Proximal link wire to prevent premature implant detachment

Abstract

Disclosed herein are various systems and methods for deploying an implant at a target location in a body vessel. The delivery system can include a delivery tube and a pull tube, the pull tube being at least partially disposed within a first lumen of the delivery tube. A link wire having two proximal ends can be welded to the pull tube, the distal end of the link wire can include a link wire loop. The pull wire can extend through the first lumen with the distal end positioned to secure the implant to the delivery system. The pull wire includes a proximal bend disposed around the link wire loop, the proximal bend being disposed proximally relative to the distal end of the link wire loop by a slack length. The slack length is effective to prevent the implant from prematurely detaching from the delivery system.

Description

[Technical field]

[0001] The present invention relates to aneurysm treatment devices, and more particularly to an improved delivery system for embolic implants that prevents premature implant deployment. [Background technology]

[0002] Numerous intravascular implant devices are known in the art. Many are mechanically deployed via a system combining one or more catheters and wires for delivery. Examples of implants that can be delivered mechanically include embolic elements, stents, grafts, drug delivery implants, flow diverters, filters, stimulation leads, sensing leads, or other implantable structures delivered through a microcatheter. Some obstetric and gastrointestinal implants can also be implanted via a similar system combining one or more catheters and wires. Devices that can be released or deployed by mechanical means vary greatly in design, but can use similar delivery catheter and wire systems. Many such catheter-based delivery systems include a wire to hold the implant within the catheter until the time of device release. These systems are subsequently actuated by retracting or pulling the wire relative to the catheter. Such wires are referred to herein as "pull wires."

[0003] One problem with current catheter-based delivery systems is premature detachment of the implantable device. Premature detachment occurs when the implant detaches from the delivery system before reaching the treatment site. This can occur due to the tortuosity the delivery system undergoes as it passes through the patient's vasculature, which can cause increased friction between the "pull wire" and the delivery system, causing the pull wire to move proximally while the delivery system moves distally. Summary of the Invention [Problem to be solved by the invention]

[0004] Thus, there is a need for an improved implant delivery system that prevents premature detachment of the implant when the implant is delivered through tortuous vasculature.The present disclosure is directed to this and other considerations. [Means for solving the problem]

[0005] Disclosed herein are various systems and methods for deploying an implant at a target location in a body vessel. The delivery system can include a delivery tube and a pull tube, the pull tube being at least partially disposed within a first lumen of the delivery tube. A link wire having two proximal ends can be welded to the pull tube, the distal end of the link wire can include a link wire loop. The pull wire can extend through the first lumen with the distal end positioned to secure the implant to the delivery system. The pull wire includes a proximal bend positioned around the link wire loop, the proximal bend being positioned proximally relative to the distal end of the link wire loop by a slack length. The slack length is effective to prevent the implant from prematurely detaching from the delivery system.

[0006] In one aspect, a delivery system for deploying an implantable medical device at a target location in a body vessel is disclosed. The delivery system can include a delivery tube including a first lumen extending therethrough. The delivery system can include a pull tube including a second lumen extending therethrough. The pull tube can be at least partially disposed within the first lumen. The delivery system can include a link wire including two proximal ends welded to the pull tube. The link wire can be at least partially disposed within the second lumen and can include a distal end including a link wire loop. The delivery system can include a pull wire extending through the first lumen. The pull wire can include a distal end positioned to secure the implantable medical device to the delivery system. The pull wire can include a proximal bend positioned around the link wire loop, the proximal bend positioned proximally at a slack length relative to a distal end of the link wire loop. The slack length can be effective to prevent premature detachment of the implantable medical device from the delivery system when the implantable medical device is delivered to a target location in a body vasculature.

[0007] In some embodiments, the two proximal ends of the link wires can be welded to the proximal end of the pull tube, and the distal ends of the link wires can extend at least partially into the first lumen.

[0008] In some embodiments, the pull wire includes a free end disposed distally relative to the distal end of the link wire loop.

[0009] In some embodiments, the delivery system can include a loop wire that includes a loop opening in a distal portion of the loop wire disposed near the distal end of the delivery tube and two loop wire attachment welds that attach respective loop wire proximal ends to the distal end of the delivery tube.

[0010] In some embodiments, the distal end of the delivery tube can include a compressed distal portion. The loop wire can be effective to hold the compressed distal portion in a compressed state while the implantable medical device is delivered to a target location in a body vessel. The compressed distal portion can be a spiral cut portion of the delivery tube. The compressed distal portion can be configured to impart a resilient force to the implantable medical device when the implantable medical device is deployed to a target location in a body vessel.

[0011] In some embodiments, the implantable medical device can include a locking member, and a loop opening can be positioned through the locking member, and a distal end of a pull wire can be positioned through the loop opening, thereby securing the implantable medical device to the delivery system.

[0012] In some embodiments, the pull wires may be coated with polytetrafluoroethylene (PTFE). In some embodiments, the slack length may be a distance greater than about 3 millimeters.

[0013] In some embodiments, the link wires can have greater column strength than the pull wires.

[0014] In some embodiments, proximal translation of the pull tube is configured to proximally translate the pull wire a distance greater than the slack length, thereby deploying the implantable medical device at a target location in a body vessel.

[0015] In some embodiments, the implantable medical device may be an embolic coil.

[0016] In another aspect, a method is disclosed. The method can include providing a delivery tube including a first lumen extending therethrough. The method can include providing a pull wire including a proximal bend. The method can include attaching a link wire loop at a distal end of the link wire to the proximal bend of the pull wire and positioning the distal end of the link wire at a slack length from the proximal bend of the pull wire. The method can include providing a pull tube including a second lumen extending therethrough and welding a proximal end of each of the link wires to the pull tube. The method can include extending a distal end of the pull wire distally into the first lumen to retract the distal end of the link wire and the pull tube at least partially into the first lumen. The method can include positioning a distal end of the pull wire and securing the implantable medical device to the delivery tube. The method can include preventing premature detachment of the implantable medical device from the delivery tube by the slack length as the implantable medical device is delivered to a target location in a vessel of the body. The method can include translating the pull wire proximally a distance greater than the slack length, thereby deploying the implantable medical device at a target location in a body vessel.

[0017] In some embodiments, welding the proximal ends of each of the link wires to the pull tube further includes welding the proximal ends of each of the link wires to the proximal end of the pull tube such that the link wires are at least partially disposed within the second lumen.

[0018] In some embodiments, the method can include positioning a free end of the pull wire distally relative to a distal end of the link wire loop.

[0019] In some embodiments, the distal end of the delivery tube can include a compressed distal portion, the compressed distal portion can include a spiral cut portion of the delivery tube. In some embodiments, securing the implantable medical device to the delivery tube can further include providing a loop wire including a loop opening at a distal portion of the loop wire and a proximal end of the loop wire. The method can include welding a proximal end of the loop wire proximal to the compressed distal portion. The method can include positioning the loop opening through a locking member of the implantable medical device and extending a distal end of a pull wire through the loop opening to secure the implantable medical device to the delivery tube.

[0020] In some embodiments, the method can include applying a resilient force to the implantable medical device by the compressed distal portion when the implantable medical device is deployed at a target location in a body vessel.

[0021] In some embodiments, the pull wire is coated with polytetrafluoroethylene (PTFE). In some embodiments, the slack length can be a distance greater than about 3 millimeters. In some embodiments, the link wire can have greater column strength than the pull wire. In some embodiments, the implantable medical device can include an embolic coil. [Brief description of the drawings]

[0022] The above and further aspects of the present invention will be further discussed with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in the various drawings. The drawings are not necessarily to scale, with the focus instead being on illustrating the principles of the invention. The figures depict one or more implementations of the device of the present invention by way of example only, and not by way of limitation. [Figure 1] 1 is an illustration of a delivery system and implant according to an embodiment of the present invention. [Diagram 2]1 is an illustration of a delivery system passing through a body lumen, according to an embodiment of the present invention. [Figure 3A] 3 illustrates movement of the link wire as the delivery system is delivered through the body lumen of FIG. 2, according to an embodiment of the present invention. [Figure 3B] 3 illustrates movement of the link wire as the delivery system is delivered through the body lumen of FIG. 2, according to an embodiment of the present invention. [Figure 3C] 3 illustrates movement of the link wire as the delivery system is delivered through the body lumen of FIG. 2, according to an embodiment of the present invention. [Figure 4] 1 is an illustration of an embolic coil positioned within an aneurysm, according to an aspect of the present invention. [Figure 5A] 13A-13C illustrate the movement of a pull tube to deploy an implant at a treatment site, according to an embodiment of the present invention. [Figure 5B] 13A-13C illustrate the movement of a pull tube to deploy an implant at a treatment site, according to an embodiment of the present invention. [Figure 5C] 13A-13C illustrate the movement of a pull tube to deploy an implant at a treatment site, according to an embodiment of the present invention. [Figure 6] 1 illustrates an implant at the moment it is deployed from a delivery system, according to an embodiment of the present invention. [Figure 7] 1 is a flow chart of an exemplary method of using a delivery member, according to an aspect of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The following description of specific examples of the present invention should not be used to limit the scope of the present invention. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the present invention. The detailed description illustrates the principles of the present invention by way of example, not by way of limitation. Other examples, features, aspects, embodiments and advantages of the present invention will become apparent to those skilled in the art from the following description, which is by way of example, one of the best modes contemplated for carrying out the present invention. As will be appreciated, the present invention is capable of other different or equivalent aspects, all without departing from the present invention. The drawings and description should therefore be regarded as illustrative in nature, and not restrictive.

[0024] Any one or more of the teachings, expressions, variations, examples, etc. described herein may be combined with any one or more of the other teachings, expressions, variations, examples, etc. described herein. Thus, the teachings, expressions, variations, examples, etc. described below should not be considered in isolation from one another. In light of the teachings herein, various suitable methods that may be combined with the teachings herein will be readily apparent to those skilled in the art. Such modifications and variations are intended to be included within the scope of the claims.

[0025] As used herein, the term "about" or "approximately" with respect to any numerical value or range indicates a suitable dimensional tolerance that allows a portion or collection of components to function for the intended purpose described herein. More specifically, "about" or "approximately" may refer to a range of values ​​of ±10% of the recited value, e.g., "about 90%" may refer to a range of values ​​of 81% to 99%. Additionally, as used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject, and while use of the invention in human patients represents a preferred embodiment, it is not intended to limit the system or method to human use.

[0026] Referring to the figures, FIG. 1 illustrates an exemplary delivery system for deploying an implantable medical device 200 at a target location in a blood vessel of a body. The exemplary delivery system can include a proximal tube 110. The proximal tube 110 can include a first lumen 115 extending therethrough. A pull tube 130 can be disposed at least partially within the first lumen. The pull tube 130 can include a second lumen 135 extending therethrough. A link wire 120 can be disposed within the second lumen of the pull tube. The link wire 120 can include two proximal ends attached to a proximal end 132 of the pull tube 130. The link wire 120 can also include a link wire loop 126 located at a distal end of the link wire. The link wire loop 126 can form a loop around a proximal bend 156 of the pull wire 150. The pull wire 150 can extend distally from a proximal bend 156 of the pull wire 150 through the first lumen 115 to a distal end 154 of the pull wire 150. The distal end 154 can extend to the distal end 104 of the delivery system 100. The distal end 154 of the pull wire 150 can be secured through a loop wire opening 145 of the loop wire 140, which can secure the implant 200 to the delivery system 100. The pull wire can include a proximal free end 152 of the pull wire 150, which can be located distal to the proximal bend 156 of the pull wire 150. As shown in FIG. 1, the pull wire 150 can be in a “J” shaped hook configuration, with the proximal free end 152 located distal to the proximal bend 156 of the pull wire 150. The length measured between the link wire loop 126 and the proximal bend 156 of the pull wire 150 can constitute the slack length L. To deploy the implant 200 from the delivery system 100, the pull tube 130 can be translated proximally, which reduces the slack length L until the distal end of the link wire 124 abuts the proximal bend 156 of the pull wire 150. Further proximal movement of the pull tube 130 can be effective to deploy the implant 200 from the delivery system 100.Thus, the slack length L may be effective to prevent the implant 200 from prematurely detaching from the delivery system 100 as the delivery system 100 navigates the patient's tortuous vasculature when delivering the implant 200 to the treatment site. According to some embodiments, the slack length L may be a predetermined length effective to prevent premature detachment of the implant 200 from the delivery system 100. In some embodiments, the slack length L may be greater than about 3 millimeters.

[0027] The implant 200 may be positioned proximate the distal end 104 of the delivery system 100. The implant 200 may be of any type known in the art, and in a preferred embodiment, the implant 200 may be an embolic coil. The implant 200 may include a microcoil 210 effective to treat an aneurysm located at the distal end of the implant 200. At the proximal end of the implant 200, there may be a detachment feature 230. The detachment feature 230 may be provided as a proximal key having a locking member 218 through which the loop wire opening 145 of the loop wire 140 is positioned. After the loop wire opening 145 is positioned through the locking member 218 of the detachment feature 230, the distal end 154 of the pull wire 150 may be positioned through the loop wire opening 145 to secure the implant 200 to the delivery system 100. The loop wire 140 may further include a loop wire proximal end 141 attached to a distal portion of the proximal tube 110 by a respective loop wire attachment weld 142. The loop wire attachment weld 142 may be located just proximal to the compressed distal portion 118 of the proximal tube 110. According to some embodiments, the compressed distal portion 118 may be formed from a helical cut portion of the proximal tube 110 formed by a laser cutting operation. Additionally or alternatively, the compressible portion may be formed of a winding, a helical ribbon, or other configuration that allows for axial adjustment in accordance with the present invention. Preferably, the compressible distal portion 118 is in an elongated state at rest and will automatically or elastically return from the compressed state to the elongated state unless otherwise restrained. In some embodiments, the loop wire 140 is effective to hold the compressed distal portion 118 in a compressed state while the implant 200 is delivered to the treatment site.

[0028] The pull wire 150 can be constructed from any suitable material, for example, the pull wire 140 can be constructed from a shape memory material such as stainless steel or Nitinol. According to some embodiments, the pull wire 150 can be further coated with polytetrafluoroethylene (PTFE). In some embodiments, the link wire 120 can have a column strength greater than that of the pull wire 150. A link wire 120 having a column strength greater than that of the pull wire ensures that the link 120 is not broken while the medical professional translates the pull tube 130 proximally to deploy the implant 200. Additionally, the double weld 122 of the link wire 120 to the proximal end 132 of the pull tube 130 increases the fixation strength of the proximal end of the delivery system 100 compared to a delivery system including only a single pull wire attached to the proximal end of the delivery system.

[0029] 2 illustrates the positioning of a delivery system 100, including an implant 200, such as an embolic coil suitable for treating aneurysms, a guide catheter 300, and a proximal tube 110 and a pull wire 150, within a tortuous vasculature (vasculature not shown). At bends A, B, and C, the proximal tube 110 may extend to the sidewall of the guide catheter 300 on the respective outer curve of the respective bend, and similarly, the pull wire 150 may extend to the sidewall of the proximal tube 110 on the respective outer curve of the respective bend. During the procedure, the proximal tube 110 and the pull wire 150 may be fed in a distal direction D into the guide catheter 300, passing first through bend A, then bend B, then bend C. As the proximal tube 110 and the pull wire 150 navigate the bends, the pull tube 130 may translate proximally relative to the proximal tube 110. The slack length L ensures that proximal translation of the pull tube 130 relative to the proximal tube 110 does not prematurely deploy the implant 200 before the implant 200 is delivered to the treatment site. As the pull tube 130 moves proximally relative to the proximal tube 110, the pull wire 150 remains stationary relative to the proximal tube 110 as long as the pull tube 130 is translated a distance less than the slack length L. Thus, the slack length L can be effective to prevent premature detachment of the implant 200 from the delivery system 100.

[0030] 3A-3C show the movement of the link wire 120 as the delivery system is delivered through the body lumen of FIG. 2, according to an embodiment of the present invention. FIG. 3A shows the delivery system 100 after it has looped around bend A of FIG. 2. As shown in FIG. 3A, a length L remains between the distal end 124 of the loop wire 120 and the proximal bend of the pull wire 150, preventing the pull wire 150 from translating proximally due to proximal movement of the pull tube 130. FIG. 3B shows the delivery system 100 as it loops around bend B of FIG. 2. As shown in FIG. 3B, the delivery tube 130 and the link wire 120 move proximally relative to the proximal tube 110 a distance L1 by passing through the tortuous vasculature of FIG. 2 as the delivery system 100 advances toward the treatment site. Because distance L1 is less than the slack length L, the pull wire 150 remains stationary relative to the proximal tube 110, preventing the implant 200 from becoming prematurely detached. FIG. 3C illustrates the delivery system 100 as it navigates bend C of FIG. 2. As shown in FIG. 3C, as the delivery system 100 advances toward the treatment site, the delivery tube 130 and link wire 120 move proximally a distance L2 relative to the proximal tube 110 by passing through the tortuous vasculature of FIG. 2. Because distance L2 is less than the slack length L, the pull wire 150 remains stationary relative to the proximal tube 110, preventing the implant 200 from becoming prematurely detached.

[0031] 4 is an illustration of an embolic implant 12 being delivered through a catheter 250 and positioned within an aneurysm A of a blood vessel BV. The implants may loop and bend within the aneurysm sac to form a thrombotic mass. The implants may loop back on themselves and / or loop next to other implants. As the aneurysm A gradually fills, overlapping portions of the implants 12 may be pushed into one another.

[0032] 5A-5C illustrate the movement of the pull tube to deploy an implant at a treatment site, according to an embodiment of the present invention. FIG. 5A illustrates the configuration of the delivery system 100 after the delivery system has the rounded bend C of FIG. 2 and is approaching the treatment site as shown in FIG. 4. When the delivery system 100 is positioned such that the implant 200 is approaching the treatment site, the delivery system 100 still has slack L3 between the distal end 124 of the link wire 120 and the proximal bend 156 of the pull wire. To deploy the implant 200, the pull tube 130 can be translated proximally a distance greater than the slack L3 left between the distal end 124 of the link wire 120 and the proximal bend 156 of the pull wire. The arrow in FIG. 5A indicates that a medical professional utilizing the delivery system 100 can pull the pull tube 130 proximally to begin the deployment procedure of the implant 200 from the delivery system 100. In FIG. 5B, the pull tube 130 has been translated proximally a distance L3, thereby removing any slack left in the delivery system 100 between the distal end 124 of the link wire 120 and the proximal bend 156 of the pull wire 150. Further proximal translation of the pull tube relative to the proximal tube 110 is thus effective to deploy the implant 200 from the delivery system 100. FIG. 5C shows the delivery system 100 just before the implant 200 is released from the delivery system 100. In FIG. 5C, the pull tube 130 is translated an additional distance L4. Because there is no slack between the distal end of the loop wire 124 and the proximal bend 156 of the pull wire 150, any further proximal translation of the pull tube 130 is effective to translate the pull wire 150 proximally relative to the proximal tube 110. That is, when the medical professional operating delivery system 100 translates pull tube 130 a distance L4, pull wire 150 translates with pull tube 130 and link wire 120. As pull wire 150 is translated proximally, distal end 154 of pull wire 150 exits loop opening 145 of loop 140, thereby allowing the loop wire to exit detachment feature 230 of implant 200, releasing implant 200 at the treatment site. The arrows in Figures 5A and 5B indicate the direction of proximal translation of the link wire.The arrows in FIG. 5C indicate that both the link wire 120 and the pull wire 150 are translated together to release the implant 200 from the delivery system 100.

[0033] 6 illustrates an implant at the moment it is deployed from a delivery system, according to an embodiment of the present invention. As shown in FIG. 6, the implant 200 can be released from the delivery system 100 after the link wire 120 has translated proximally such that the pull wire 150 begins to translate proximally with the link wire as a single unit. The compressible distal portion 118 now expands / returns to its original shape and "springs" forward. An elastic force E is applied by the distal end 114 of the proximal tube 100 to "push" the medical device 200, ensuring complete detachment and delivery of the medical device 200.

[0034] The compressible distal portion 118 may have a difference in length (compressed distance) of about 0.5 mm to about 0.75 mm when measured in the compressed configuration and in the original uncompressed configuration. By using a larger compressed distance, a larger elastic force E can be achieved. The compressed distance can be determined by the dimensions of the loop wire 400, the shape of the locking member 218, and the shape of the distal end 114 of the proximal tube 110.

[0035] 7 is a flow chart of an exemplary method of using a delivery system, according to an embodiment of the present invention. At block 704, the method may include providing a delivery tube 110. The delivery tube may include a first lumen 115 extending therethrough. At block 708, the method may include providing a pull wire 150 including a proximal bend 156. At block 712, the method may include attaching a link wire loop 126 located at a distal end 124 of the link wire 120 to the proximal bend 156 of the pull wire 150. At block 716, the method may include providing a pull tube 130. The pull tube includes a second lumen 135 extending therethrough. At block 720, the method may include welding a proximal end 122 of each of the link wires 120 to the pull tube 130 to attach the link wires to the pull tube 130. At block 724, the method may include extending distal end 154 of pullwire 150 distally into the first lumen, thereby retracting distal end 124 of linkwire 120 at least partially into first lumen 115. At block 728, the method may include positioning distal end 124 of linkwire 120 a slack length L from proximal bend 156 of pullwire 150.

[0036] At block 732, the method may include positioning the distal end 154 of the pull wire to secure the implantable medical device 200 to the delivery tube 110. At block 736, the method may include preventing premature detachment of the implantable medical device 200 from the delivery tube 110 with the slack length L as the implantable medical device is delivered to the target location in the body vessel. At block 740, the method may include translating the pull tube proximally a distance greater than the slack length L, thereby deploying the implantable medical device 200 at the target location in the body vessel.

[0037] According to some embodiments, welding the proximal ends 122 of each of the link wires 120 to the pull tube 130 further includes welding the proximal ends 122 of each of the link wires 120 to the proximal end 132 of the pull tube 130 such that the link wires 120 are at least partially disposed within the second lumen 135.

[0038] According to some embodiments, the method can include positioning a free end 152 of a pull wire 150 distally relative to a distal end 124 of the link wire loop 126 .

[0039] According to some embodiments, the distal end 114 of the delivery tube 110 includes a compressed distal portion 118. The compressed distal portion 118 may include a spiral cut portion of the delivery tube 110. Securing the implantable medical device 200 to the delivery tube 110 may further include providing a loop wire including a loop opening in a distal portion 144 of the loop wire and a proximal end 141 of the loop wire, welding 142 the proximal end 141 of the loop wire proximal to the compressed distal portion 118, positioning the loop opening 145 through a locking member 218 of the implantable medical device 200, and extending a distal end 154 of the pull wire 150 through the loop opening 145 to secure the implantable medical device 200 to the delivery tube 110.

[0040] According to some embodiments, the method can include applying an elastic force E to the implantable medical device 200 by the compressed distal portion 118 when the implantable medical device 200 is deployed at a target location in a body vessel.

[0041] According to some embodiments, the pull wire 140 may be coated with polytetrafluoroethylene. In some embodiments, the slack length L may be a distance greater than about 3 millimeters. In some embodiments, the link wire 120 has greater column strength than the pull wire 140. In some embodiments, the implantable medical device may be an embolic coil.

[0042] The descriptions contained herein are examples of embodiments of the invention and are not intended to limit the scope of the invention in any way. As described herein, the invention contemplates many variations and modifications of the implantation system and related methods, including alternative geometries of system components, alternative materials, additional or alternative method steps, etc. Modifications that are obvious to one of ordinary skill in the art are intended to be within the scope of the following claims.

[0043] [Embodiment] (1) A delivery system for deploying an implantable medical device at a target location in a body vasculature, comprising: a delivery tube having a first lumen extending therethrough; a pull tube having a second lumen extending therethrough, the pull tube being at least partially disposed within the first lumen; a link wire having two proximal ends welded to the pull tube, the link wire being at least partially disposed within the second lumen, a distal end comprising a link wire loop; a pullwire extending through the first lumen, the pullwire having a distal end positioned to secure the implantable medical device to the delivery system and a proximal bend positioned around the linkwire loop, the proximal bend being positioned proximally relative to the distal end of the linkwire loop by a slack length; A delivery system, wherein the slack length is effective to prevent the implantable medical device from prematurely detaching from the delivery system when the implantable medical device is delivered to the target location in a vasculature of the body. (2) the two proximal ends of the link wires are welded to a proximal end of the pull tube; 2. The delivery system of claim 1, wherein the distal end of the link wire extends at least partially within the first lumen. (3) A delivery system as described in embodiment 1, wherein the pull wire has a free end disposed distally relative to the distal end of the link wire loop. (4) further comprising a loop wire; The loop wire is a loop opening in a distal portion of the loop wire disposed near a distal end of the delivery tube; 2. The delivery system of embodiment 1, comprising: two loop wire attachment welds that attach the proximal ends of each loop wire to the distal end of the delivery tube. (5) the distal end of the delivery tube comprises a compressed distal portion, and the loop wire is effective to hold the compressed distal portion in a compressed state while the implantable medical device is delivered to the target location in a blood vessel of the body; the compressed distal portion comprises a spiral cut portion of the delivery tube; The delivery system of embodiment 4, wherein the compressed distal portion is configured to impart an elastic force to the implantable medical device when the implantable medical device is deployed at the target location in the body's blood vessel.

[0044] (6) The delivery system of embodiment 4, wherein the implantable medical device comprises a locking member, the loop opening is disposed through the locking member, and the distal end of the pull wire is disposed through the loop opening, thereby securing the implantable medical device to the delivery system. (7) The delivery system of claim 1, wherein the pull wire is coated with polytetrafluoroethylene (PTFE). (8) A delivery system as described in embodiment 1, wherein the slack length is a distance greater than about 3 millimeters. (9) The delivery system of claim 1, wherein the link wire has a greater column strength than the pull wire. (10) The delivery system of embodiment 1, wherein proximal translation of the pull tube is configured to translate the pull wire proximally a distance greater than the slack length, thereby deploying the implantable medical device at the target location in the body vessel.

[0045] (11) The delivery system of embodiment 1, wherein the implantable medical device comprises an embolic coil. (12) A method comprising the steps of: providing a delivery tube having a first lumen extending therethrough; Providing a pull wire with a proximal bend; attaching a link wire loop at a distal end of a link wire to the proximal bend of the pull wire; providing a pull tube having a second lumen extending therethrough; welding a proximal end of each of the link wires to the pull tube; extending a distal end of the pull wire distally into the first lumen, thereby retracting the distal end of the link wire and the pull tube at least partially into the first lumen; positioning the distal end of the link wire a slack length from the proximal bend of the pull wire; positioning a distal end of the pull wire to secure an implantable medical device to the delivery tube; the slack length prevents premature detachment of the implantable medical device from the delivery tube as the implantable medical device is delivered to a target location in a body vessel; and and proximally translating the pull tube a distance greater than the slack length, thereby deploying the implantable medical device at the target location in the body vessel. (13) The method of embodiment 12, wherein welding a proximal end of each of the link wires to the pull tube further comprises welding a proximal end of each of the link wires to a proximal end of the pull tube such that the link wires are at least partially disposed within the second lumen. 14. The method of claim 12, further comprising positioning a free end of the pull wire distally relative to the distal end of the link wire loop. (15) a distal end of the delivery tube comprising a compressed distal portion; the compressed distal portion comprises a spiral cut portion of the delivery tube; Securing the implantable medical device to the delivery tube comprises: providing a loop wire, the loop wire comprising a loop opening at a distal portion of the loop wire and a proximal end of the loop wire; welding the proximal end of the loop wire proximal to the compressed distal portion; positioning the loop opening through a locking member of the implantable medical device; 13. The method of claim 12, further comprising extending the distal end of the pull wire through the loop opening to secure the implantable medical device to the delivery tube.

[0046] (16) The method of embodiment 15, further comprising applying a resilient force to the implantable medical device by the compressed distal portion when the implantable medical device is deployed at the target location in the body vessel. 17. The method of claim 12, further comprising coating the pull wire with polytetrafluoroethylene (PTFE). (18) The method of embodiment 12, wherein the slack length is a distance greater than about 3 millimeters. 19. The method of claim 12, wherein the link wires have a greater column strength than the pull wires. (20) The method of embodiment 12, wherein the implantable medical device comprises an embolic coil.

Claims

1. 1. A delivery system for deploying an implantable medical device at a target location in a body vessel, comprising: a delivery tube having a first lumen extending therethrough; a pull tube having a second lumen extending therethrough, the pull tube being at least partially disposed within the first lumen; a link wire having two proximal ends welded to the pull tube, the link wire being at least partially disposed within the second lumen, a distal end comprising a link wire loop; a pullwire extending through the first lumen, the pullwire having a distal end positioned to secure the implantable medical device to the delivery system and a proximal bend positioned around the linkwire loop, the proximal bend being positioned proximally relative to the distal end of the linkwire loop by a slack length; A delivery system, wherein the slack length is effective to prevent the implantable medical device from prematurely detaching from the delivery system when the implantable medical device is delivered to the target location in a vasculature of the body.

2. the two proximal ends of the link wires are welded to a proximal end of the pull tube; The delivery system of claim 1 , wherein the distal end of the link wire extends at least partially within the first lumen.

3. The delivery system of claim 1 , wherein the pull wire includes a free end disposed distally relative to the distal end of the link wire loop.

4. Further comprising a loop wire; The loop wire is a loop opening in a distal portion of the loop wire disposed near a distal end of the delivery tube; and two loop wire attachment welds attaching respective loop wire proximal ends to a distal end of the delivery tube.

5. the distal end of the delivery tube comprises a compressed distal portion, the loop wire being effective to hold the compressed distal portion in a compressed state while the implantable medical device is delivered to the target location in a blood vessel of the body; the compressed distal portion comprises a spiral cut portion of the delivery tube; 5. The delivery system of claim 4, wherein the compressed distal portion is configured to impart a resilient force to the implantable medical device when the implantable medical device is deployed to the target location in the body vessel.

6. 5. The delivery system of claim 4, wherein the implantable medical device comprises a locking member, the loop opening being disposed through the locking member, and the distal end of the pull wire being disposed through the loop opening, thereby securing the implantable medical device to the delivery system.

7. The delivery system of claim 1 , wherein the pull wire is coated with polytetrafluoroethylene (PTFE).

8. The delivery system of claim 1 , wherein the slack length is a distance greater than about 3 millimeters.

9. The delivery system of claim 1 , wherein the link wire has a greater column strength than the pull wire.

10. 2. The delivery system of claim 1, wherein proximal translation of the pull tube is configured to translate the pull wire proximally a distance greater than the slack length, thereby deploying the implantable medical device at the target location in the body vessel.

11. The delivery system of claim 1 , wherein the implantable medical device comprises an embolic coil.

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