Abstract:
Funnel-trap type delivery and/or retrieval devices for temporary Inferior Vena Cava (IVC) filters or other medical implants or foreign bodies are described. These may employ a locking sheath or a proximal-aperture capture feature or features for IVC filter (or other device) retrieval.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of International Patent Application PCT/US2014/042343 filed Jun. 13, 2014, which claims priority to U.S. Provisional Application No. 61/835,295 filed Jun. 14, 2013, all of which are incorporated by reference herein in their entirety and for all purposes. 
     
    
     FIELD 
       [0002]    The embodiments described herein relate to endovascular temporary Inferior Vena Cava (IVC) filter, other implant or other foreign body retrieval devices or system and methods. 
       BACKGROUND 
       [0003]    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. 
         [0004]    While retrieval is a simple procedure in principle, difficulty is often encountered capturing a filter&#39;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. 
       SUMMARY 
       [0005]    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 U.S. Pat. Nos. 3,952,747; 5,601,595; 6,443,972; 7,338,512 and 7,625,390 (all of which patents are incorporated herein by reference in their entireties for any purpose), with commercially available devices including the OPTEASE, GUNTHER TULIP, CELECT and OPTION or others. 
         [0006]    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). 
         [0007]    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 nubbin 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. 
         [0008]    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 vivo or ex vivo) are all included within the scope of the present disclosure. Some aspects of the same are described above, and more detailed discussion is presented in connection with the figures below. 
         [0009]    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. It is intended that all such additional systems, devices, methods, features and advantages be included within this description, be within the scope of the subject matter described herein, and be protected by the accompanying claims. In no way should the features of the example embodiments be construed as limiting the appended claims, absent express recitation of those features in the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    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. 
           [0011]      FIGS. 1A and 1B  picture IVC filter variations as may be used in the present system. 
           [0012]      FIG. 2  is a side view of a delivery and/or retrieval system with an end of any type of implantable medical device or foreign body. 
           [0013]      FIG. 3  is a side-sectional view of a converted preform (i.e., a finally shaped funnel section of the subject device) after heatsetting. 
           [0014]      FIG. 4  is a partial side-sectional view of retrieval system embodiment including a loop and tether. 
           [0015]      FIG. 5  is a side view of a partially inverted preform and associated tether or loop. 
           [0016]      FIG. 6  is a side view of a portion of a tether and setup for splicing. 
           [0017]      FIGS. 7A-7D  are top or end view illustrations of various loop and tether construction options. 
           [0018]      FIG. 8  is an end view of a funnel trap with crossing member and tether installed. 
           [0019]      FIGS. 9A-9C  are top or end view illustrations of various crossing member and tether construction options. 
           [0020]      FIG. 10  is a side sectional view of a retrieval system embodiment including crossing member(s) and an optional tether. 
           [0021]      FIG. 11  is a flow diagram depicting an example embodiment of a method of use. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    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 devices, systems and methods. Various changes may be made to these embodiments and equivalents may be substituted without departing from the true spirit and scope of the various embodiments. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s) to the objective(s), spirit or scope of the present invention. All such modifications are intended to be within the scope of the claims made herein. 
         [0023]    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. 
         [0024]    All features, elements, components, functions, and steps described with respect to any embodiment provided herein are intended to be freely combinable and substitutable with those from any other embodiment. If a certain feature, element, component, function, or step is described with respect to only one embodiment, then it should be understood that that feature, element, component, function, or step can be used with every other embodiment described herein unless explicitly stated otherwise. This paragraph therefore serves as antecedent basis and written support for the introduction of claims, at any time, that combine features, elements, components, functions, and steps from different embodiments, or that substitute features, elements, components, functions, and steps from one embodiment with those of another, even if the following description does not explicitly state, in a particular instance, that such combinations or substitutions are possible. Express recitation of every possible combination and substitution is overly burdensome, especially given that the permissibility of each and every such combination and substitution will be readily recognized by those of ordinary skill in the art upon reading this description 
         [0025]      FIG. 1A  shows a GUNTHER TULIP (Cook Medical, Inc.) temporary IVC filter  10  with a hook  12  end interface for retrieval. As shown in  FIG. 1B  for a IVC filter  20 , the hook may be modified or substituted for a nubbin-type interface  22 . The nubbin (itself) may comprise a laser-formed or solder-formed protuberance or bump  24  on an extension  26  from a hub  28 . Alternatively, as shown in  FIG. 2 , a/the filter retrieval interface  22  may comprise a band  24 ′ (e.g., a Pt marker band) mounted (e.g., by swaging, welding, gluing, etc.) on a/the extension  26 . However the enlargement is created, the funnel-trap structures described below are adapted to secure that feature for IVC filter retrieval. 
         [0026]      FIG. 2  provides an overview of the subject system  100 . A funnel-trap structure  30  is shown made of heatset braid material  32 . The construction provides a flexible distal extension to an elongate shaft  34 . The shaft is received within an elongate sleeve  50  (that may be a commercially available catheter or sheath or a custom part of the overall system  100 ) and may include a distal radiopaque marker band  52 . 
         [0027]    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 72 and 288, or between about 144 and 192 filament “ends” in a 1-over-1, 1-over-2, 2-over-2 or other pattern. With (superelastic) Nitinol, the wire is advantageously between about 0.001 and about 0.003 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. 
         [0028]    To assist with target device capture or recapture, the funnel trap structure  30  may be selectably directable. As indicated by the arrows in  FIG. 2 , 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  34  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. 
         [0029]    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  34  for such purposes. Examples include the mechanisms described in U.S. Pat. Nos. 4,723,936; 4,960,411; 6,251,092 and 8,273,073 each incorporated herein by reference in its entirety for such description. 
         [0030]    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. 3 ) 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  48  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 or variations. 
         [0031]    Importantly, the distal rim opening  40  of the structure is larger than the more proximal rim opening or aperture  42  to operate in guiding filter engagement feature(s) or enlargement  24 / 24 ′ (as shown) past the proximal opening or aperture into a pocket (P) where it is captured and subsequently locked upon advancing sleeve  50 . 
         [0032]    Such a pocket is formed between braid walls  44  and bend or fold  38  in the braid, for which the fold optionally serves as an abutment feature with an edge or shoulder of nubbin/bump  24 / 24 ′ when the funnel trap section  30  is compressed or collapsed. To ensure capture, the sleeve  50  may be advanced fully over trap  30  before withdrawal into a separate catheter. In other words, in some embodiments, advancing sleeve  50  over funnel section  30  “closes the trap” and securely captures the implant to be retrieved. 
         [0033]    Sleeve  50  may be a dedicated part of system  100  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  50  over it, then—typically—the medical device is retrieved by withdrawal into this sleeve, catheter or sheath  50  or another catheter (not shown). Any or all such activity may be visualized fluoroscopically by a physician by way of marker features  24 / 24 ′ and  52  and/or others as may be conveniently provided. 
         [0034]    Notably, system  100  may be used identically when capturing a filter  10  with a typical hook end  12 . However, the additional bulk/lateral extension of the hook may necessitate use of a relatively larger sleeve or catheter  50  for locking. 
         [0035]    In the various system architectures, the catheter/pusher shaft  34 , sleeve  50  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. 
         [0036]    The funnel-trap structure  30  can be made as a subassembly and attached to its catheter/pusher shaft  34 . PCT publication PCT/US2014/042343 (WO2014201380) and U.S. patent application Ser. No. 14/569,500, each incorporated by reference in its entirety detail optional steps in the manufacture of a braid preform of the funnel-trap portion  30  of the final device as shown if  FIG. 3 . 
         [0037]    Here, inner and outer layers of braid  32  are shown heatset using conventional techniques (e.g., in a furnace, salt pot, etc.) in a funnel shape with distal bends  36  in the braid wire forming an outer rim  40  with a large(r) distal opening or aperture. Inner or proximal bends  38  form an inner rim  42  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  46 ) 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. 
         [0038]    For IVC filter retrieval, the funnel-trap portion  30  shown may have a diameter (D) from about 5 mm to about 20 mm, or more preferably about 10 to about 15 mm (i.e., size in a range to work within average size human IVCs where such vessels are reported as having a mean diameter of 20 mm within a range of 13 to 30 mm). A length (L) may range from about 10 mm to about 30 mm. An overall cone angle (α) between braid walls  44  may be between about 30 and about 90 degrees. An angle (β) of bend  36  between braid wall  44  and flap  46  may be between about 0 and about 60 degrees and flap length (F) may be between about 1 and about 10 mm in length. Overall, an opening diameter (d) may be between about 5 and about 95 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 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  40  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 U.S. patent application Ser. No. 14/569,500 incorporated herein by reference. 
         [0039]    As shown in  FIG. 4 , embodiments hereof may include a support member  110  including elongate members  112   a,    112   b,  etc. set within the funnel trap section or portion of the device to support distal rim  40 . 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  32 ,  32 ″. Further details of possible support member constructions and/or placements are set forth in PCT Patent Application No. PCT/US15/65025 and U.S. patent application Ser. No. 14/965,500, both of which are titled “IVC Filter Retrieval Systems with Interposed Support Members,” and both of which are incorporated by reference herein in their entireties and for all purposes. 
         [0040]    In  FIG. 4 , the system  200  shown includes components as discussed above along with the addition of a line, fiber, filament, fibril, thread, yarn or strand  210  serving as a tether  220 . In one example, the strand element  210  (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. 
         [0041]    In any case, the tether can serve any number of purposes. In one example, the tether may hold or stabilize the inner flap  46  from pulling out or everting if the medical device  10  to be captured is one that includes a hook interface  12 . A hook  12  can be captured by the funnel trap structure upon passing into or though the proximal rim opening  42 . The hook may catch on a crossing filament as discussed further below or along the rim. For such purpose, the rim may be supported or supplemented with a ring  230  interposed between braid layers  32 / 32 ′. The ring may be defined by a portion of the strand  210  as further described below or otherwise. 
         [0042]    In another example, the tether  220  may be used for actuation of the rim opening or aperture  42 . When the ring  230  is in the form of a synchable loop or lasso as part of the strand, the tether portion  220  of the strand can be used to close the associated aperture  42 . (Examples of such loop or lasso constructions are discussed further below). 
         [0043]    The tether may be actuated (e.g., pulled) using a handle interface (e.g., as shown in  FIG. 10 ). Alternatively, the tether may be affixed anywhere proximal to the funnel trap section  30  and still be used to close a lasso interface for medical device capture. Even if attached at or adjacent to point (A) in  FIG. 4 , when sheath  50  is advanced as shown over the funnel trap section  30 , 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 1, 2, 3 in  FIG. 4 . 
         [0044]    The so-called lasso may be included at an intermediate stage of production of the system  200 .  FIG. 5  shows a loop or lasso  232  configuration as further described in connection with  FIGS. 7A . While the loop  230  strand may be threaded into place at the wire bend or fold  38 , it is more efficiently installed by pulling apart or folding back braid layer  32  and  32 ′ and inserting it there between. Then, the braid configuration shown is flipped back so that flap section  46  is once again inset within the (optionally) conical shape of the funnel. 
         [0045]    As shown in  FIG. 7A , a loop pattern  232  is formed that includes a ring  230  and two exit legs or lengths  222   a,    222   b.  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. 
         [0046]    In  FIG. 5 , loop pattern  232  is set in place between braid layers  32 ,  32 ′ with its two ends  222   a,    222   b  exiting the same space or nearby spaces in the braid as shown. Pulled as a tether  220 , loop  230  inside aperture  42  is synched or closed down (as indicated by arrows 5 and 3, respectively). 
         [0047]    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. 6  is a side view of a portion of a suture or other fiber strand  210  setup for splicing-in such an eyelet. Sometimes the type of splice  240  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  242  section of the material can be drawn through a splice channel  244  opened in the strand of material to define an eye or eyelet region  246 . A needle or wire tool  248  may be used to draw the tail through the body of the strand  210 . 
         [0048]    With a ratio of splice length (SL) to strand diameter (d) of about 35 to 70 times or greater, (i.e., SL in the case of the suture material described below of about 5 to 6 mm long) splice strength on par with the native material can be achieved. For added security, the splice channel or section  244  can be further stabilized by biocompatible glue, laser welding or heat staking. Still further, any remaining tail  242  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 0.008 to about 0.012 inches (or about 0.2 to about 0.3 mm) in diameter with as few as 6 or 8 braided threads as advantageously used in embodiments hereof) such activity may be avoided. 
         [0049]    Referring specifically to  FIG. 7B , it illustrates loop pattern  234  constructed with such a splicing approach. A single strand  210  passes through the eyelet  246  formed by splicing. The end length  222  may serve for a tether or other features as further described. 
         [0050]      FIG. 7C  shows a loop pattern or approach  236  where an eyelet  248  is formed by splitting or passing the strand  210  through itself. The end of the strand opposite any retained end length  222  may be tied-off by a knot, weld or glue bead  250 . 
         [0051]      FIG. 7D  presents yet another loop or lasso pattern  236 . Here, two strands  210   a  and  210   b  are provided to encircle a funnel aperture  42 . This approach may offer improved syncing around the fold  38  in which it may be placed. However, with as many as four tether ends  222   a - 222   d  to manage for assembly, other options may be preferred. 
         [0052]      FIG. 8  is an end view of a funnel trap  30  variation that may include a ring  230 , optionally in the form of a synchable loop or lasso. Such a construction may be placed between braid layers  32 / 32 ′. Or at least one strand  210  may be used to define a cross-hairs type structure  260 . 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  12  capture interface. 
         [0053]    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. 8 ). 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. 
         [0054]    Particular tying or threading patterns for X- or crossing-type webs are presented in  FIGS. 9A-9C . A simple cross or X type interface (i.e., without a surrounding loop or ring) may be constructed with a pattern  262  as show in  FIG. 9A . As sort of a figure-eight threading pattern through the braid (with crossing sections  212   a  and  212   b  and curve or turn sections  214   a,    214   b ) set between or outside braid layers  32 ,  32 ′ includes two end lengths ( 222   a,    222   b ). 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. 
         [0055]      FIG. 10  illustrates an example of a proximal end glue-in attachment point or zone (B) where shaft  34  includes ports  34   a - 34   f  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. 
         [0056]      FIG. 9B  shows an alternative tie pattern for a loop and crosshair arrangement  264 . The loop or ring  230  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  210  itself (which is also supported by braid all around). Regardless, the hook may sometimes instead catch or locate upon the crossing members  212   a,    212   b  of the pattern. They are supported from pull-out by the ends  222   a,    222   b  that may be secured to one another by tying or otherwise as per variations discussed above. 
         [0057]    As for other details of pattern  264 , 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  214   b  (as oriented in the view) appears to cross over the vertical member  214   a,  and the strand portion adjacent extensions  222   a  under adjacent loop  230  section. Such up/down or over/under weaving may advantageously be employed to control strand portion position or placement within the finally constructed device. 
         [0058]    Similar or related weaving is shown for pattern  266  shown in  FIG. 9C . What differs primarily here is the use of a strand  210  with a splice  240  and splice-defined eyelet  248  so that a structure similar to that in  FIG. 9B  can be produced with a single end  222  where this end may ultimately serve as a tether or be tied-off at the aperture (to the strand, adjacent braid or otherwise). 
         [0059]    Referring again  FIG. 10 , it provides a side sectional view of a retrieval system embodiment  300  including crossing member(s)  212 , a ring  230  around proximal opening rim  42 , and an optional tether(s)  220 . 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  34 , the tether  210  is released and can be pulled free of filter hook  12  engagement. In another arrangement, a plug  310  may be used to secure or hold the tether in place in system  300  (or system  200 ) until removed. The plug may be press fit (lightly so as to allow removal), threaded or held with a detent  312  in place. A textured or knurled grip  314  may be provided for user-interface purposes. Other options are possible as well. 
         [0060]    But once the plug is pulled or the shaft is cut, tether  210  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  210  altogether from system  200  and/or  300 . 
         [0061]    Also notable is that system  300  can advantageously be used to capture a filter  10  without a locking catheter (note that none is shown in  FIG. 10 ). Still, cover and withdrawal of any captured IVC filter will commonly be accomplished in connection with a commercially available catheter or sheath. 
         [0062]    Still further, an optional handle  320  (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  FIGS. 7A-7D, 9A-9C  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  210  like plug  310  described above and/or let-out some portion of tether length (e.g., up to about 0.5 inches or about 10 mm to about 15 mm or more) to allow flap  46  and aperture  42  eversion for any efforts that may be desired to release a hook  12  from the system. 
       Methods 
       [0063]    Various methods  400  of use can be defined in connection with the subject funnel trap embodiments  100 ,  200  or  300  or related medical device hardware.  FIG. 11  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&#39;s vasculature are steps common to the methods. For example, see  410  in  FIG. 11 . Such positioning  410  is achieved by or after passing the funnel trap device through a sleeve in the form of a vascular access sheath or catheter. 
         [0064]    Likewise, at  420 , 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). 
         [0065]    At  430 , a number of capture options are possible depending on the system selected for use. Per option  432 , 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  434 , 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  436  (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 rim. 
         [0066]    After any such action, a/the catheter is typically advanced to cover the IVC filter at  440 . 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  450 , the filter (or other medical device) is withdrawn through a catheter. 
         [0067]    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  100  for the approach in  434 ) 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). 
         [0068]    Clearly, a single-catheter approach can save procedure and/or fluoroscopy time. Systems  200  and  300  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. 
       Variations 
       [0069]    The subject methods, including methods of use and/or manufacture, may be carried out in any order of the events which is logically possible, as well as any recited order of events. Embodiment methods may include any of a hospital staffs activities associated with device provision, implant positioning, re-positioning, implant or device retrieval and/or release. 
         [0070]    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. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. 
         [0071]    Though the invention has been described in reference to several examples, optionally incorporating various features, the invention is not to be limited to that which is described or indicated as contemplated with respect to each variation of the invention. Various changes may be made to the invention described and equivalents (whether recited herein or not included for the sake of some brevity) may be substituted without departing from the true spirit and scope of the invention. 
         [0072]    Reference to a singular item includes the possibility that there are a plurality of the same items present. More specifically, as used herein and in the appended claims, the singular forms “a,” “an,” “said,” and “the” include plural referents unless specifically stated otherwise. In other words, use of the articles allow for “at least one” of the subject item in the description above as well as the claims below. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. 
         [0073]    Without the use of such exclusive terminology, the term “comprising” in the claims shall allow for the inclusion of any additional element—irrespective of whether a given number of elements are enumerated in the claim, or the addition of a feature could be regarded as transforming the nature of an element set forth in the claims. Except as specifically defined herein, all technical and scientific terms used herein are to be given as broad a commonly understood meaning as possible while maintaining claim validity. Accordingly, the breadth of the different inventive embodiments or aspects described herein is not to be limited to the examples provided and/or the subject specification, but rather only by the scope of the issued claim language.