section 39 extends the actuating portion 37 outside the support 13 , through the control passage 25 . the rod 31 a is movable in translation along the axis x - x ′ of the support 13 , between a distal position shown in fig4 for releasing the retention thread 33 a and a proximal position shown in fig2 for traction on the retention thread 33 a . 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 . 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 . in the example shown in fig1 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 . the distal retention thread 33 a is mounted permanently on the endoprosthesis 11 . 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 . 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 . 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 . 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 . in the configuration for maintaining shown in fig2 , 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 . conversely , as shown in fig4 , 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 . 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 . the operation of the first treatment device according to the invention will now be described by way of example . in a first stage , the device is preserved in a sterile pack ( not shown ). 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 . 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 . 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 . 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 . 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 . 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 . 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 . 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 . 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 . 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 ). 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 . once the endoprosthesis 11 has been introduced , the surgeon proceeds with the deployment thereof . 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 . the deployment of the distal end 15 will be described by way of example . 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 . 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 . 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 . 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 . 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 . 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 . the distal end 15 of the endoprosthesis 11 is then secured irreversibly to the walls p of the blood circulation canal . 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 . 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 . 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 . in a variant shown with a dotted line in fig5 , 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 . in the second device according to the invention , which is shown in fig6 , 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 . 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 . the hook 35 projects radially relative to the proximal section 61 and to the distal section 63 . 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 . 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 . the third device according to the invention , which is shown in fig7 , 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 . 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 . this third device permits the simultaneous deployment of the proximal end 17 and the distal end 15 of the endoprosthesis 11 . a fourth device according to the invention is shown in fig8 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 . 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 . 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 . 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 . unlike the device shown in fig6 , each retention rod 31 a , 31 b has at its distal end a clip 203 for retaining the auxiliary loop 201 . 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 . the auxiliary loop 201 is engaged in the retention clip 203 . 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 . 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 . the deployment of the endoprosthesis 11 is then analogous to that of the second treatment device . 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 . however , bearing in mind the length of the fold 205 , the auxiliary loop 201 remains engaged in the clip 203 . 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 .
this device comprises a hollow support delimiting , in the vicinity of a distal end , a transverse retention opening . it comprises an endoprosthesis which can be deployed between a state retracted against the support and an expanded state . the device comprises a filamentary connection forming a clamping ring surrounding the endoprosthesis and forming a loop engaged in the support through the retention opening . the device comprises a retention rod mounted to be movable in the support . the retention rod comprises a hook for retaining the loop . the displacement of the retention rod from a release position to a retention position brings about the tightening of the clamping ring . application to the release of endoprostheses in a blood circulation canal .