Patent Description:
Aneurysms can be intravascularly treated by delivering a treatment device to the aneurysm to fill the sac of the aneurysm with embolic material and/or block the neck of the aneurysm to inhibit blood flow into the aneurysm. When filling the aneurysm sac, the embolic material can promote blood clotting to create a thrombotic mass within the aneurysm. When treating the aneurysm neck without substantially filling the aneurysm sac, blood flow into the neck of the aneurysm can be inhibited to induce venous stasis in the aneurysm and facilitate natural formation of a thrombotic mass within the aneurysm.

In some current treatments, multiple embolic coils, and other embolic implants (e.g. braids) are used to either fill the aneurysm sac or treat the entrance of the aneurysm neck. An embolic implant is attached to a tubular delivery member and delivered via a delivery catheter to an aneurysm. During delivery, the embolic implant can be engaged to the delivery member's implant engagement/deployment system (referred to herein equivalently as an "engagement system" or "deployment system"). When the embolic implant is in position, the deployment system can release the implant, the implant can be left implanted, and the delivery member can be retracted. Some treatments utilize a mechanical engagement/deployment system that can be actuated by a physician to release the implant by pulling one or more wires or other elongated members referred to generically herein as a "pull wire".

Some of the challenges that have been associated with delivering and deploying embolic implants with delivery members having mechanical engagement systems include premature release of the implant during navigation of tortuous anatomy and/or movement of the delivery member. Premature release can be due to push back from densely packed treatment sites.

There is therefore a need for improved methods, devices, and systems to facilitate implantation of embolic coils and other implants facing similar challenges.

<CIT> relates to a micro-coil assembly including: a micro-coil unit which is inserted into a cerebral aneurysm region of a patient and prevents inflow of blood by leading the blood to clot; a coil pusher unit which is arranged adjacent to the micro-coil unit and carries the micro-coil unit to the cerebral aneurysm region of the patient.

<CIT> relates to packaging including a first packaging tube and a container, wherein the implant is movable from the container into the first tube and maintained within the first tube in a second condition, the implant having a first transverse dimension in the first condition and a second transverse dimension in the second condition, the second transverse dimension being less than the first transverse dimension.

<CIT> relates to a delivery member for delivering and deploying an intravascular medical device.

Methods are not explicitly recited in the claims but are considered as useful for understanding the invention.

The above and further aspects of this invention are 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 various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention. The figures depict one or more implementations of the inventive devices, by way of example only, not by way of limitation.

When used herein, the terms "tubular" and "tube" are to be construed broadly and are not limited to a structure that is a right cylinder or strictly circumferential in cross-section or of a uniform cross-section throughout its length. For example, the tubular structure or system is generally illustrated as a substantially right cylindrical structure. However, the tubular system may have a tapered or curved outer surface without departing from the scope of the present invention.

Systems, implants, and methods are disclosed herein which may be able to attain more precise and repeatable implant detachment. Placement of embolic coils and other implants facing challenges such as partially implanted implants becoming difficult to reposition, shifted delivery systems due to push back during implantation, and/or prematurely released implants may be facilitated. To meet some or all of these needs, example implants can include a detachment feature having a proximal sleeve through which a pull wire can be extended and/or a distal extension which can engage a distal end of the pull wire. The proximal sleeve can be sized, positioned, and otherwise configured to align the pull wire to the distal extension and/or the proximal sleeve can provide a friction force against the pull wire. Preferably, the proximal sleeve provides friction from a disk or tabs that are positioned to press into the pull wire. The disk or tabs can include a biocompatible material(s) that is preferably elastic. The distal extension can provide a hard stop to prevent the distal end of the pull wire from moving further into the implant. The distal extension preferably is shaped in a half-sphere or cone. The sleeve and the distal extension can be respectively formed by milling of the material of the detachment feature and/or attaching material to the detachment feature. Preferably the detachment features can be laser cut from a flat sheet material. The flat sheet material is preferably a radiopaque material that can be welded or otherwise affixed by any suitable means to the embolic coil, braided tube, or other embolic structure of the implant.

<FIG> is an illustration of a cut-away view an implant <NUM> attached to a delivery member <NUM>. The implant <NUM> includes an embolic coil <NUM>, a detachment feature <NUM>, and a stretch resistant fiber <NUM>. Proximal welds <NUM> join a proximal end <NUM> of the embolic coil <NUM> to the detachment feature <NUM>. A distal weld <NUM> joins a distal end <NUM> of the embolic coil <NUM> to the stretch resistant fiber <NUM>. Portions of the coil <NUM>, welds <NUM>, <NUM>, and delivery tube <NUM> are shown in a cut-away view for the purposes of illustration.

The detachment feature <NUM> can include a distal opening <NUM> through which the stretch resistant wire <NUM> is looped, a proximal opening <NUM> through which a loop wire <NUM> extends, a sleeve <NUM> through which a pull wire <NUM> extends, and a distal extension <NUM> positioned to engage a distal end of the pull wire <NUM>. The detachment feature <NUM> can include a bridge <NUM> positioned between the distal opening <NUM> and the proximal opening <NUM> upon which the sleeve <NUM> is mounted. The pull wire <NUM> can extend through a loop opening <NUM> of the loop wire <NUM> to secure the detachment feature <NUM> to the delivery member <NUM>. The loop wire <NUM> can extend through a lumen of a delivery tube <NUM> of the delivery member <NUM> and be under tension, thereby compressing a distal section of the delivery tube <NUM> having a spiral cut <NUM>.

Example delivery members and engagement/deployment systems are described in <CIT> and <CIT>.

<FIG> is an illustration of a side view of the detachment feature <NUM>, loop wire <NUM>, and pull wire <NUM>. The embolic coil <NUM> and the delivery tube <NUM> are omitted for the sake of the illustration. The detachment feature <NUM> can have a substantially flat profile, which provides flexibility in directions into and out of the page in relation to the orientation illustrated in <FIG>. The detachment feature <NUM> can have a planar back side <NUM> and a front side <NUM> opposite the planar back side <NUM>. The distal extension <NUM> and the sleeve <NUM> are positioned on the front side <NUM>.

The distal extension <NUM>, sleeve <NUM>, and/or bridge <NUM> can each facilitate in reducing instances of premature deployment. The detachment feature <NUM> can include any combination of these features.

The bridge <NUM> can be positioned distally from the proximal opening <NUM>. As the loop wire <NUM> presses into the pull wire <NUM> at the proximal opening <NUM> of the detachment feature <NUM>, the pull wire <NUM> may bend in response. The bridge <NUM> can provide an opposite force to support the pull wire <NUM> and provide a limit to which the pull wire <NUM> is able to bend.

The sleeve <NUM> can provide a friction force against the pull wire <NUM> to inhibit longitudinal movement of the pull wire <NUM>. The sleeve is preferably positioned on the bridge <NUM>; however, the sleeve can alternatively be positioned in a proximal direction <NUM> in relation to the proximal opening <NUM> or in a distal direction <NUM> in relation to the distal opening <NUM>. When the detachment feature <NUM> includes the distal extension <NUM> and the sleeve <NUM>, the sleeve can function to align the pull wire <NUM> to the distal extension <NUM>, in which case the sleeve <NUM> may or may not also provide a friction force against the pull wire <NUM> to inhibit longitudinal movement of the pull wire <NUM>.

The distal extension <NUM> is preferably at a distal end of the detachment feature <NUM> so that the pull wire <NUM> can have maximum extension through the loop opening <NUM> of the loop wire <NUM> without reducing flexibility of the embolic coil <NUM>.

To facilitate repositioning of the implant, the stretch resistant fiber <NUM> can extend through the embolic coil <NUM> and limit separation of windings of the coil <NUM> when the coil <NUM> is bent and/or pulled. By limiting the separation of the windings, the embolic coil <NUM> is less likely to become tangled when partially implanted and less likely to be stretched or otherwise deformed when retracted. The embolic coil <NUM> can thereby be more easily repositioned compared to an embolic coil lacking the stretch resistant fiber <NUM>.

To reduce effects of push back during implantation, the detachment feature <NUM> can be sized and affixed to the embolic coil <NUM> to provide an embolic coil implant <NUM> with a highly flexible proximal section. An embolic coil implant <NUM> having a highly flexible proximal section can reduce push back force on the delivery tube <NUM> and thereby mitigate the effects of the delivery tube <NUM> shifting. Additionally, or alternatively, the detachment feature <NUM> can be sized to mate with a delivery tube <NUM> having a highly flexible distal section, and the highly flexible distal section of the delivery tube can mitigate the effects of the delivery tube shifting. When an embolic coil implant <NUM> having a highly flexible proximal section is mated to a delivery tube <NUM> having a highly flexible distal portion, the combination of the flexible distal section of the delivery tube <NUM> and the flexible proximal section of the implant <NUM> can further mitigate the effects of delivery tube shifting. Although not illustrated, the detachment feature <NUM> can be tapered as it extends further within a lumen <NUM> of the embolic coil <NUM> to allow the embolic coil <NUM> to have additional flexibility where the embolic coil <NUM> surrounds the tapered region. The flat profile of the detachment feature <NUM> and the minimal number of fused windings near the proximal end <NUM> of the coil <NUM> can also allow for high flexibility near the proximal end <NUM> of the embolic coil <NUM>.

<FIG> are illustrations of the sleeve <NUM> of the detachment feature <NUM>. <FIG> is a perspective view of a first example sleeve 29a and the distal opening <NUM> of the detachment feature <NUM>. <FIG> is a planar view of a sleeve opening 46a of the first example sleeve 29a. The first example sleeve 29a includes tabs 48a extending inwardly from a perimeter of the sleeve opening 46a to converge on a pull wire opening 49a. <FIG> is a perspective view of a second example sleeve 29b and the distal opening <NUM> of the detachment feature <NUM>. The second example sleeve 29b includes a disk 48b within a sleeve opening 46b. The disk 48b has a pull wire opening 49b at its center.

The tabs 48a and disk 48b of the sleeve 29a, 29b can include a biocompatible material that is preferably elastic. The tabs 48a and disk 48b of the sleeve 29a, 29b can include one or more bioabsorbable materials. Example suitable materials can include silicone, alumina, bioglass, stainless steel, cobalt-chromium alloy, ceramic biomaterial (e.g., hydroxyapatite or zirconia), and polymers (e.g., polyvinylchloride (PVC), polyethylene (PE), polypropylene (PP), polytetrafluoroethylene (PTFE), polymethylmethacrylate (PMMA), trimethylcarbonate, TMC NAD-lactide, polycaprolactone (PCA), polylactic acid (PLA), polycaprolactone (PCL), polyglycolic acid (PGA), polydioxanone (PDO), polybutyrolactone (PBL), polyvalerolactone (PVL), and poly(lactide-co-glycolide) (PLGA)).

<FIG> are illustrations of the distal extension <NUM> of the detachment feature <NUM>. <FIG> illustrates a first example distal extension 35a having a shallow cavity 37a for receiving the distal end of the pull wire <NUM>. <FIG> illustrates a second example distal extension 35b having a deeper cavity 37b for receiving the distal end of the pull wire <NUM>. Preferably the distal extension <NUM> has a semi-conical shape such as illustrated in <FIG>.

<FIG> is an illustration of dimensions of the detachment feature <NUM>. The proximal portion <NUM> has a first length L1 measured from a proximal end of the detachment feature <NUM> to a shoulder 36a of the detachment feature <NUM>. The distal portion <NUM> has a second length L2 measured from the shoulder 36a to a distal end of the detachment feature <NUM>. The distal opening <NUM> of the detachment feature <NUM> has a third length L3. The detachment feature <NUM> can have a first shoulder 36a and a second shoulder 36b opposite the first shoulder 36a. The shoulders 36a, 36b can be configured to be welded or otherwise affixed to the proximal end <NUM> of the embolic coil <NUM>. The shoulders 36a, 36b can be offset by a fourth length L4. The fourth length L4 can be dependent upon a thickness of windings of the coil <NUM>. Preferably, the fourth length L4 measures about half of a diameter D1 a winding of the coil <NUM> (see <FIG>).

The proximal portion <NUM> has a first width W1 that is a maximum width of the proximal portion <NUM>, a second width W2 that is a minimum width of a main part of the proximal portion <NUM>, and a third width W3 of a proximal extension <NUM>. The proximal extension <NUM> is sized to fit within a lumen of the delivery tube <NUM>, therefore the third width W3 is less than, and preferably approximately equal to, a diameter of the lumen of the delivery tube <NUM>. The distal portion <NUM> of the detachment feature <NUM> has a fourth width W4 that is less than a diameter of the lumen <NUM> of the embolic coil <NUM>. In some examples, although not illustrated, the width of the distal portion can taper, becoming narrower in the distal direction <NUM> of the detachment feature <NUM> to improve flexibility of the embolic coil <NUM> near the proximal end <NUM> of the coil. The distal opening <NUM> of the detachment feature <NUM> can have a fifth width W5.

The proximal opening <NUM> can have an atraumatic surface <NUM> against which the loop wire <NUM> can press to minimize abrasion to the loop wire <NUM> by the detachment feature <NUM>. The distal opening <NUM> can have an atraumatic surface <NUM> against which the stretch resistant fiber <NUM> can press to minimize abrasion to the stretch resistant fiber <NUM> by the detachment feature <NUM>.

<FIG> is an illustration of a cut-away view of the implant <NUM> attached to the delivery member <NUM> with the pull wire <NUM> under compression. Because the distal extension <NUM> inhibits the pull wire <NUM> from moving distally into the embolic coil <NUM>, the pull wire <NUM> can be loaded under compression within the delivery tube <NUM>.

<FIG> is an illustration of a system <NUM> including the implant <NUM> and delivery member <NUM> navigating vasculature through a guide catheter <NUM>. As the system <NUM> navigates bends A, B, C the system <NUM> tends to extend to the extremes of the bends A, B, C. Similarly, as the delivery tube <NUM> bends, the pull wire <NUM> tends to move to extremes of the delivery tube <NUM> at the bends A, B, C. Without placing the pull wire <NUM> under compression as illustration in <FIG> and without providing a friction force from the sleeve <NUM> to the pull wire <NUM>, the distal end of the pull wire <NUM> can move in the proximal direction <NUM> in relation to the loop wire opening <NUM> as the system <NUM> navigates the bends A, B, C. In extreme circumstances, the distal end of the pull wire <NUM> can travel proximally past the loop wire opening <NUM> to cause premature release of the implant <NUM>.

As described here, however, by placing the pull wire <NUM> under compression as illustrated in <FIG>, the pull wire <NUM> has slack to accommodate movement to the extremes of the delivery tube <NUM> in the bends. If the detachment feature <NUM> includes a sleeve <NUM> that provides frictional force against the pull wire <NUM>, the sleeve can provide tension to the pull wire <NUM> to prevent the pull wire <NUM> from moving to the extremes of the delivery tube <NUM>. These mitigating measures can be used alone or in combination to reduce the likelihood of premature release of the implant <NUM>.

<FIG> are a sequence of illustrations depicting detachment of the implant <NUM> from the delivery member <NUM>. A portion of the delivery tube <NUM> and a portion of the embolic coil <NUM> are cut away for illustration purposes.

<FIG> illustrates the engagement system including the pull wire <NUM> and the loop wire <NUM> in a locked configuration on the detachment feature <NUM> of the implant <NUM>. The delivery tube <NUM> includes a compressible portion <NUM> that can be compressed. The detachment feature <NUM> is secured to the delivery tube <NUM> by the loop wire <NUM> and the pull wire <NUM> as described in greater detail in relation to <FIG>.

<FIG> illustrates the pull wire <NUM> being drawn proximally to begin the release sequence for the implant <NUM>. The pull wire <NUM> proximally exits the distal extension <NUM> and/or the sleeve <NUM> of the detachment feature <NUM>.

<FIG> illustrates the instant the pull wire <NUM> exits the opening <NUM> of the loop wire <NUM>, allowing the distal end <NUM> of the loop wire <NUM> to fall away and exit the detachment feature <NUM>. As shown, there is now nothing holding the implant <NUM> to the delivery tube <NUM>.

<FIG> illustrates the end of the release sequence. Here, the compressible portion <NUM> has expanded/returned to its original shape and "sprung" forward. An elastic force E is imparted by the distal end <NUM> of the delivery tube <NUM> to the implant <NUM> to "push" it away to ensure a clean separation and delivery of the implant <NUM>. As made visible in <FIG>, the delivery tube <NUM> can include a notch <NUM> sized and configured to receive the proximal portion <NUM> of the detachment feature <NUM> of the implant <NUM>, and likewise the proximal portion <NUM> of the detachment feature <NUM> can be sized to fit within the notch <NUM> of the delivery tube <NUM>.

<FIG> are illustrations of an alternative system 100a including an alternative implant 10a attached to the delivery member <NUM>. The implant 10a includes a tubular braid 12a in place of the embolic coil <NUM>. The detachment feature 18a lacks the distal opening <NUM> and is otherwise similarly configured to the detachment feature <NUM> described and illustrated elsewhere herein. The system 100a is configured to deliver the implant 10a as illustrated in both <FIG>. A portion of the delivery tube <NUM> and a portion of the braid 12a are cut away in <FIG> for the sake of illustration.

<FIG> is a flow diagram of a method <NUM> of delivering and releasing an example implant. The method <NUM> can be applied to any of the example implants <NUM>, 10a disclosed herein, variations thereof, and alternatives thereto as understood by a person skilled in the pertinent art.

At step <NUM>, a distal end of a pull wire can be pressed into a distal extension of a detachment feature of an implant, thereby inhibiting the distal end of the pull wire from moving distally. The pull wire, detachment feature, and distal extension can respectively be configured similarly to corresponding components <NUM>, <NUM>, <NUM> disclosed herein, variations thereof, and alternatives thereto as understood by a person skilled in the pertinent art.

At step <NUM>, an implant delivery system, including the implant, the pull wire, and an elongated delivery tube, can be delivered through vasculature. The implant delivery system can be configured similarly to the implant delivery systems <NUM>, 100a disclosed herein, variations thereof, and alternatives thereto as understood by a person skilled in the pertinent art. The elongated delivery tube can be configured similarly to the delivery tube <NUM> disclosed herein, variations thereof, and alternatives thereto as understood by a person skilled in the pertinent art. The vasculature through which the delivery system is delivered can be tortuous. As the delivery system is delivered through tortuous vasculature, longitudinal movement of the distal end of the pull wire can be inhibited by a sleeve providing friction force against the pull wire. The sleeve can be configured similarly to the example sleeve <NUM> disclosed herein, variations thereof, and alternatives thereto as understood by a person skilled in the pertinent art. The distal end of the pull wire can be aligned to the distal extension by the sleeve.

Claim 1:
A system comprising:
an elongated delivery tube (<NUM>) configured to traverse vasculature and extending along a longitudinal axis of the system;
an embolic implant (<NUM>) comprising a detachment feature (<NUM>), the detachment feature comprising a distal extension (<NUM>) and a proximal opening (<NUM>);
a loop wire (<NUM>) affixed to the delivery tube and extending through the proximal opening of the detachment feature; and
a pull wire (<NUM>) extending through the delivery tube, extending through an opening in the loop wire, and characterised in that the pull wire is inhibited from moving distally by the distal extension of the detachment feature, and wherein the distal extension (<NUM>) is configured to engage a distal end of the pull wire.