Treatment device for a blood circulation vessel

The device includes at least a tubular endoprosthesis (6), deployable between a retracted state and a dilated state, and a hollow support (10) which extends longitudinally between a proximal end (18) and a distal end (16). The support (10) is provided, in the vicinity of the distal end (16), with at least a transverse retention opening. The device includes at least a releasable threadlike tie (12, 14) for holding the endoprosthesis (6) on the support (10). The tie is engaged in the retention opening (28) and actuated from the proximal end (18) of the support (10) to release the endoprosthesis (6). The support (10) includes, over at least a portion of its length, a spring (24) forming the support. The spring (24) has contiguous turns over at least a portion of its length.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a treatment device for a blood circulation vessel of the type comprising:

at least a tubular endoprosthesis, deployable between a retracted state and a dilated state;

a hollow support which extends longitudinally between a proximal end and a distal end, said support being provided, in the vicinity of the distal end, with at least a transverse retention opening;

at least a releasable threadlike tie for holding the endoprosthesis on the support, the threadlike tie being engaged in the retention opening and actuated from the proximal end of the support to release the endoprosthesis.

DESCRIPTION OF THE RELATED ART

Document FR-A-2 863 160 describes a treatment device for a blood circulation vessel comprising an auto-expandable tubular endoprosthesis and a support for holding the endoprosthesis in a retracted state for insertion into the blood circulation vessel. Once the support has been inserted as far as the implantation site, the endoprosthesis is released and the support withdrawn.

Moreover the support and the endoprosthesis are surrounded by an insertion sheath facilitating forward movement in the blood circulation vessel.

To push the support axially in the blood network from its proximal end, it must have some rigidity.

However, this rigidity may prove somewhat impractical, particularly when passing the support through curved portions of blood circulation vessels, such as the aortic cross. It is therefore desirable for the device to be flexible.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is therefore to provide a treatment device for a blood circulation vessel which is easy to insert and move forward in the blood network and which can nevertheless pass easily through curved portions.

The invention therefore relates to a device of the above-mentioned type, characterised in that the support comprises, over at least a portion of its length, a spring forming the support, the spring having contiguous turns over at least a portion of its length.

According to particular embodiments, the device comprises one or more of the following features, taken in isolation or in any technically possible combinations:

the spring delimits a cylindrical inner wall and/or a cylindrical outer wall of the support;

two adjacent turns of the spring delimit between them the retention opening;

the support comprises at least a sleeve which is more rigid axially than the spring, the sleeve surrounding the spring opposite the retention opening;

the sleeve delimits a transverse opening for the passage of the threadlike tie, the passage opening extending opposite the retention opening;

at least one of the two adjacent turns extends opposite the passage opening so as to avoid contact of the threadlike tie with the contour of the passage opening when the threadlike tie is under tension;

the sleeve extends longitudinally between a distal end and a proximal end, at least one of the distal end and the proximal end being engaged with contiguous turns of the spring to immobilise the sleeve relative to the spring;

the treatment device comprises a tip for guiding the distal end of the support in the circulation vessel, the guide tip being fixed on the distal end of the support;

the guide tip is threaded on the spring of the support by engagement with the turns of the spring;

the guide tip comprises a flexible distal head and a rigid proximal shank, the proximal shank forming a spiral suitable for threading onto the spring; and

the guide tip comprises a flexible proximal skirt;

The invention also relates to a system for placing an endoprosthesis in a blood circulation vessel, characterised in that it comprises a device as defined above and a sheath for inserting the device into the blood circulation vessel, the sheath surrounding the support and the endoprosthesis and comprising a capsule for placing the endoprosthesis which contains the endoprosthesis, the sheath being moveable axially along the support towards the proximal end to release the endoprosthesis from the sheath.

According to a particular embodiment of the placement system as defined above, the sheath comprises, over at least a portion of its length, a tubular spring with contiguous turns.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1shows a treatment device2for a blood circulation vessel4.

The device2is suitable for the insertion and placement of an implant consisting of a tubular endoprosthesis6in an implantation site P of the blood circulation vessel4.

In a variant, the implant is an endoprosthesis6carrying an obturation valve placed in an inner blood circulation passage defined by the endoprosthesis. The implant in this case is an endovalve.

The tubular endoprosthesis6is auto-expandable, in other words it can be deployed spontaneously from a retracted state in which it has a small diameter to a dilated state in which it has a larger diameter, the dilated state being the rest state.

The device2also comprises a hollow support10on which the endoprosthesis6is mounted coaxially and releasable ties12,14for holding the endoprosthesis6on the support10in the retracted state.

The support10extends longitudinally between a distal end16and a proximal end18.

The endoprosthesis6is arranged in the support10, in the vicinity of the distal end16thereof.

The distal end16is designed to be implanted in the blood circulation vessel4while the proximal end18is designed to remain accessible to the surgeon outside the patient's body.

The support10according to the invention has the feature of consisting, over a portion of its length, of a spring24with turns26. Over substantially the entire length of the spring24, the turns26are contiguous turns26A. Thus over at least a portion of its length, the spring24has contiguous turns26A.

The spring24is deformable by bending in the region of each turn26A between a rest state in which the turns26A are in contact with one another and a state deformed by bending in which at least one of the contiguous turns26A of the spring24is separated from the adjacent turns.

Thus, a spring with contiguous turns is taken to mean a spring of which the turns, in the rest state of the spring, are in contact with one another over the entire circumference of the turns. A spring with contiguous turns defines a continuous tubular wall over the portion of the spring in which the turns are contiguous and in the rest state.

The spring24therefore forms the outer wall27A and the inner wall27B of the support10(seeFIGS. 1 and 2). The support10therefore consists, over at least a portion of its length, of all or part of the spring24.

The walls27A,27B delimit a generally continuous surface and extend axially.

The spring24illustrated is a cylindrical helix. The spring24has a circular cross-section but in a variant may have a non-circular cross-section. Generally, the spring24is tubular.

The cross-section of the turns26is of any suitable type, for example circular.

The spring24extends over the entire distal end portion of the support10, in other words over the portion of the support10designed to be inserted into the patient's body. In a variant, the spring24extends over any suitable length of the support10.

In the rest state, the support10extends axially.

In the deformed state, the support10bends laterally relative to the support10in the rest state.

The spring24has symmetry of revolution providing uniform flexibility in any direction transverse to the support10.

However, in a variant, the spring24is arranged so as to deform under bending in a preferred direction, the turns of the spring24for example being bound by a coating whilst on the opposite generatrix the turns of the spring are free along a generatrix parallel to the axis of the spring. The coating is made of polytetrafluoroethylene (PTFE), for example.

For the passage of the ties12and14, the spring24also has two zones in which at least two adjacent turns26B are spaced, in the rest state of the spring, to delimit between them an opening28known as the retention opening through which the corresponding tie12,14is engaged (seeFIG. 2).

The support10is provided with a sleeve30arranged opposite each opening28to provide axial rigidity for the support10, specifically rigidity in compression and in traction along the longitudinal axis X-X of the support10.

Each sleeve30surrounds the spring24and delimits an opening32for the passage of the corresponding tie12,14. The passage opening32extends opposite the retention opening28.

At least two adjacent spaced turns26B extend opposite the opening32of the corresponding sleeve30.

The tie14passes between the two adjacent spaced turns26B. The tie14is therefore guided by the turns26B to the passage opening32. Once under tension, the corresponding tie12,14therefore slides against the surface of the turns26B and not against the contour of the passage opening32of the sleeve30. Improved sliding of the ties12,14is thereby achieved.

The sleeve30is fixed on the spring24by engagement of the distal and proximal ends thereof with the contiguous turns26A of the spring24.

The sleeve30is therefore provided with a radial lip for example, engaging with the contiguous turns26A.

The ties12,14each form a loop passing round the endoprosthesis6or, as illustrated inFIG. 2, alternately inside and outside the mesh of the endoprosthesis6.

The free end of the tie12,14is held for example by a rod38of which the proximal end is actuated in the region of a proximal branch40of the support10, while the proximal end of the corresponding tie12can be actuated in the region of another proximal branch42of the support10. Reference may be made for example to application FR-A-2 863 160 for an example of an arrangement of the retention means of the endoprosthesis6.

Generally, any retention tie may be used for the endoprosthesis6. It may for example be a tie of which both free ends can be actuated from the proximal end18of the support10.

The spring24is made of any suitable type of material. The stiffness of the spring24is suitable for providing sufficient axial rigidity under traction. The stiffness can be adjusted by the tension of the lasso.

The spring24has a diameter of between 2 mm and 10 mm, for example.

The turns26have a diameter of between 0.2 mm and 1.5 mm, for example.

FIGS. 3 to 5illustrate the device2more particularly in the region of the distal end16of the support10.

As well as the support10, the device2comprises a guide tip46forming the distal end47of the device2.

The guide tip46is suitable for providing atraumatic contact with the blood circulation vessel4and accordingly comprises a flexible head48which is streamlined when moving distally. The head48is in the form of an ogive, for example.

The guide tip46is also provided to guide the distal end16of the support10. It therefore has a very short proximal shank50(FIG. 4) fixed on the support10.

In the example shown, the proximal shank50is flexible. The shank50is spiral shaped so that it can be threaded inside the spring24.

The spring24also has a limit stop54to prevent the guide tip46(seeFIG. 5) from unscrewing at the end of the threading travel.

The limit stop54is formed by the free end of the turns26of the spring24. The free end thus forms a radially projecting rectilinear portion.

As can be seen inFIGS. 3 and 4, the guide tip46also comprises a resilient skirt56surrounding the shank50and the distal end of the spring24and extending the head48towards the proximal end of the tip46. The skirt56therefore has an outer surface contiguous with the edge of the surface of the head48and with the outer surface of the spring24. The skirt56thus facilitates the atraumatic sliding of the device2against the blood circulation vessel4during insertion and withdrawal of the device2.

FIG. 6shows a placement system60comprising the treatment device2. The system60also comprises an insertion sheath62designed to prevent any significant reflux of blood towards the proximal end of the device2and facilitate the insertion and withdrawal of the device2.

The sheath62surrounds the distal portion of the treatment device2, with the exception of the head48and the guide tip46.

The sheath62according to the invention also has the feature of consisting, over at least a portion of its length, of a spring64with contiguous turns of the same type as the spring24of the support10.

The sheath62comprises a placement capsule65and the spring64.

The capsule65surrounds the support10in the region of the endoprosthesis6.

The capsule65is arranged at the distal end of the spring64.

In the example illustrated, the resilient skirt56of the guide tip rests on the circumference of the distal end of the capsule65. The skirt56therefore protects the blood circulation vessel4from penetrative contact by the distal end of the capsule65.

The skirt56can therefore move spontaneously between a radially expanded configuration, seen inFIG. 6, in which it is applied externally round the capsule65and a radially retracted configuration towards the shank50constituting the rest configuration.

The placement capsule65is of any type suitable for being withdrawn before deployment of the endoprosthesis6. In the example shown, it is moved towards the proximal end18. After the endoprosthesis has been moved, the capsule is slid back against the guide tip46, which corresponds to the position of the capsule65shown inFIG. 3. In a variant, the capsule65comprises means for tearing the capsule65longitudinally to completely release the endoprosthesis6.

It should be noted that in the region of its proximal end the sheath62also comprises a sealing component68to provide sealing against blood around the support10. It may be made of foam, for example.

An example of the operation of the placement system60provided with a treatment device2according to the invention is described below.

Initially, the system60is kept in its packaging (not shown), with the endoprosthesis6in the rest state.

Next, the surgeon removes the system from its packaging. He implants a surgical guide (not illustrated) circulating in the blood circulation vessel4from the external insertion point to the implantation zone P in which the tubular endoprosthesis6is to be implanted.

Next the surgeon inserts the system60into the blood circulation vessel4, along the guide thread.

In linear portions of the blood circulation vessel4, the springs24and64of the support10and of the sheath62are in the rest state.

When the surgeon inserts the system60into a bend of the blood circulation vessel4, the springs24and64move from the rest state to the state in which they are deformed by bending, thereby facilitating passage.

When the implantation zone P is reached, the surgeon withdraws the capsule65, by moving the capsule65towards the proximal end18of the support10, to expose the endoprosthesis6.

The surgeon then releases the retaining threads12and14to deploy the endoprosthesis6to the dilated state.

In the dilated state, the endoprosthesis6rests against the blood circulation vessel4.

The surgeon next withdraws the rod38and then the threads12and14through the proximal end of the support10.

After deployment of the endoprosthesis6, said endoprosthesis is in the dilated state.

The surgeon slides the capsule65against the skirt56towards the distal end of the support10inside the endoprosthesis (seeFIG. 3).

Finally, the surgeon withdraws the system60from the patient's body. The treatment device2, which comprises the support10and the tip46, and the insertion sheath62are therefore withdrawn simultaneously. The guide tip46passes inside the endoprosthesis6.

Because of the spring24, the treatment device2according to the invention provides great flexibility about a transverse axis of the support10. The result is that the stresses applied to the curved portions of the blood circulation vessel4are not as great and insertion is therefore atraumatic.

Moreover, because the spring24has contiguous turns, it has good rigidity in axial compression along its longitudinal axis which ensures good forward movement when the proximal end is pushed by the surgeon.

The skirt56provides a continuous contact surface with the vessel4between the outer surface of the head48of the guide tip46and the outer surface of the capsule65.

The sleeves30reinforce the axial rigidity of the support in the region of the retention openings28. In reality, the turns26B of the spring24must be spaced in the region of the openings28for the passage of the retention ties12,14, and without the sleeves, the axial rigidity of the support10under traction and particularly in compression would be diminished.

Threading the tip46on the spring24makes it easier to assemble the device. This type of fixing is also reliable.

The skirt56of the guide tip46makes it easier to slide the device2against the blood circulation vessel4when inserting and withdrawing the device2.

Because of the spring64, the insertion sheath62has the same advantages of rigidity in axial compression and flexibility under bending as the support10.