CA2940038A1 - Vena cava filter with filament - Google Patents

Abstract

A vena cava filter is described, having one or more frame members or an elongated member arranged in helical fashion. A plurality of filaments connect frame members or portions of the elongated member. The filaments may be made of suture material. Hooks may be placed on a free end of the filaments, along the length thereof, or on one or more frame members to engage the blood vessel wall and anchor the filter. A retrieval member may be positioned on the filter to facilitate withdrawal of the filter from the blood vessel.

Description

VENA CAVA FILTER WITH FILAMENT
BACKGROUND

[0002] Inferior vena cava (IVC) filters are devices configured for insertion into the inferior vena cava to capture particles that may be present in the blood stream which, if transported to, for example, the lungs could result in serious complications and even death.
Typically, IVC filters are utilized in patients who have a contraindication to anticoagulation or in patients developing clinically apparent deep vein thrombosis (DVT) and/or pulmonary embolism (PE). Patients who have recently suffered from trauma, have experienced a heart attack (myocardial infarction), or who have undergone major surgical procedure (e.g., surgical repair of a fractured hip, etc.) may develop clinically apparent DVT. When a thrombus clot loosens from the site of formation and travels to the lung, it may cause PE, a life-threatening condition. An IVC filter may be placed in the circulatory system to intercept one or more clots and prevent them from entering the lungs. IVC filters are either permanent or retrievable.

[003] There are many different configurations for IVC filters, including those that include a central hub from which extend a plurality of struts that form filter baskets having a conical configuration, such as disclosed in USPN 6,258,026. Other IVC filter configurations utilize wires and/or frame members to form straining devices that permit flow of blood while trapping larger particles. IVC filters are generally configured for compression into a small size to facilitate delivery into the inferior vena cava and subsequent expansion into contact with the inner wall thereof. The IVC filter may later be retrieved from the deployed site by compressing the legs, frame members, etc., depending on the filter configuration.
Typically, an IVC filter will include hooks or anchoring members for anchoring the filter in position within the inferior vena cava. The hooks may be more elastic than the legs or frame members to permit the hooks to straighten in response to withdrawal forces, which facilitate withdrawal from the endothelium layer of the blood vessel without risk of significant injury to the vessel wall.

[0004] Applicants have recognized that it would be desirable to provide an IVC filter that incorporates one or more filaments, such that the filament(s) provide a framing function and/or a filtering function, in order to provide advantageous properties to the IVC
filter. Embodiments of such IVC filters are described herein.
BRIEF SUMMARY OF THE INVENTION

[0005] Accordingly, implantable medical devices with one or more filaments are described herein. In one embodiment, an implantable medical device includes a continuous generally circular member defining a frame having an open interior portion, and a plurality of filaments attached to the frame, each filament having a first end connected to the frame at a first point and a second opposite end connected to the frame at a second point different from the first point, the filaments together defining a generally planar mesh-like surface spanning the interior portion of the frame.

[0006] In another embodiment, an implantable medical device includes a support structure having an open proximal end, and one or more filaments attached to the frame to define a generally planar mesh-like surface spanning the open proximal end.

[0007] These and other embodiments, features and advantages will become more apparent to those skilled in the art when taken with reference to the following more detailed description of the invention in conjunction with the accompanying drawings that are first briefly described.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a side perspective view of one embodiment of a filter with frame members.

[0009] FIG. 2A is a side perspective view of another embodiment of a filter with frame members that are adjustable.

[0010] FIG. 2B is a cut-away view of one embodiment of a frame member of FIG. 2A.

[0011] FIG. 2C is a cut-away view of another embodiment of a frame member of FIG.
2A, shown in a collapsed configuration.

[0012] FIG. 2D is a cut-away view of the embodiment of a frame member of FIG. 2C, shown in an expanded configuration.

[0013] FIG. 3 is a side perspective view of an embodiment of a filter with an elongated member.

[0014] FIG. 4 is a perspective view of another embodiment of a filter with a frame member having an open interior portion spanned by a generally planar mesh-like surface.

[0015] FIG. 5A is a perspective side view of another embodiment of a filter with a support structure having an open proximal end spanned by a generally planar mesh-like surface.

[0016] FIG. 5B is a top view of a variation of the embodiment of FIG. 5A.
DETAILED DESCRIPTION OF THE INVENTION

[0017] The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention.

[0018] The filter embodiments discussed below may be used for insertion into the inferior vena cava or other blood vessels or cavities in a mammalian body. As used herein, the term "suture material" means a material that is, or could be, used as a suture thread by a surgeon, including, for example, synthetic polymers, polyglycolic acid (PGA), polydioxanone (PDS), polyglactin, nylon, polypropylene (prolene), silk, catgut, non-absorbable/non-biodegradable materials, and combinations thereof. Included in the term "suture material"
are both monofilantent and multifilament arrangements. Also, as used herein, the term "hook" means a member configured to engage a blood vessel wall which may include, for example, the hooks shown and described in USPN 6,258,026.

[0019] Referring to FIG. 1, one embodiment of a filter is illustrated, Filter 10 includes two or more generally arcuate frame members that are spaced apart and arranged along a longitudinal axis L that extends through two or more frame members. In the embodiment shown, frame member 12 is positioned at a proximal end of filter 10 and frame member 13 is spaced apart from frame member 12 along a longitudinal axis L of the filter. Spaced apart from frame member 13 along longitudinal axis L is frame member 14. The frame members 12, 13, 14 have a generally arcuate shape, which in some embodiments may be circular, elliptical, etc., and which increase in size in the distal direction such that the diameter D12 of frame member 12 is less than the diameter D13 of frame member 13, and the diameter D13 of frame member 13 is less than the diameter D14 of frame member 14. In another embodiment, the diameters of all the frame members are substantially equivalent, while in another embodiment only some of the frame members have diameters that are substantially equivalent. In one embodiment, the frame members decrease in diameter from a proximal end of the filter to a mid-region of the filter and then increase in diameter from the mid-region of the filter to a distal end of the filter. Other embodiments with respect to the shapes and sizes of the frame members in view of the examples provided are also possible and are within the scope of the invention, as one skilled in the art would appreciate. The frame members 12, 13, 14 of filter 10 are shown in an expanded configuration, defining an expanded perimeter of the filter 10. For delivery of the filter 10 to a blood vessel, the frame members 12, 13, 14 are compressed to a collapsed configuration. The frame members 12, 13, 14 in the collapsed configuration define a collapsed perimeter of the filter smaller than the expanded perimeter of the filter 10.

[0020] The frame members (or filaments) may be made of any material typically used for implantable medical devices as known to one skilled in the art, such as, for example, stainless steel, shape memory metals, shape memory alloys, super elastic shape memory metal alloys, metal alloys, shape memory polymers, polymers, and combinations thereof The frame members may also be made of a bio-resorbable material such as, for example, the materials shown and described in USPN 6,287,332; and U.S. Patent Application Publication No.
2002/0004060.

[0021] The generally arcuate frame members 12, 13, 14 of filter 10 are connected together via a plurality of filaments 16. In one embodiment, the filaments 16 include suture material, although in other embodiments, the filaments may include materials discussed above with respect to the frame members. The filaments 16 are attached to each frame member along the longitudinal axis L, as shown in filter 10. However, in other embodiments, the filaments can be attached to every odd frame member along the longitudinal axis L (i.e., the most proximal frame member, the third frame member counting from the proximal frame preferably about 0.0085 inches and most preferably 0.0105 inches. Details of the hooks are shown and described in U.S. Patent Application Publication No. 2007/0112373, filed May 9, 2006.
Alternatively, the hooks can be those shown and described in U.S. Patent Application Publication Nos.
2005/0101982 and 2005/0131451.
[0024] FIG. 2A shows another embodiment of a filter 20. Filter 20 is similar to filter 10 in that it contains three frame members 22 connected together by filaments 26, which in one embodiment are made of suture material, and in other embodiments are made of materials discussed above in connection with possible materials for the frame members.
The filaments 26 of filter 20 do not have a free end extending beyond the most distal frame member. Thus, while in some embodiments, the filaments may include a free end with a hook as described above, in other embodiments, a hook or hooks may be attached along the circumference of one or more =

frame members or may be attached to one or more filaments along their length.
Other embodiments include hooks on both a free end of the filament(s) and the frame member and/or along the length of the filament(s). The frame members 22 are shown in this embodiment in a configuration in which the size of the frame members 22 increase in diameter from a proximal end to a distal end along a longitudinal axis. The frame members 22, however, in filter 20 are unique in that the frame member 22 are adjustable.
[0025]
Specifically, frame members 22 include a first section 23 and a second section 24, the first section 23 having a portion disposed inside and slidable within the second section 24.
Thus, the size and shape of the frame members 22 may be adjusted by moving the first section 23 with respect to the second section 24. A limit member to prevent separation may be included on either or both the first section 23 and the second section 24. In one embodiment, shown in FIG. 2B, a limit member is in the form of a ring 28 coupled, connected to or molded onto the first section 23 of the frame member 22 about the portions that are disposed within the second section 24. In this embodiment, the second section 24 of the frame member 22 contains a shoulder 27 positioned in a passage 21 of the second section 24 adjacent both openings 29 through which portions of the first section 23 are positioned. The shoulders 27 are configured to prevent passage of the rings 28 out of the openings 29, thereby preventing separation of the first section 23 from the second section 24. The rings 28 may be positioned anywhere along the length of the first section 23 and may be sized to provide a friction fit with the passage 21 of second section 24 in order to prevent the first section 23 from movement with respect to second section in the absence of a clinically embodiment, the support structure 52 is a ring stent with anchors as described in U.S. Patent Application Publication No. 2003/0158595.
In one embodiment, the support structure 52 includes a cylindrical shape with a generally uniform distribution of struts 54. The struts 54 together form repeating diamond shapes around the circumference of the structure 52 with a proximal end 56 and a distal end 58.
The support structure may include hooks, which can be configured as discussed above and made of materials such as those discussed as possibilities for the frame members of FIG. 1, on the proximal end 56 and/or distal end 58. In addition, markers 55 may optionally be included on one or both of the proximal and distal ends 56, 58, such as the marker elements described in U.S.
Patent =

Application Publication No. 2004/0015228. The markers 55 preferably include a radiopaque material, such as, for example, tantalum, platinum, gold, iridium or a combination thereof. The markers 55 can be attached to the support structure using methods known to one skilled in the art (e.g., laser welding) and can be arranged in a uniform pattern (e.g., every other strut end, every third strut end, etc.) or a non-uniform pattern. In one embodiment, only a single marker 55 is attached to the proximal end 56 of the support structure 52.
[0034] In one embodiment, the filter 50 includes a covering material 60, such as a graft member, positioned on an inner surface of the support structure 52, an outer surface of the support structure 52, or both. The covering material 60 may include a biocompatible material, such as, for example, expanded polytetrafluoroethylene (ePTFE), polyester, polyurethane, fluoropolymers, such as perfouorelastomers and the like, polytetrafluoroethylene, silicones, urethanes, and combinations thereof, but in a preferred embodiment the covering material 60 includes ePTFE. In one embodiment, the covering material 60 includes an inner ePTFE graft 62 and an outer ePTFE graft 64 that are fused together through openings between struts 54 to at least partially encapsulate the support structure 52. In the embodiment shown in FIG. 5A, the proximal end surfaces of the support structure 52 are left uncovered by the covering material 60, in order, for example, to provide a platform for markers, hooks or both, and/or to provide an attachment point for one or more filaments 62.
[0035] The filament or filaments 62 are attached to the support structure 52, spanning an open region at the proximal end 56 of the support structure 52, to provide a mesh-like surface 64 configured to prevent the passage of blood clots or other debris entering through the open distal end 58 of the support structure 52. In one embodiment, windings of a single the pressure drop is less than 0.2 inch of Hg (as simulated in a 28 mm internal pipe diameter with fluid that simulates blood flow).
[0038] Delivery of various embodiments of the filter described herein can be by any suitable techniques. For example, the filter can be actively delivered via a spring force provided in a delivery catheter. A coil spring can be coupled to a pusher member disposed in the lumen of the delivery catheter. The coil spring is compressed prior to delivery. Once actuated, the spring , provides an abrupt kinetic force to the filter to eject the filter out of the delivery catheter.
Alternatively, other motive force such as a pressurized liquid can be used to eject (via an intermediate member such as a pusher in the lumen of the delivery catheter) the filter out of the delivery catheter. Additionally, a balloon can also be used to ensure full radial expansion of each filter.
[0039] Each of the embodiments described herein may also include a retrieval member to facilitate retrieval of the filter from the blood vessel in which it is placed. The retrieval member may be configured as a hook, loop, rod, shaft, etc., which cooperates with a removal device to permit removal of the filter from the blood vessel. One example of a retrieval member is disclosed in USPN 6,156,055. The retrieval member may be placed on the most proximal frame members (FIGS. 1-2), at the proximal end 34 of the elongated member 32 (FIG.
3), or along a surface of the frame member 42 (FIG. 4). Alternatively, the retrieval member may be positioned along the length of a filament in any of the embodiments described herein, or on a more distal section of the filter (e.g., frame member 13 of FIG. 1, along the length of the elongated member 32 of FIG. 3, etc.).
[0040] Each of the embodiments described herein can be utilized for a blood vessel of at least 28 millimeters. Moreover, each of the embodiments described herein can be loaded into a delivery catheter having an inside diameter of less than about 10French. The length of each embodiment, when deployed, can be about 50 millimeters or less.
[0041] Where the filter is to be utilized with bio-active agents to control the formation of emboli, bio-active agents can be coated to a portion or the entirety of the filter for controlled release of the agents once the filter is implanted. The bio-active agents can include, but are not limited to, vasodilator, anti-coagulants, such as, for example, warfarin and heparin. Other bio-active agents can also include, but are not limited to agents such as, for example, anti-proliferative/antimitotic agents including natural products such as vinca alkaloids (i.e.
vinblastine, vincristine, and vinorelbine), paclitaxel, epidipodophyllotoxins (i.e. etoposide, teniposide), antibiotics (dactinomycin (actinomycin D) daunorubicin, doxorubicin above indicate certain events occurring in certain order, those of ordinary skill in the art will recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain of the steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above.

Claims (16)

10What is claimed is:

1. An implantable medical device, comprising:
a continuous generally circular member defining a frame having an open interior portion; and a plurality of filaments attached to the frame, each filament having a first end connected to the frame at a first point and a second opposite end connected to the frame at a second point different from the first point, the filaments together defining a generally planar mesh-like surface spanning the interior portion of the frame.

2. The implantable medical device according to claim 1, further comprising blood vessel engaging hooks positioned on a surface of the frame.

3. The implantable medical device according to claim 2, wherein at least one of the frame and hooks comprises a bio-resorbable material.

4. The implantable medical device according to claim 1, wherein the frame comprises Nitinol and the filament is selected from a group consisting essentially of suture material, polymer, Nitinol, and combinations thereof.

5. The implantable medical device according to claim 1, further comprising a retrieval member attached to at least one of the frame and the filament.

6. The implantable medical device according to claim 1, wherein connection points of adjacent filaments on the frame are spaced approximately equidistant.

7. The implantable medical device according to claim 1, wherein the frame comprises a first section that has at least one portion disposed inside a second section in a first configuration of the device, and wherein the at least one portion is disposed outside the second section in a second configuration of the device.

8. The implantable medical device according to claim 1, wherein the frame comprises a single continuous member defining a generally circular outer perimeter.

9. An implantable medical device, comprising:
a support structure having an open proximal end; and one or more filaments attached to the support structure to define a generally planar mesh-like surface spanning the open proximal end.

10. The implantable medical device according to claim 9, the support structure including one or more blood vessel engaging hooks.

11. The implantable medical device according to claim 10, wherein at least one of the support structure and hooks comprises a bio-resorbable material.

12. The implantable medical device according to claim 9, wherein the support structure comprises Nitinol and the filament is selected from a group consisting essentially of suture material, polymer, Nitinol, and combinations thereof.

13. The implantable medical device according to claim 9, further comprising a retrieval member attached to at least one of the support structure and the one or more filaments.

14. The implantable medical device according to claim 9, further comprising a covering material disposed on at least one of the surfaces of the support structure.

15. The implantable medical device according to claim 14, wherein the covering material includes a first graft member positioned on an inner surface of the support structure and a second graft member positioned on an outer surface of the support structure.

16. The implantable medical device according to claim 9, further comprising one or more markers attached to the support structure.