Patent Description:
Temporary IVC filters are placed much like permanent filters, but are designed so that they may be retrieved in a separate endovascular procedure, generally from a femoral vein or internal jugular vein approach. Most of the currently available temporary filters include a hook-like feature with which they can be captured and received within a catheter or sheath for removal by employing a gooseneck snare or a multi-loop snare.

While retrieval is a simple procedure in principle, difficulty is often encountered capturing a filter's hook with the snare loop(s). Such difficulty is compounded when the filter is tilted or off-kilter in placement. Several filters are designed to avoid such orientation. However, the problem remains common because the device is not anchored into the IVC in a stable fashion. Constant blood flow in addition to blood clots can disorient the filter within the IVC making recapture difficult. Accordingly, there exists a need for a filter retrieval system with improved ease of use and/or less susceptibility to problems of filter orientation. <CIT> discloses devices including braid for delivery and/or retrieval of filters or other medical devices. <CIT> discloses a method and apparatus for facilitating transapical removal of a prosthetic heart valve. <CIT> discloses a tissue and organ extractor. <CIT> discloses a medical device for manipulation of a medical implant. <CIT> discloses a device for extraction of tissue and organs during laparoscopic procedures.

The invention is defined in the appended independent claim with optional features set out in the dependent claims. Embodiments hereof meet this need and others as applied to other medical device applications. For IVC filters, the subject systems may be used with a wide variety of filter architectures -- existing or otherwise. Accordingly, new filters may be designed for use with the subject retrievers in which fewer design constraints and/or compromises may be required of the filter design. Features of the subject system may be used in connection with existing and/or modified versions of the filters described in any of <CIT>; <CIT>; <CIT>; <CIT> and <CIT>, with commercially available devices including the OPTEASE, GUNTHER TULIP, CELECT and OPTION or others.

Embodiments hereof share a "funnel-trap" type architecture. This is advantageously constructed of heatset braid, possibly superelastic (SE) nickel-titanium alloy (Nitinol) braid. The funnel-trap end of a retrieval device includes a distal rim defining a distal opening, and a more proximal aperture or opening. A pocket is formed between the proximal opening and sides of the braid (or other material from which the device is constructed).

When an enlarged proximal end of an IVC filter or other implant is guided past the distal rim of the funnel shape it passes through the proximal opening for capture. Such an enlargement by be in the form of a nub bin or bump or a hook-type interface. In one example a locking sheath is advanced over and closes the trap to secure the enlarged end of the medical device in a pocket adjacent to the proximal opening or aperture. In another embodiment, the proximal aperture is cinched closed to effect capture. In yet another embodiment, crossing members act like a web to catch or entangle any hook or other feature passing into or through the proximal opening aperture.

The subject delivery and/or retrieval devices, kits in which they are included (with and without assembly), methods of use and manufacture (including assembly of the constituent components in viva or ex viva) are included for information only in the present disclosure. Some aspects of the same are described above, and more detailed discussion is presented in connection with the figures below.

Other systems, devices, methods, features and advantages of the subject matter described herein will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description.

The details of the subject matter set forth herein, both as to its structure and operation, may be apparent by study of the accompanying figures, in which like reference numerals refer to like parts. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the subject matter. Moreover, all illustrations are intended to convey concepts, where relative sizes, shapes and other detailed attributes may be illustrated schematically rather than literally or precisely.

Various exemplary embodiments are described below. Reference is made to these examples in a non-limiting sense, as it should be noted that they are provided to illustrate more broadly applicable aspects of the apparatuses and systems. Various changes may be made to these embodiments and equivalents may be substituted without departing from the scope of the invention as defined in the appended claims.

Before the present subject matter is described in detail, it is to be understood that this disclosure is not limited to the particular example embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

<FIG> shows a GUNTHER TULIP (Cook Medical, Inc. ) temporary IVC filter <NUM> with a hook <NUM> end interface for retrieval. As shown in <FIG> for a IVC filter <NUM>, the hook may be modified or substituted for a nubbin-type interface <NUM>. The nubbin (itself) may comprise a laser-formed or solder-formed protuberance or bump <NUM> on an extension <NUM> from a hub <NUM>. Alternatively, as shown in <FIG>, a/the filter retrieval interface <NUM> may comprise a band <NUM>' (e.g., a Pt marker band) mounted (e.g., by swaging, welding, gluing, etc.) on a/the extension <NUM>. However the enlargement is created, the funnel-trap structures described below are adapted to secure that feature for IVC filter retrieval.

<FIG> provides an overview of the subject system <NUM>. A funnel-trap structure <NUM> is shown made of heatset braid material <NUM>. The construction provides a flexible distal extension to an elongate shaft <NUM>. The shaft is received within an elongate sleeve <NUM> (that may be a commercially available catheter or sheath or a custom part of the overall system <NUM>) and may include a distal radiopaque marker band <NUM>.

The braid may comprise Nitinol (preferably that is superelastic (SE) at human body temperature), CoCr, Stainless Steel or another biocompatible material. It is advantageously braided material incorporating between <NUM> and <NUM>, or between about <NUM> and <NUM> filament "ends" in a <NUM>-over-<NUM>, <NUM>-over-<NUM>, <NUM>-over-<NUM> or other pattern. With (superelastic) Nitinol, the wire is advantageously between about <NUM> and about <NUM> inches in diameter. In which case, a supple and relatively "smooth" matrix surface is provided from which to construct the flexible funnel-trap architecture shown and described. The value of such a surface is in its atraumatic aspect and/or ability to help guide an IVC filter interface into position for capture even if it is oriented off-angle. Still, other wire sizes and/or end counts in a braid or other construction options are possible as well.

To assist with target device capture or recapture, the funnel trap structure <NUM> may be selectably directable. As indicated by the arrows in <FIG>, the material from which it is made can be heatset or otherwise configured to provide a bias in an angular direction. The angle of deployment may be selectable or fully straightened by relative position of a core member or obturator (not shown) or by a sleeve or catheter sheath as further described. Further positioning may be achieved by rotating the device as further illustrated. Alternatively, a curved, "L" or "J" shaped wire may be received within a lumen of shaft <NUM> that can be passed up to and/or through to the inside of the funnel trap structure. Made of superelastic Nitinol (or other) wire, this member can be used to selectively shape or direct the device end. Likewise, a shaped catheter or sheath can be employed for such purposes.

Other device articulation options for selecting the angular orientation of the funnel-trap portion of the device are possible as well. Any of a variety of steerable or directable catheter-type technologies (reliant on pull-wires or otherwise) can be incorporated in shaft <NUM> for such purposes. Examples include the mechanisms described in USPNs <NUM>,<NUM>,<NUM>; <NUM>,<NUM>,<NUM>; <NUM>,<NUM>,<NUM> and <NUM>,<NUM>,<NUM>.

The "funnel trap" may be generally frusto-conical in shape as shown or otherwise configured. With an outer conical shape (i.e., a triangular shape in cross section as shown in <FIG>) the structure is highly supportive for any necessary or desirable tissue discretion that might need to occur to free an emplaced filter. Moreover, such a shape provides a flexible "waist" section <NUM> for the directable feature(s) noted above. Still, the device may be bowed outward along its sides or otherwise configured without departing from claimed inventive aspects of variations.

Importantly, the distal rim opening <NUM> of the structure is larger than the more proximal rim opening or aperture <NUM> to operate in guiding filter engagement feature(s) or enlargement <NUM>/<NUM>' (as shown) past the proximal opening or aperture into a pocket (P) where it is captured and subsequently locked upon advancing sleeve <NUM>.

Such a pocket is formed between braid walls <NUM> and bend or fold <NUM> in the braid, for which the fold optionally serves as an abutment feature with an edge or shoulder of nub bin/bump <NUM>/<NUM>' when the funnel trap section <NUM> is compressed or collapsed. To ensure capture, the sleeve <NUM> may be advanced fully over trap <NUM> before withdrawal into a separate catheter. In other words, in some embodiments, advancing sleeve <NUM> over funnel section <NUM> "closes the trap" and securely captures the implant to be retrieved.

Sleeve <NUM> may be a dedicated part of system <NUM> or it may be a catheter or so-called jugular access sheath. After the medical device (as in the illustrated case a temporary IVC filter) is covered by advancing the sleeve <NUM> over it, then - typically - the medical device is retrieved by withdrawal into this sleeve, catheter or sheath <NUM> or another catheter (not shown). Any or all such activity may be visualized fluoroscopically by a physician by way of marker features <NUM>/<NUM>' and <NUM> and/or others as may be conveniently provided.

Notably, system <NUM> may be used identically when capturing a filter <NUM> with a typical hook end <NUM>. However, the additional bulk/lateral extension of the hook may necessitate use of a relatively larger sleeve or catheter <NUM> for locking.

In the various system architectures, the catheter/pusher shaft <NUM>, sleeve <NUM> or other catheters or sheaths used in or with the system may comprise a simple extrusion (e.g., PTFE, FEP, PEEK, PI, etc.) or may be constructed using conventional catheter construction techniques and include a liner, braid support and outer jacket (not shown), metal hypotube, etc. Further, the filter frame may be constructed using conventional laser cutting and electropolishing techniques and/or be otherwise constructed. In embodiments intended for tracking through a guide/delivery catheter without an incorporated sheath, a loading sheath may be employed. Any such loading sheath may be splittable. Other typical percutaneous access instruments (such as wires, etc.), valves and other hardware may also be employed in connection with the invention embodiments, including medical treatment methods.

The funnel-trap structure <NUM> can be made as a subassembly and attached to its catheter/pusher shaft <NUM>. PCT publication <CIT> (<CIT>) and <CIT>, each detail optional steps in the manufacture of a braid preform of the funnel-trap portion <NUM> of the final device as shown in <FIG>.

Here, inner and outer layers of braid <NUM> are shown heatset using conventional techniques (e.g., in a furnace, salt pot, etc.) in a funnel shape with distal bends <NUM> in the braid wire forming an outer rim <NUM> with a large(r) distal opening or aperture. Inner or proximal bends <NUM> form an inner rim <NUM> with a small( er) more proximal opening or aperture. Stated otherwise, the braid used to construct the funnel-shape trap is folded back (e.g., in a flap <NUM>) at the distal opening to provide a more proximal opening or aperture. Likewise, the braid is folded over or back to define the proximal opening or aperture.

For IVC filter retrieval, the funnel-trap portion <NUM> shown may have a diameter (D) from about <NUM> to about <NUM>, or more preferably about <NUM> to about <NUM> (i.e., size in a range to work within average size human IVCs where such vessels are reported as having a mean diameter of <NUM> within a range of <NUM> to <NUM>). A length (L) may range from about <NUM> to about <NUM>. An overall cone angle (a) between braid walls <NUM> may be between about <NUM> and about <NUM> degrees. An angle W) of bend <NUM> between braid wall <NUM> and flap <NUM> may be between about <NUM> and about <NUM> degrees and flap length (F) may be between about <NUM> and about <NUM> in length. Overall, an opening diameter (d) may be between about <NUM> and about <NUM> percent of diameter (D) depending on the selected combination of the noted variables (i.e., d, D, L, F, α and β). At the lower end of this range, the inner "opening" may be substantially closed such that it must be pushed-open to receive the proximal engagement feature(s) of the implant during retrieval. At the higher end of the range, the flap may lie completely along or in-line with the outer layer(s) of the device. The configuration selected will depend upon the type of capture approach selected as further detailed herein. The opening <NUM> of the funnel trap may be set perpendicular relative to a device axis (A) as shown. Otherwise, it may be angled or have a more complex shape as described in connection with the above-referenced <CIT>.

As shown in <FIG>, embodiments hereof may include a support member <NUM> including elongate members 112a, 112b, etc. set within the funnel trap section or portion of the device to support distal rim <NUM>. This example shown in cross section may have eight such elongate members connected with four each to a nested or stacked hub portion (not shown). The support member(s) may alternatively or additionally be interposed between braid layers <NUM>, <NUM>'. Further details of possible support member constructions and/or placements are set forth in PCT Patent Application No. <CIT> and <CIT>, both of which are titled 'TVC Filter Retrieval Systems with Interposed Support Members,".

In <FIG>, the system <NUM> shown includes components as discussed above along with the addition of a line, fiber, filament, fibril, thread, yam or strand <NUM> serving as a tether <NUM>. In one example, the strand element <NUM> (as a yarn or thread) is provided as a braided or plaited suture material. Ultra-high-molecular-weight polyethylene (UHMWPE) suture material may be selected for such purpose based on its strength, limited stretch and biocompatible characteristics. Other polymer fiber or metal filament (e.g., Nitinol) options are possible as well.

In any case, the tether can serve any number of purposes. In one example, the tether may hold or stabilize the inner flap <NUM> from pulling out or everting if the medical device <NUM> to be captured is one that includes a hook interface <NUM>. A hook <NUM> can be captured by the funnel trap structure upon passing into or though the proximal rim opening <NUM>. The hook may catch on a crossing filament as discussed further below or along the rim. For such purpose, the rim is supported or supplemented with a ring <NUM> interposed between braid layers <NUM>/<NUM>'. The ring may be defined by a portion of the strand <NUM> as further described below or otherwise.

In another example, the tether <NUM> may be used for actuation of the rim opening or aperture <NUM>. When the ring <NUM> is in the form of a synchable loop or lasso as part of the strand, the tether portion <NUM> of the strand can be used to close the associated aperture <NUM>. (Examples of such loop or lasso constructions are discussed further below).

The tether may be actuated (e.g., pulled) using a handle interface (e.g., as shown in <FIG>). Alternatively, the tether may be affixed anywhere proximal to the funnel trap section <NUM> and still be used to close a lasso interface for medical device capture. Even if attached at or adjacent to point (A) in <FIG>, when sheath <NUM> is advanced as shown over the funnel trap section <NUM>, the braid defining the funnel trap collapses or compresses with the angle of its included wires changing. This causes the funnel section to lengthen. With the tether position fixed, it effectively "pulls" on any lasso member included at the proximal aperture closing it. All such action is indicated by arrow sets <NUM>, <NUM>, <NUM> in <FIG>.

The so-called lasso may be included at an intermediate stage of production of the system <NUM>. <FIG> shows a loop or lasso <NUM> configuration as further described in connection with <FIG>. While the loop <NUM> strand may be threaded into place at the wire bend or fold <NUM>, it is more efficiently installed by pulling apart or folding back braid layer <NUM> and <NUM>' and inserting it there between. Then, the braid configuration shown is flipped back so that flap section <NUM> is once again inset within the (optionally) conical shape of the funnel.

As shown in <FIG>, a loop pattern <NUM> is formed that includes a ring <NUM> and two exit legs or lengths 222a, 222b. These lengths may extend substantially as indicated by the arrows and used as tether members, tied-off to one another and trimmed, one may be tied-off to another and trimmed with the other used at a longer length, etc..

In <FIG>, loop pattern <NUM> is set in place between braid layers <NUM>, <NUM>' with its two ends 222a, 222b exiting the same space or nearby spaces in the braid as shown. Pulled as a tether <NUM>, loop <NUM> inside aperture <NUM> is synched or closed down (as indicated by arrows <NUM> and <NUM>, respectively).

Another approach in defining a synchable loop is to use a slipknot or eyelet in the strand so that a single entry/exit member can be used passing through the braid. <FIG> is a side view of a portion of a suture or other fiber strand <NUM> setup for splicing-in such an eyelet. Sometimes the type of splice <NUM> to be constructed with the setup shown is referred to as a "long buried" splice. With hollow braided (in this case) suture material, an elongate tail <NUM> section of the material can be drawn through a splice channel <NUM> opened in the strand of material to define an eye or eyelet region <NUM>. A needle or wire tool <NUM> may be used to draw the tail through the body of the strand <NUM>.

With a ratio of splice length (SL) to strand diameter ( d) of about <NUM><NUM> to <NUM> times or greater, (i.e., SL in the case of the suture material described below of about <NUM> to <NUM> long) splice strength on par with the native material can be achieved. For added security, the splice channel or section <NUM> can be further stabilized by biocompatible glue, laser welding or heat staking. Still further, any remaining tail <NUM> length of the splice can be melt-formed into a ball (not shown) that will not pull through the braided body. Other variations in the splicing procedure may include removing a number of filaments from the tail section to reduce the splice bulk. However, when dealing with fine suture (e.g., on the order of about <NUM> to about <NUM> inches (or about <NUM> to about <NUM>) in diameter with as few as <NUM> or <NUM> braided threads as advantageously used in embodiments hereof) such activity may be avoided.

Referring specifically to <FIG>, it illustrates loop pattern <NUM> constructed with such a splicing approach. A single strand <NUM> passes through the eyelet <NUM> formed by splicing. The end length <NUM> may serve for a tether or other features as further described.

<FIG> shows a loop pattern or approach <NUM> where an eyelet <NUM> is formed by splitting or passing the strand <NUM> through itself The end of the strand opposite any retained end length <NUM> may be tied-off by a knot, weld or glue bead <NUM>.

<FIG> presents yet another loop or lasso pattern <NUM>. Here, two strands 210a and 210b are provided to encircle a funnel aperture <NUM>. This approach may offer improved syncing around the fold <NUM> in which it may be placed. However, with as many as four tether ends 222a-222d to manage for assembly, other options may be preferred.

<FIG> is an end view of a funnel trap <NUM> variation that may include a ring <NUM>, optionally in the form of a synchable loop or lasso. Such a construction may be placed between braid layers <NUM>/<NUM>'. Or at least one strand <NUM> may be used to define a cross-hairs type structure <NUM>. More generally, one, two or more aperture crossing strands may be installed or threaded through or with the braid to serve as a filter hook <NUM> capture interface.

With multiple crossing strands or members, a "web" for implant capture may be defined. The web may use regularly (i.e., consistently) spaced members. Or it may be asymmetrical. The web may include two segments crossing in an "X" pattern (e.g., as shown in <FIG>). Another example may have three segments defining a "Y" shape. Yet another example pattern is in the shape of a trefoil knot. Still others options are possible as well.

Particular tying or threading patterns for X- or crossing-type webs are presented in <FIG>. A simple cross or X type interface (i.e., without a surrounding loop or ring) may be constructed with a pattern <NUM> as show in <FIG>. As sort of a figure-eight threading pattern through the braid (with crossing sections 212a and 212b and curve or turn sections 214a, 214b) set between or outside braid layers <NUM>, <NUM>' includes two end lengths (222a, 222b ). These may be tied off to one another in a knot (not shown), they may pass proximally to a tie-off or glue-in point, or be otherwise managed or handled.

<FIG> illustrates an example of a proximal end glue-in attachment point or zone (B) where shaft <NUM> includes ports 34a-34f. These ports may receive adhesive for an improved physical lock with shaft body and/or simply provide visual indication of formation of an adequate length glue joint to hold tether member(s) securely within the shaft.

<FIG> shows an alternative tie pattern for a loop and crosshair arrangement <NUM>. The loop or ring <NUM> defined (when placed between braid layers) supports any filter (or other implant) hook received in or around the rim of the funnel trap device. With such a ring in place, a hook cannot simply pull through a number of captured or entrained braid filaments (a consideration when using fine Nitinol or other filaments in the braid). Rather, the hook would have to pull past the strand <NUM> itself (which is also supported by braid all around). Regardless, the hook may sometimes instead catch or locate upon the crossing members 212a, 212b of the pattern. They are supported from pull-out by the ends 222a, 222b that may be secured to one another by tying or otherwise as per variations discussed above.

As for other details of pattern <NUM>, note the looping-around or intertwining of strand sections indicated at (C) that may assist in providing a more stable loop structure. Also, note the center region in which the horizontal member 212b (as oriented in the view) appears to cross over the vertical member 212a, and the strand portion adjacent extensions 222a under adjacent loop <NUM> section. Such up/down or over/under weaving may advantageously be employed to control strand portion position or placement within the finally constructed device.

Similar or related weaving is shown for pattern <NUM> shown in <FIG>. What differs primarily here is the use of a strand <NUM> with a splice <NUM> and splice-defined eyelet <NUM> so that a structure similar to that in <FIG> can be produced with a single end <NUM> where this end may ultimately serve as a tether or be tied-off at the aperture (to the strand, adjacent braid or otherwise).

Referring again <FIG>, it provides a side sectional view of a retrieval system embodiment <NUM> including crossing member(s) <NUM>, a ring <NUM> around proximal opening rim <NUM>, and an optional tether(s) <NUM>. The tether glue-in approach illustrated has already been discussed. Also noteworthy is the manner in which the setup is configured to release the tether if disengagement of a/the filter is desired. Simply by cutting shaft <NUM>, the tether <NUM> is released and can be pulled free of filter hook <NUM> engagement. In another arrangement, a plug <NUM> may be used to secure or hold the tether in place in system <NUM> (or system <NUM>) until removed. The plug may be press fit (lightly so as to allow removal), threaded or held with a detent <NUM> in place. A textured or knurled grip <NUM> may be provided for user-interface purposes. Other options are possible as well.

But once the plug is pulled or the shaft is cut, tether <NUM> is released. Especially when a spliced-eyelet tether is used with its loop or ring set between braid layers, such release does not risk losing the tether strand <NUM> altogether from system <NUM> and/or <NUM>.

Also notable is that system <NUM> can advantageously be used to capture a filter <NUM> without a locking catheter (note that none is shown in <FIG>). Still, cover and withdrawal of any captured IVC filter will commonly be accomplished in connection with a commercially available catheter or sheath.

Still further, an optional handle <NUM> (indicated by dashed line at small scale) may be included in the system for any desired tether manipulation. With such a handle, an opening interface selected from any of the patterns presented in <FIG>, <FIG> or related may be closed by pulling the tether through handle manipulation (e.g., via a wheel, thumb slide or other user interface feature). Also, the handle may be configured to release tether <NUM> like plug <NUM> described above and/or let-out some portion of tether length (e.g., up to about <NUM> inches or about <NUM> to about <NUM> or more) to allow flap <NUM> and aperture <NUM> eversion for any efforts that may be desired to release a hook <NUM> from the system.

Various methods <NUM> of use can be defined in connection with the subject funnel trap embodiments <NUM>, <NUM> or <NUM> or related medical device hardware. All such methods are not part of the claimed subject matter, but are discussed to aid understanding of the invention. <FIG> is a flow diagram depicting one example embodiment of a method of use. Vascular access, medical imaging and positioning of the selected device adjacent to an implant or foreign body to be retrieved in the patient's vasculature are steps common to the methods. For example, see <NUM> in <FIG>. Such positioning <NUM> is achieved by or after passing the funnel trap device through a sleeve in the form of a vascular access sheath or catheter.

Likewise, at <NUM>, the methods include positioning the funnel trap device over the proximal portion of the element to be captured. In doing so (i.e., for the case of filter retrieval), the proximal capture interface of the filter will pass first through a distal aperture and then through the proximal aperture of the funnel-trap device. Due to the braided construction offered, such passage may be regarded both as protected (i.e., as the implant capture feature of the implant is within the boundary defined by braid) and self-guided (i.e., as the capture feature moves past or along the inner flap section of the funnel trap).

At <NUM>, a number of capture options are possible depending on the system selected for use. Per option <NUM>, the proximal interface may be a hook captured by a crossing member or along the rim interface at the proximal aperture of the funnel trap retrieval device. As another option <NUM>, a loop or lasso feature at the proximal aperture may be synched or tightened around the implant capture feature (be it a hook or other enlarged portion of an IVC filter). As yet another option <NUM> (i.e., in connection with advancing a locking sheath or catheter), the implant capture feature may be secured within a pocket of the device at or adjacent to the aperture and its nm.

After any such action, a/the catheter is typically advanced to cover the IVC filter at <NUM>. During such advancement, tissue may separate from the body or legs of the filter (i.e., if this is the type of implant being capture, other possibilities include lost or stray embolization coils, part of a Central Venous Catheter (CVC) or line, etc ). Finally, at <NUM>, the filter (or other medical device) is withdrawn through a catheter.

Both the advancement to cover the implant (or other device to be retrieved or recovered) and withdrawal may take place in connection with one catheter. However, when a separate locking catheter is provided (e.g., in connection with system <NUM> for the approach in <NUM>) an inner locking catheter will typically be what is advanced over the implant or device to be retrieved, and it will be withdrawn - together with the implant or device retrieved - out through an outer access catheter or sheath (i.e., the catheter or sheath originally used to achieve vascular access).

Clearly, a single-catheter approach can save procedure and/or fluoroscopy time. Systems <NUM> and <NUM> may be better suited to realize such advantages in view of their additional implant or device (e.g., IVC filter) capture features they possess as variously described above. However, each of the system embodiments described herein presents its own unique advantages that argue for its use and clinical relevance and/or adoption, especially in comparison to known retrieval devices and approaches.

The subject methods, including methods of use and/or manufacture are not part of the claimed subject matter, and may be carried out in any order of the events which is logically possible, as well as any recited order of events.

Methods may include any of a hospital staffs activities associated with device provision, implant positioning, re-positioning, implant or device retrieval and/or release.

Furthermore, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in the stated range is encompassed within the invention.

Claim 1:
Retrieval apparatus (<NUM>, <NUM>, <NUM>) for a vascular medical device, the apparatus comprising:
an elongate shaft (<NUM>) having an axis having a flexible distal extension comprising braid (<NUM>), the distal extension folded-back inwardly to form a distal opening (<NUM>) and a proximal opening (<NUM>), the proximal opening sized to receive a portion of the medical device therethrough for securing the medical device, characterised in that the apparatus further comprises:
at least one a ring member (<NUM>) positioned between two layers of the braid (<NUM>, <NUM>') encircling the proximal opening.