Implant retention, detachment and delivery systems

Abstract

A medical implant delivery system is described. The system can be used to deliver various implants, including stents and / or stent grafts. The delivery system delivers and retains the implant in the target location.

Description

[0001] This application is a divisional application of application number 201680063495.X, application date September 16, 2016, and invention name “Implant retention, detachment and delivery system”.

[0002] Related Applications

[0003] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 220,905, filed on September 18, 2015, entitled “Implant Retention, Detachment, and Delivery System,” and U.S. Provisional Application Serial No. 62 / 222,063, filed on September 22, 2015, entitled “Implant Retention, Detachment, and Delivery System,” both of which are incorporated herein by reference in their entirety. Background Art

[0004] Medical implants such as stents are sometimes used to open blood vessels to mitigate the effects of plaque buildup, to prevent embolic material within an aneurysm from escaping, as flow diverters to restrict blood flow to certain areas, or for other reasons. These implants can be delivered via an implant delivery system, in which an elongated pusher is used to advance the implant through a catheter or sheath to the treatment site.

[0005] Delivery of implants such as stents can be challenging because many delivery systems do not allow repositioning of the implant after initial deployment. Therefore, if the implant is initially deployed to an undesirable location, the physician has no way to adjust the deployment position of the implant. Therefore, there is a need for an implant delivery system that provides the ability to reposition the implant, as well as a reliable release structure to deploy the implant. Summary of the invention

[0006] An implant delivery system is described. The implant delivery system can be used for stents, stent grafts, embolic coils, plugs, occluders, or other implants.

[0007] In one embodiment, an implant delivery system includes an implant and a retention structure.

[0008] In another embodiment, an implant delivery system includes an implant and a retention structure. The retention structure is disposed at a distal end portion of an elongated pusher and is composed of a mesh or ring structure.

[0009] In another embodiment, an implant delivery system includes an implant and a retention structure. The implant is fixed to the retention structure.

[0010] In another embodiment, an implant delivery system includes an implant and a retention structure. The retention structure includes elements for gripping the implant.

[0011] In another embodiment, an implant delivery system includes an implant and a retention structure, wherein the retention structure is separate from the implant and remains with the delivery system after the implant is detached from the delivery system.

[0012]

[0011] In another embodiment, an implant delivery system includes an implant, a retention structure, and one or more tethers.

[0013] In another embodiment, the implant delivery system comprises an elongated pusher member, and the pusher member has a retaining structure that is arranged at the distal portion of the pusher member and engages with the implant. The pusher, retaining structure and implant are arranged in a conduit or sheath, and can advance to the outside of the distal end of the conduit. The retaining structure can be a conical screen, which is arranged around the proximal end of the implant. The retaining structure can also be a plurality of rings, which are arranged around the proximal end of the implant or are arranged through the rings on the implant. The implant can also be further connected to the pusher by one or more tethers, and the tether can be broken by the mechanism that is at least partially located in the pusher. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and other aspects, features and advantages of embodiments of the present invention will become clear and elucidated by the following description of embodiments of the present invention, with reference to the accompanying drawings, in which:

[0015] Figure 1 An exemplary embodiment of a woven scaffold for use with the delivery system of the present invention is shown.

[0016] Figure 2 An exemplary embodiment of a woven bi-layer stent for use with the delivery system of the present invention is shown.

[0017] Figure 3 A side view of an embodiment of a delivery system having a mesh or woven retention structure is shown.

[0018] Figure 4 and 5 Shows Figure 3 Side view of the delivery system in various deployment states.

[0019] Figure 6 A side view of another embodiment of a delivery system having a mesh or woven retention structure and a tether is shown.

[0020] Figure 7 Shown is a side view of a thruster for use with various embodiments of the present invention.

[0021] Figure 8A side view of another embodiment of a delivery system having multiple loops including retention structures is shown.

[0022] Fig. 9 Shows Figure 8 Side view of the annular retention structure and thruster. DETAILED DESCRIPTION

[0023] Specific embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein; on the contrary, these embodiments are provided to make this disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art. The terms used in the detailed description of the embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, similar numbers represent similar elements.

[0024] U.S. Patent No. 8,182,506, 8,192,480, 8,460,332 and U.S. Patent Publication No. US20060200192, US20090062812, US20090163780, US20100268204, US20110301686, US20150289879 are incorporated herein by reference in their entirety. These references disclose implant detachment systems that can be used in combination with implant delivery systems described herein. These references generally disclose thermal detachment systems, wherein tethers are connected to implants and selectively fractured by activating heating coils to cause implant deployment.

[0025] The present invention generally relates to an implant delivery system having an implant retention structure that can improve implant deployment and retrieval of an implant that is not fully deployed. The implant retention structure of the present invention is particularly useful for deploying and repositioning stents, such as Figure 1 and 2 and those described in more detail below.

[0026] Figure 1 A stent 1 is shown that is woven or braided together from one or more threads 2 to form a generally cylindrical shape having a plurality of loops 4 around the circumference of both ends of the stent 1. The ends of the threads 2 may be connected to each other by welding, adhesives, or similar bonding mechanisms. Once the ends are welded or bonded, the threads 2 have no "free" ends.

[0027] Each of the rings 4 may include one or more coil members 6. Preferably, the coil members 6 are arranged around the wires 2 of the rings 4 and are composed of a radiopaque material to indicate the proximal and distal ends of the stent 1. In addition, these coil members 6 can provide additional anchoring force in the delivery device, as described in more detail below.

[0028] In one example, the distal end of the stent 1 includes at least two rings 4, each ring 4 having two coil members 6, and the proximal end of the stent 1 includes at least two rings 4, each ring 4 having one coil member 16. However, it should be understood that the stent 1 can include any number of coil members 6 on any number of rings 4.

[0029] Preferably, these coil members 6 are located near the central region of the ring 4 so that when the stent 1 is in a collapsed state, the coil members 6 are located near the extreme proximal and distal ends of the stent 1 .

[0030] Preferably, each coil member 6 is composed of a tantalum wire 5 that will surround a portion of the ring 4. Each coil member 6 can be composed of an independent tantalum wire 5 or a single tantalum wire 5 can form a plurality of coil members 6 (eg, Figure 1 As shown in Figure 1 As shown, the wire 5 can be connected to the coil member 6 at each end of the stent 100 by being positioned inside and within the lumen of the stent 1. Alternatively, the wire 5 can be woven into the wire 2 of the stent 1.

[0031] One specific technique for minimizing exposure of the distal coil 6 during withdrawal is to weave the stent 1 so that portions of the wire 2 overlap (i.e., are located at a greater outer diameter) the side of the loop 4 having the coil 6. Some smaller secondary loops 7 are woven to overlap a first side of the loop 4 including the coil 6, while other secondary loops 7 are woven underneath a second side of the loop 4.

[0032] Figure 2 FIG. 2 shows a preferred embodiment of a double-sided bracket 20 according to the present invention. Generally, the double-sided bracket 20 includes a Figure 1 The outer anchor stent 1 of the previously described stent 1 shown in FIG. The double-sided stent 20 also includes an inner flow transfer layer 22 disposed within the cavities and channels of the interior of the anchor stent 1. The inner flow transfer layer 22 is preferably made of wires 24 to form a screen-like structure.

[0033] The proximal end of the double-layer stent 20 includes a plurality of attachment members 26 that connect the flow transfer layer 22 to the anchor stent 1. The attachment members 26 can be composed of tantalum wire (in this case 0.001" in diameter) and are attached to the partial wire 2 and the wire 24. In another embodiment, the proximal end of the flow transfer layer 22 can be crimped onto the wire 2 of the anchor stent 1. In another embodiment, the partial stent 1 and the flow transfer layer 22 can be woven to be interwoven for attachment purposes.

[0034] Additional details of each stent 1 and 20 may be found in U.S. Patent Publication No. 2013 / 0245745, which is incorporated herein by reference in its entirety.

[0035] Figure 3 One embodiment of an implant delivery system 100 is shown having an elongated pusher 110 and a retention structure 102 extending from a distal portion of the pusher 110. The pusher 110, retention structure 102, and stent 1 (or another implant device) are positioned within a catheter 112 such that at least a portion of the retention structure 102 overlaps a proximal portion of the stent 1. The catheter 112 prevents the retention structure 102 and stent 1 from expanding from a radially compressed configuration prior to deployment.

[0036] refer to Figure 4 and 5 As the pusher 110 advances toward the distal end of the catheter 112, the retaining structure 102 tapers distally, allowing the stent 1 to similarly open. If the position of the stent 1 within the patient is not ideal, the pusher 110 and the attached retaining structure 102 can be approximately retracted into the catheter 112, causing the stent 1 to similarly compress and retract into the catheter 112 for repositioning and redeployment. The retaining structure 102 allows the stent 1 to be withdrawn even after the stent 1 is completely outside the catheter 112. This is important because until the stent 1 is completely outside the catheter 112, the exact position of the stent 1 after shortening and the true length of the stent 1 are not known. The retaining structure 102 allows more opportunities for accurate placement of the stent 1, so the physician has more opportunities to reset the stent 1 to the desired position if the initial deployment of the stent 1 is not ideal.

[0037] In one embodiment, the retention structure 102 is in the shape of a screen tube formed by one or more braided or woven wires (e.g., nickel titanium alloy wires). Alternatively, the screen can be formed by laser cutting or etching a solid tube structure. The proximal end of the retention structure 102 is fixed or mounted to the distal portion of the pusher 110 by welding, adhesives, mechanical fixation, or any combination of these methods.

[0038] The retaining structure 102 may also include one or more engagement elements 106 fixed to its screen 104 to assist the retaining structure 102 in engaging the support 1. The engagement elements 106 may be in the form of polymeric or metal projections in one or more shapes: spherical, elliptical, oval, pyramidal, rectangular, conical, truncated cone, truncated pyramidal, square or similar shapes. These engagement elements 106 may be attached by adhesives, wires or fiber bands or welding so that they protrude radially inward from the retaining structure 102. The engagement elements 106 are sized and placed on the screen 104 so as to fit at least partially into the gaps in the support 1. For example, the engagement elements 106 may be aligned with the gaps formed between the end rings 4, the secondary rings 7 or the woven threads of the support 1. In this regard, when the retention structure 102 and stent 1 are radially compressed within the catheter 112 (or delivery sheath), the engagement elements 106 prevent the stent 1 from moving laterally or axially within the catheter 112, preventing the stent 1 from disengaging until the retention structure 102 is exposed and radially expanded.

[0039] Figure 3 The retention structure 102 shown in has a trumpet-shaped or conical distal portion, which can help to determine that the stent 1 is locked or engaged during delivery and deployment. Before being connected to the pusher 110, the screen 104 can be heat-set to form a radially expanded tubular shape so that once the proximal end of the screen 104 is connected to the pusher 110, the screen 104 expands into a cone. Alternatively, before being connected to the pusher 110, the screen 104 can be heat-set to form a trumpet / conical shape. In another alternative embodiment, the screen 104 can be heat-set to form a cone, with a conical shape that suddenly tapers inward at its distal end to serve as a hook or annular ridge against the stent 1. In another alternative embodiment, the screen 104 can form a wave shape that increases and decreases in diameter along its length.

[0040] exist Figure 2-5 In an embodiment of the delivery system 100 , the pusher 110 may be an elongated member that is flexible enough to be advanced through the patient's vascular system while maintaining sufficient pushability to push the retention structure 102 and the stent 1 out of the catheter 112 .

[0041] refer to Figure 2-5 In operation, the distal end of catheter 112 is advanced to a target treatment location (or near such location) within the patient's vasculature. This positioning is achieved by first advancing a lead so that the distal end of the lead is at or near the target treatment location. A delivery sheath may be advanced over the lead so that its distal end is at the target treatment location, or catheter 112 may be advanced over the lead without a delivery sheath. A variety of different techniques for positioning a catheter in a patient's vasculature are known in the art and may be used in embodiments of the present invention.

[0042] Once the distal end of catheter 112 is at the desired location, pusher 110 is advanced distally. Figure 4 As shown, the distal end portion of the stent 1 is pushed out of the catheter 112 and begins to expand radially. As the stent 1 continues to move distally, the retaining structure 102 also moves distally and leaves the catheter 112, although all are outside the catheter 112, at least a portion of the proximal end of the stent 1 is maintained in a radially compressed (or partially compressed) configuration.

[0043] If the distal portion of the stent 1 is not deployed to the desired target position in the blood vessel, the pusher 110 can be withdrawn from the proximal end by the physician. As the retaining structure 102 is withdrawn, it compresses radially, thereby compressing the proximal end of the stent 1 to allow it to re-enter the lumen of the catheter 112. The engagement element 106 helps the retaining structure 102 to grasp and push the stent 1, ensuring that the stent 1 does not slip out of the retaining structure 102. Once a portion of the stent 1 re-enters the catheter 112, the remaining portion of the stent 1 can also be withdrawn into the catheter 112.

[0044] Finally, the catheter 112 is repositioned and the pusher 110 is advanced distally to deploy the stent 1 as described above. Once the retention structure 102 has been sufficiently advanced out of the catheter 112, as described above, the catheter 112 is moved distally. Figure 5 As shown, it is radially expanded to a sufficient size to be detached from the stent 1. The pusher 110 and the retaining structure 102 are withdrawn from the proximal end into the catheter 112, and the catheter 112 is withdrawn from the patient.

[0045] Figure 6 Another embodiment of a delivery system 120 is shown, which is generally similar in structure and function to the delivery system 100 described above. However, the delivery system 120 further includes a tether 122, which is connected to the pusher 110 and can be selectively released from the stent 1 when fully deployed at the desired target location. The tether 122 can be a monofilament fixed to the pusher 110 and attached to the proximal ring of the stent 1 (e.g., by adhesive, mechanical connection or welding). Figure 6 in (and optionally in Figure 8 and 9 The tether feature described in the foregoing description may be used to connect to the retention structure 102 or to replace the retention structure 102.

[0046] Figure 7 Shows Figure 6 1, which illustrates the decoupling function. Figure 7As shown, the stent 1 can be connected to the thruster 110 by a tether 122, and can be selectively activated to break the tether 122 and then release the stent 1. More specifically, the resistive heating coil 130 is connected to wires 131 and 132 that are selectively powered from a proximal power source. When powered, the heating coil 130 is heated and the tether 122 is broken. The heat shield 134 and the reinforcement ring 136 are arranged on the outer portion of the thruster 110 to thermally isolate and reinforce the structure of the thruster 110.

[0047] exist Figure 7 In the embodiment of the present invention, the tether 122 extends through the proximally directed coil portion 130 and the coil 140 of the stent 1 and is further bonded by the adhesive 140. However, the tether 122 can also be attached to both ends of the pusher 110 to form a ring around one or more of the end rings 4 of the stent 1.

[0048] Figure 8 Another embodiment of a pusher 110 is shown having a retention structure 150 comprised of a plurality of rings 152. The rings 152 may be pressed against the outer surface of each of the end rings 4 to help maintain the proximal portion of the stent 1 in a compressed configuration similar to the retention structure 102 described. Alternatively, each of the rings 152 may be placed through each of the stent rings 4 or 7.

[0049] If the ring 152 is located outside the stent ring 4 (i.e., does not pass through the ring 4), the delivery method is the same as Figure 4 and 5 The delivery system 100 is similar to that shown. If the ring 152 is placed through the stent ring 4 (i.e., in a "chain-like" chain-link fashion), the delivery method is similar to Figure 6 The delivery system 120 shown is similar to Figure 7 Detachment shown.

[0050] Although the retention structure 150 is shown to have three rings 152, a different number of rings 152 may be used, such as 2, 4, 5, 6, 7, 8, 9, or 10. In one embodiment, the number of rings 152 is equal to the number of stent rings 4 at the end of the stent 1. In another embodiment, one or more of the rings 152 may pass through more than one stent ring 4.

[0051] If the rings 152 are located outside of the stent ring 4 (i.e., not passing through the ring 4), they can be composed of a shape memory alloy. If the rings 152 are placed so as to pass through the stent ring 4 (i.e., in a "chain-like" chain-locking manner), the rings 152 are preferably composed of a polymer that can be detached or broken by a mechanism in the pusher 110. For example, the pusher 110 can be Figure 7 As shown, and therefore configured to generate heat to break at least one chain or location along the loop 152.

[0052] like Fig. 9 As shown, each loop 152 can also have two free ends, both of which are fixed inwardly to the pusher 110 (i.e., initially in a linear configuration), or each loop 152 can initially form a complete loop wire, where a single position on the loop is fixed within the pusher 110. In an arrangement with two free ends (i.e., a linear chain), it is preferred that only one end or portion of each chain of loops 152 passes through the heating coil 130 while a portion at the opposite end of the chain is located outside the heating coil 130. The chain can also pass through an insulating sleeve close to the heating coil 130 to thermally isolate it from the heat generated by the heating coil 130. In this regard, once the loop 152 is severed, after the break, the remaining portion of the chain of loops 152 remains connected to the pusher 110 through the heating coil 130, and the stent ring 4 is released from the pusher 110.

[0053] Other embodiments of the pusher 110 use a multiple chamber structure, wherein the heating coil 130 and the first portion of the ring 152 are located in an inner chamber, and the second portion of the ring 152 is located in a separate outer chamber. The separate chamber can prevent the second portion of the ring 152 from any contact with the heating coil 130.

[0054] Other embodiments can use multiple ring structures, such as a delivery ring 152 that grasps all stent rings 4 and a separate, individual delivery ring 152 that grasps only one stent ring 4. Other variants can use a delivery ring 152 that is less than the total number of stent rings 4 provided. Therefore, for example, three stent rings 4 can be used with two delivery rings 152. In another embodiment, one delivery ring 152 engages two stent rings 4, and other delivery rings 152 engage only one stent ring. Other embodiments can use multiple ring structures 152 (e.g., two delivery rings 152 capture each stent ring 4) for each stent ring 4 to further enhance retention. Variants are also possible, wherein a combination of each of the multiple described embodiments is used (e.g., some stent rings 4 use multiple delivery rings 152, some stent rings 4 use only a single delivery ring 152, and some delivery rings 152 grasp multiple stent rings 4).

[0055] It should be understood that elements or aspects from the various embodiments presented herein can be combined in a wide variety of different configurations. For example, one embodiment can use the sieve retention structure 102, the delivery ring retention structure 150, and the tether 122 to further enhance the retention capabilities of the implant delivery system.

[0056] The presence of one or more tethers 122 does not necessarily prevent the stent 1 from expanding after withdrawal from the catheter 112, because the stents 1 generally have a strong shape memory when delivered and quickly adopt their expanded state. However, if the tension of the tether 122 is high enough, the tension of the tether 122 can prevent the proximal portion of the stent 1 from expanding and thus keep the stent 1 connected to the retention structure 102. Springs, coils or tubes can be used to keep the tether 122 in a tense state to further enhance the tension of the tether 122.

[0057] For embodiments using one or more tethers 122, delaying the detachment of the tethers 122 until after the stent 1 is fully expanded can allow the stent 1 to be repositioned while the tether(s) 122 are attached, since the tether(s) 122 connect the stent 1 to the delivery pusher 110 (some other variations may still affect the repositioning capability such as the size and type of the stent 1 and the stenosis of the vessel). Once the retention structure 102 is detached from the tethers 122, the stent 1 is completely detached from the pusher 110 and may not be repositionable after this point.

[0058] The described delivery system embodiments can be used to deliver one or more implants, such as stents, stent grafts, embolic coils, occluders, plugs, and similar devices. Although examples of stents are described in the embodiments of this specification, any of these other implants can be used similarly. For example, in order to deliver the embolic coil, the sieve-like retention structure 102 supports the proximal portion of the embolic coil for releasable delivery. The proximal part of the embolic coil can have a receiving structure to accommodate the engagement element 106 of the retention structure 102. Other implants can also include a ring structure 4 in the proximal region of those implants.

[0059] Any drawings shown and / or described are not meant to be limited to what is shown, but are illustrative in nature. Similarly, any measurements and / or descriptions of materials are meant to be representational, approximate, and exemplary, and not expressly limiting.

[0060] Although the present invention has been described according to specific embodiments and applications, those skilled in the art may produce other embodiments and modifications based on the teachings without departing from the spirit or scope of the claimed invention. Therefore, it should be understood that the drawings and descriptions herein are provided by way of example to facilitate understanding of the present invention and should not be interpreted as limiting its scope.

Claims

1. A delivery system for an implant, include: an elongated thruster having a distal end and a proximal end; a retention structure comprising a plurality of rings, each of the plurality of rings being connected to a distal end of the elongated pusher and extending distally away from the elongated pusher; an implant positioned proximate a distal end of the elongated pusher; wherein a plurality of rings engage the implant; wherein the implant is a stent having a plurality of stent openings; wherein each of the plurality of rings is placed through one of the plurality of stent openings; and Each of the plurality of rings is composed of a polymer that breaks when heat is applied.

2. The delivery system according to claim 1, in, Each of the plurality of rings has two free ends, both of which are internally fixed to the elongated pusher.

3. The delivery system according to claim 1, in, Each loop is a round wire loop wherein a single location of the round wire loop is located within the elongated pusher.

4. The delivery system according to claim 1, in, The elongated thruster further includes a heating coil.

5. The delivery system of claim 4, further comprising an insulating sleeve located adjacent the heating coil within the elongated pusher.

6. The delivery system according to claim 5, in, Each of the plurality of loops has two ends respectively attached within the elongated pusher, wherein each of the plurality of loops is placed through the heating coil and the insulating sleeve so that activation of the heating coil breaks each of the plurality of loops only at the location of the heating coil.

7. A delivery system for an implant, include: an elongated thruster having a distal end and a proximal end; a plurality of loops comprised of shape memory alloy wires, each of the plurality of loops being connected to a distal end of the elongated pusher and extending distally away from the elongated pusher; the plurality of loops having a radially compressed configuration and a radially expanded configuration; a stent positioned proximate a distal end of the elongated pusher; as well as a screen having a tubular compressed shape and a conical expanded shape that opens distally toward the implant; The plurality of rings radially compress the proximal end of the stent in the radially compressed configuration and release the stent in the radially expanded configuration.

8. A delivery system for an implant, include: an elongated thruster having a distal end and a proximal end; a retention structure comprising a plurality of rings, each of the plurality of rings being connected to a distal end of the elongated pusher and extending distally away from the elongated pusher; an implant positioned proximate a distal end of the elongated pusher; wherein a plurality of rings engage the implant; Wherein, the retention structure further comprises a screen having a tubular compressed shape and a conical expanded shape, wherein the conical expanded shape opens distally toward the implant.

9. The delivery system according to claim 8, in, The retention structure further includes a tether connected to the implant and configured to be broken via activation of the heating coil in the elongated pusher.

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