Implant and insertion system for implant

Abstract

Implant (1) having the following features: a. an implant body (2) is expandable from a non-expanded state to an expanded state; b. the implant body (2) is self-expanding; c. it comprises a flexible tensioning means (8) which loops around the implant body (2) with at least one loop in order to hold the implant body (2) in the non-expanded state; d. the loop has a locking crown at one end which is in operative engagement with a locking body (15); e. the locking body (15) is displaceable relative to the locking crown in order to release the locking crown and the loop and in order to expand the implant body (2).

Description

[0001] Implant and implant delivery system

[0002] The invention relates to an implant with the features of claim 1 and an insertion system for such an implant with the features of claim 10.

[0003] Self-expanding implants, especially stents, can be held together by an outer tube before implantation and released after placement by retracting the outer tube. Systems with an outer tube are comparatively rigid. The outer tube also results in larger diameters, which makes them more difficult to use in endoscopes compared to systems where the stent is held in a non-expanded state by a suture. Retracting the suture requires relatively high forces due to friction within the system, which in turn necessitates a thicker suture with high tensile strength. Suture systems are somewhat more complex to manufacture, as the knotting technique involves manual labor. There is also a certain risk that the suture will tighten and impede stent release. However, this method eliminates the need for an outer tube. Suture systems are also thinner.

[0004] Implant delivery systems should generally be relatively thin and flexible, and especially easy to use. Dislocation of the stent during withdrawal of the outer tube or release of the suture should be avoided. Ideally, even with suture systems, the distance required to release the stent should be as short as possible, namely the length of the loaded stent.

[0005] The invention aims to provide an implant that is primarily inexpensive to manufacture, thin, and flexible. Furthermore, it aims to provide an insertion system for such an implant that is safe to use.

[0006] This problem is solved in the case of an implant with the features of claim 1 and in the case of an insertion system with the features of claim 10.

[0007] The implant according to the invention has an implant body that can be expanded from a non-expanded state to an expanded state. The implant body is self-expanding.

[0008] The implant features a flexible traction element that encircles the implant body with at least one loop to hold it in its non-expanded state. At one end, the loop has a locking recess that engages with a locking element. In this context, engagement means that the locking element touches the locking recess and secures it in such a way that at least one loop of the locking recess cannot be released by the locking element and / or by one or more other sections of the loop as long as the locking element is in position. The locking element blocks a releasable knot in one of the loops. The knot is open when the locking recess is bent open. The locking element is movable relative to the locking recess. If the locking element is moved, it can release the locking recess and thus the loop.The self-expanding implant body can now expand automatically to the expanded state.

[0009] The system according to the invention is based on the fundamental principle that the implant is secured in its unexpanded state by a flexible tensioning element. The flexible tensioning element is, in particular, a wire or a linear textile structure with at least one fiber, especially a thread with multiple fibers. The tensioning element secures the implant body by means of one or more loops that surround the implant body. The loops are held in their initial position by a locking element that has a locking recess.

[0010] The locking element is in particular rod-shaped. It is preferably flexible, although it may have less flexibility than the flexible traction element that is guided around the implant in one or more loops.

[0011] Specifically, the locking element is a wire that passes through or rests against the locking recess. Retracting the locking element releases the locking recess. The loop opens, and the implant body can expand to the desired position and thus be applied.

[0012] The system according to the invention, being an extended thread system, is thinner and more flexible than comparable systems, particularly those with an external sheath. This facilitates the advancement and tracking of the stent's position. A further advantage is that retracting the locking element requires only very low forces, thus preventing dislocation of the implant body during application.

[0013] Another advantage is the system's ease of use, as the locking element only needs to be retracted over a very short distance—just the length of the loaded implant body. This is extremely convenient for the user and allows, for example, the implant to be released by a lever or a lever or slider on a handle of the delivery system. A user accustomed to releasing a stent by retracting an outer tube will find the handling of the thread system as described in the invention to be comparable. The outer tube has been replaced by the combination of the flexible traction element and the locking element. However, the flexible traction element and the locking element require significantly less space in the radial direction of the implant body and are considerably more flexible.

[0014] The insertion system is easier to manufacture than pure thread systems because different knots can be used. It is safer to use because the knots are easier to untie. Friction within the system is reduced. The ends of the loop do not pinch each other undesirably in the area of ​​a knot, preventing the knot from being untied only with increased force. This allows the use of thinner, flexible traction elements, particularly threads. Furthermore, the system according to the invention can be very advantageously used for a rapid-exchange system. Rapid-exchange systems have a lateral opening for a guide wire, not just openings at the proximal and distal ends of the insertion system.

[0015] The release of a suture-secured implant, e.g. a Y-stent, is by no means trivial, as the stent must be spatially aligned during this process and must not be dislodged during release.

[0016] One of the key advantages of the method according to the invention is that the locking element only needs to be displaced over a very limited length to release the entire stent. The risk of displacing the implant in the process is low. Furthermore, release requires very little force. The knotting technique used at the ends of the loop is also crucial in this regard.

[0017] It is considered particularly advantageous if the loop has a locking lug at one end and a retaining lug at the other, with the locking lug passing through the retaining lug. These two lugs can interlock in various ways. The locking lug preferably extends through the retaining lug, thereby preventing the retaining lug from shifting or releasing the other end of the loop. This fixes both ends of the loop to each other. If the locking element is now separated from the locking lug, i.e., taken out of engagement, in particular by being pulled out of the locking lug or pulled out from between the retaining lug and the locking lug, the materially flexible locking lugs and retaining lugs can slide apart and immediately release the implant body circumferentially at the point where a loop was previously positioned.

[0018] Within the scope of the invention, it is also fundamentally possible that the locking element penetrates both the holding bay and the locking bay, or is in contact or effective engagement with both the holding bay and the locking bay simultaneously.

[0019] The term "bay" describes a curve or arc in the flexible traction element. The ends of the arc or curve are called legs. If the legs are closed without crossing, it is an open bay; otherwise, it is a closed bay. If the legs cross, it is an eye. Within the scope of the invention, the bays can be open or closed. The legs are as much a part of the bay as the arc or curve. Therefore, the locking element can also engage via the legs. The bay is the basic shape of various knots that, according to the invention, should be easily released.

[0020] Neither the flexible traction element nor the locking mechanism should remain in the patient's body. Therefore, both the flexible traction element and the locking mechanism are detachably connected to the implant body and are removed from the body after implantation using the delivery system. For longer implants, the traction element can be wrapped around the implant body in multiple loops. These multiple loops can be released by a single locking mechanism, which is operated by removing the locking mechanisms sequentially from distal to proximal, specifically by pulling them out of the locking recesses. The locking mechanism itself is preferably rod-shaped and has limited flexibility.Preferably, the wire possesses the necessary flexural rigidity to securely lock the nodes in the locking recess, yet is thin enough to be easily withdrawn from the locking recesses with minimal static and kinetic friction due to its small surface area. For this purpose, it preferably runs in the implantation direction and thus, in a sense, parallel to the implant body, particularly parallel to the longitudinal axis or outer surface of a stent. The locking element has an actuating end proximal to the delivery system for handling and removal. Such an actuating end can also be provided on the retraction element to remove the flexible retraction element. However, the flexible retraction element can also be rigidly connected to the delivery device, as the latter is retracted after release anyway. The retraction element can be pulled along with the delivery device during this process.

[0021] The implant is, in particular, a tubular stent. It can also be a bifurcated stent comprising a main body and at least one branch. The invention makes it possible to release, i.e., expand, the main body and the branch independently of one another by arranging a second locking element parallel to the locking element of the main body in the region of the at least one branch. In a Y-stent, for example, three different locking elements can be provided to first release the two branches and then the main body. This allows for very precise positioning of the individual branches and even minor positional corrections before the next branch and then the main body are released.

[0022] The implant is preferably guided to the desired position using a guide wire before the implant body is released. To protect against vascular injury, a distal end of the rod-shaped barrier can be slightly bent radially inward. Furthermore, an introduction system for such an implant can provide an implant carrier with a tip at its distal end that projects axially relative to the implant. This tip, which widens radially in diameter proximally, can have a receptacle on its proximal side facing the implant body for a distal end of the barrier and also for the distal end of the stent. The receptacle can be designed to hold the distal end of the barrier within it. The receptacle is, in particular, concave. It is specifically an axially open, circumferential depression, especially when the distal end of the stent is positioned within the receptacle.A circumferential recess is not strictly necessary if only the distal end of the locking element is to be accommodated. In this case, a small bore can serve as the receptacle.

[0023] In Y-shaped stents or stents with branches, each branch can contain a branch of a forked implant carrier. Each of these implant carriers has a tip, specifically for receiving the distal end of a barrier element for the respective branch. The tips can each have the concave recesses described above.

[0024] A significant advantage of the invention is that the force required to release the implant is considerably less than with implants secured solely by flexible traction elements, such as sutures. The combination of a locking element with locking lugs on loops results in an implant arrangement that is easy to manufacture, flexible, slim, and can be applied with exceptionally little force.

[0025] The advantages of the invention arise from the fact that the traction element is flexible and possesses greater flexibility than the locking element. The locking element preferably has a smooth surface, so that the friction between the locking element and the single or multiple points of contact with the traction element is low. The flexible traction element is in particular a thread in the form of a linear textile structure, and the rod-shaped locking element is preferably a wire.

[0026] The invention is explained in more detail below with reference to exemplary embodiments schematically illustrated in the drawings. The drawings show:

[0027] Figure 1 shows a schematic representation of a first embodiment of an insertion system with an implant;

[0028] Figure 2 shows a first embodiment of a node;

[0029] Figure 3 shows a second embodiment of a knot;

[0030] Figure 4 shows a second embodiment of an insertion system for an implant; Figure 5 shows a further embodiment of a node;

[0031] Figure 6 shows another embodiment of a knot;

[0032] Figure 7 shows another embodiment of an insertion system for a Y-stent in a starting position;

[0033] Figure 8 shows the embodiment of Figure 7 in the partially expanded state;

[0034] Figure 9 shows another embodiment of an insertion system with an outer shell and

[0035] Figure 10 shows another embodiment of an insertion system in a rapid-exchange design, in which a guide wire is led out laterally from an implant carrier.

[0036] Figure 1 shows an implant 1 with an implant body 2 attached to an delivery system 3. The implant body 2 is a self-expanding wire stent. It is shown in its unexpanded state. The implant body or stent could also be made of silicone or laser-cut.

[0037] Within the implant body 2 is an implant carrier 4, which has a tip 6 at its end 5 that projects beyond the implant body 2. The tip 6 has a narrow distal end and widens towards its proximal side 7. The implant body 2 is encircled multiple times by a flexible traction element 8 and is held in the non-expanded state. The flexible traction element 8 has several loops 9, 10 arranged axially apart from each other. In this case, there are nine loops. The number of loops is variable and is selected according to the requirements. The first and last loops can be additionally secured with one or more half hitches.

[0038] In this first embodiment, the flexible traction element 8 is guided through a channel 11 of the implant carrier 4. Proximal to an extracorporeal handle 12, the proximal end 13 of the traction element 8 is provided with a securing end 14. Its function is explained below. The implant 1 also has a rod-shaped locking element 15 in the form of a flexible wire, which extends parallel to and outside the implant body 2. A proximal actuating end 16, positioned extracorporeally during use, is guided through the channel 11 of the implant carrier 4 and out through the handle 12. After placement of the implant 2, the locking element 15 can be retracted proximally. This first releases a knot 17 of the distally arranged loop 9, allowing the implant body 2 to expand in this area first.One after the other, all subsequent knots 17 of the further loops are released until finally the most proximal loop 10, or the last loop in this sequence, of the release process is also released. After removal of the locking element 15, the implant body 2 is free of radial resistance and can fully expand as a vascular support within the local tissue structures. The implant body 2 is now in place. The traction element 8 can now be retracted via the actuating end 14 of the traction element 8, and finally the implant carrier 4 can be removed entirely. Alternatively, the traction element 8 is attached to the implant carrier 4 (Figure 4) and is pulled out together with the implant carrier 4.

[0039] Figures 2, 3, 5 and 6 show different embodiments of nodes 17 suitable for the invention.

[0040] Figure 2 shows an enlarged view of the implant body 2 in the form of a stent made of wire mesh. The locking element 15 is a wire that is somewhat thicker than the wire of the stent and runs radially outside the implant body 2 in the axial direction and parallel to the longitudinal direction of the implant body 2. Figure 2 shows a single loop 9 of the flexible traction element 8 on the implant body 2. The loop 9 is wrapped around the implant body 2 on the side facing away from the viewer and holds it in the non-expanded state. The knot 17 faces the viewer. The loop 9 has a locking recess 19 at one of its upper ends 18 in the plane of the image. This recess deflects the loop by approximately 180°, i.e., in the opposite direction of wrapping. The locking recess 19 is penetrated by the locking element 15.For this purpose, one leg of the locking bay 19 engages under the locking body, while the other leg of the locking bay 19 engages over the locking body 15. In this way, the locking bay 19 is fixed in place.

[0041] The loop 9 has a retaining lug 21 at its other end 20, which is oriented in the opposite direction to the locking lug 19. The retaining lug 21 is guided radially outwards over the locking element 15 with both legs and engages the locking lug 19 radially inwards with its arc. This results in a wrap-around. Consequently, the locking lug 19 is located within the retaining lug 21. If the locking lug 19 were not present, the retaining lug 21 would not be held in the position shown. Only the locking element 15, which fixes the locking lug 19, prevents the retaining lug 21 from sliding away from the locking lug 19. The node 17 thus formed is stable as long as a radially outward expansion force is applied by the implant body 2. This force is always present. The implant body 2 exerts constant pressure on the node 17. Release is therefore extremely simple.

[0042] Furthermore, the degree of compression can be influenced by pulling on the flexible tensioning element 8, and an additional radial force can be exerted on the implant body 2. The depicted node 17 is also easy to manufacture.

[0043] In practice, the wire diameter of the rod-shaped barrier element 15, the thread diameter of the linear textile structure or the flexible wire tensioning element, and the choice of knots must be coordinated. The roughness of the barrier element 15 and the type of linear textile structure, e.g., the number of filaments, braided or twisted threads, also play a role.

[0044] Theoretically, it is possible for the locking element itself to be formed by the flexible tensioning element, in the sense that it is a single-thread solution, whereby instead of the locking element being used as a wire, a thread loop of the flexible tensioning element is used, which is pulled back for release. A further advantage of the invention is that during crimping, i.e., when compressing the implant body 2, the knots 17 are initially tied loosely, and by tightening the flexible tensioning element 8, the implant body is crimped as required, whereby the knots 17 are simultaneously tightened and secured by the restoring force of the implant body 2.

[0045] Figure 3 shows another embodiment of a node. For functionally identical components, the reference numerals introduced in Figure 2 will be used in the following, even if the nodes differ in their structure.

[0046] The node 17 in Figure 3 also includes a locking bay 19, which in this case extends upwards in the plane of the image, starting from the lower end. The locking bay 19 is a closed bay and is guided radially outside, i.e., on the outside, over the locking element 15 with both legs. The locking element 15 does not penetrate the locking bay 19, but is nevertheless in contact with it and thus also engages with the locking bay 19. The depicted loop 9 with the locking bay 19 at one end has a retaining bay 21 at its other end 18, which is also a closed bay. The two legs of the retaining bay 21 are guided radially outside, first through the locking bay 19, and then engage under the locking element 15.In the next section, the legs of the retaining bay 21 cross the legs of the locking bay 19 radially on the outside and then form an arc of the retaining bay 18, which engages under the legs of the locking bay 21. Because the locking bay 19 and the retaining bay 21 are so tightly intertwined, the locking element 15 is held very securely. This node has a significantly higher strength than the node 17 of Figure 2 and could, for example, be used as an end node or with stents or implant bodies 2 with very high restoring forces. However, the node 17 of Figure 3 is more complex to manufacture than the node 17 of Figure 2.

[0047] In the context of the invention, it is essential that the locking element prevents untying. When the invention refers to the locking element being in active engagement with the locking bay, this can mean that it penetrates the locking bay as shown in Figure 2 or prevents the locking bay from shifting, for example, by preventing the locking bay from sliding off the retaining bay (Figure 3). The term "active engagement" 1 stands as a representative for fixing the knot with at least two contacting bays of a flexible traction element, in particular a single traction element.

[0048] The embodiment shown in Figure 4 differs from that shown in Figure 1 in that the tip 6 has a concave recess 22 on its proximal side 7, into which the distal end 23 of the locking element 15 engages. In this embodiment, the tip 6 has a longitudinal channel through which a guide wire can be inserted. The difference from the embodiment shown in Figure 1 is that there is no separate handle for the flexible traction element 8, as the traction element 8 is attached to the channel 11 of the insertion system 3. There is only a single handle 16 for the locking element 15 at the proximal end of the insertion system 3. The operating principle is the same as in the embodiment shown in Figure 1. The locking element 15 can be retracted using the handle 16, and the knots 17 can be released to expand the implant body 2. The insertion system 3 is then retracted.The flexible traction element 8 is attached to the insertion system 3 and is retracted simultaneously with the insertion system 3.

[0049] Figures 5 and 6 show two further embodiments of node 17. The node 17 of Figure 5 is very similar to that of Figure 2; however, the orientation of the retaining bay 21 is reversed compared to the embodiment of Figure 2, i.e., the retaining bay 21 does not engage the locking bay 19 radially from the inside, but radially from the outside. While in the embodiment of Figure 2 three longitudinal segments of the locking element 15 are arranged radially outside and only one longitudinal segment of the flexible tension member 8 is arranged radially inside, the opposite is true in the embodiment of Figure 5. There, three longitudinal segments are found, viewed radially, between the locking element 15 and the outer surface of the implant body 2.

[0050] The node 17 of Figure 6 represents a combination of the nodes of Figures 3 and 5 and lies between the two aforementioned nodes in both complexity and durability. As in the embodiment of Figure 5, the retaining bay 21 is located below the locking element 15. The locking bay 19 is guided with one leg radially inward through the retaining bay 21, then with its arc radially outward over the locking element 15 and then again radially inward, and with its second leg led laterally outward from under the retaining bay 21. This is an open bay. A second curve follows the second leg, with the curve being guided radially outward over both legs of the retaining bay 19 in order to then engage the locking element 15 radially inward. At this node 17 as well, three longitudinal sections of the elastic tension member 8 lie radially inward, i.e.,below the locking body 15 and a length section above the locking body 15. The reverse arrangement is also possible.

[0051] Figures 7 and 8 show an implant 1 with a Y-shaped implant body 2, which has two distal ends and two distal tips 6a, 6b on two branches of the implant carrier 4. The special feature is that this implant 1 has three locking elements 15, 15a, 15b. The first locking element 15 holds the implant body 1 in its unexpanded state. A distal loop 9 is provided to also compress the two branches 24, 25, so that the entire implant has a substantially cylindrical shape.

[0052] Figure 8 shows the embodiment of Figure 7 after the actuating end 16 of the locking element 15 has been pulled far enough to release the loop 9. The two branches 24, 25 have straightened and are now at the desired angle to each other. Now, the actuating ends 16a and 16b of the locking elements 15a, 15b for the branches 24, 25 can be pulled back successively, so that the individual branches 24, 25 are expanded. Subsequently, the actuating end 16 of the locking element 15 can be pulled back completely, thereby also releasing a main body 26 of the implant body 2. The insertion system 3 can then be pulled back completely, along with the flexible traction elements 8 attached to the insertion system 3. This can be a single flexible traction element 8 that is looped around both the main body and the branches 24, 25. Separate flexible traction elements (8) may also be provided.

[0053] The embodiment shown in Figure 9 features an outer tube 27 over which the implant 1 is placed. In this variant, only the branches 24, 25 of the Y-shaped stent are provided with locking elements 15a and 15b. The flexible traction elements 8, which are looped around the branches 24, 25, can be actuated independently of one another via actuating ends 16a, 16b and thus released independently of one another after placement.

[0054] The system according to the invention is suitable for insertion systems 3 in which a guide wire 28 has first been inserted. The implant carrier 4 has a longitudinal channel through which the guide wire 28 is guided. The guide wire 28 can pass through the entire insertion system from the distal to the proximal end. So-called rapid-exchange systems provide that the guide wire 28 is guided over the tip 6 to a radial exit opening 29 located proximal to the implant body 2 and then led laterally out of the channel 11 of the insertion system 3b. This design has the advantage that significantly shorter guide wires can be used. The insertion system according to the invention is therefore easier to handle. Only the short portion of the implant 1 needs to be threaded onto the guide wire 28. Furthermore, the guide wire 28 does not obstruct the locking element 15, which is also guided through the channel 11.

[0055] Preferably, the locking element 15 is guided proximal to the radial exit opening 29 of the guide wire 28 into the channel 11, so that the wire-shaped locking element 15 and the guide wire 28 do not touch. Reference symbol:

[0056] 1 - Implant

[0057] 2 - Implant body

[0058] 3 - Insertion system

[0059] 3a - Introduction system

[0060] 3b - Introduction system

[0061] 4 - Implant carrier

[0062] 5 - End of 4

[0063] 6 - Peak at 5

[0064] 6a - Top

[0065] 6b - Top

[0066] 7 - proximal side of 6 8 - flexible traction element

[0067] 9 - Loop of 8

[0068] 10 - Loop of 8

[0069] 11 - Channel of 3

[0070] 12 - Handling of 3

[0071] 13 - proximal end of 8 14 - actuation end of 8 15 - locking element

[0072] 15a- Barrier body

[0073] 15b- Locking element

[0074] 16 - End of operation

[0075] 16a- End of operation

[0076] 16b- End of operation

[0077] 17 - nodes

[0078] 18 - End of 9

[0079] 19 - Locking bay at 18 20 - End of 9

[0080] 21 - Laying bay at 20

[0081] 22 - admission for 23

[0082] 23 - Distal end of 15 - Branch from Y-stent - Branch from Y-stent - Main body of Y-stent - Outer tube

[0083] - Guide wire

[0084] - Exit opening for 28

Claims

Patent claims 1. Implant (1 ) with the following features: a. an implant body (2) is expandable from a non-expanded state to an expanded state; b. the implant body (2) is self-expanding; c. it has a flexible traction element (8) which encircles the implant body (2) with at least one loop (9, 10) to hold the implant body (2) in the non-expanded state; d. the loop (9, 10) has a locking bay (19) at one end (18) which engages with a locking element (15, 15a, 15b); e. the locking element (15, 15a, 15b) is displaceable relative to the locking bay (19) in order to release the locking bay (19) and the loop (9,10) and to expand the implant body (2).

2. Implant (1) according to claim 1, characterized in that the flexible traction element (8) is a wire or a linear textile structure with at least one fiber.

3. Implant (1) according to claim 1 or 2, characterized in that the loop (9, 10) has at one end (18) the locking recess (19) and at its other end (20) a retaining recess (21), wherein the locking recess (19) is guided through the retaining recess (21).

4. Implant (1) according to one of claims 1 to 3, characterized in that the traction element (8) is guided in several loops (9, 10) around the implant body (2).

5. Implant (1) according to claim 4, characterized in that the locking body (15, 15a, 15b) is connected by locking bays (19) of several loops (9, 10) is guided or is engaged with locking bays (19) of several loops (9,10).

6. Implant (1) according to one of claims 1 to 5, characterized in that the locking element (15, 15a, 15b) is rod-shaped.

7. Implant (1) according to one of claims 1 to 6, characterized in that the locking element (15, 15a, 15b) has an actuating end (16, 16a, 16b) to remove the locking element (15, 15a, 15b) from the implant body (2) to release the loops (9, 10).

8. Implant (1) according to one of claims 1 to 7, characterized in that the implant body (2) is a stent.

9. Implant (1) according to claim 8, characterized in that the implant body (2) is a bifurcated stent with a main body (26) and at least one branch (24, 25) with independently actuable locking elements (15, 15a, 15b).

10. Insertion system for an implant (1) according to one of claims 1 to 9, characterized in that the implant (1) is arranged on an implant carrier (4) which has a tip (6, 6a, 6b) at its end (5) which projects towards the implant (1), wherein the tip (6, 6a, 6b) has a receptacle (22) for a distal end (23) of the locking body (15) on its proximal side (7) facing the implant (1).

11. Insertion system according to claim 10, characterized in that the receptacle (22) is concave.

12. Introduction system according to claim 10 or 11, characterized in that the implant (1 ) is a Y-stent, wherein in each branch (24, 25) a branch of a forked implant carrier (4) is arranged.

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