US20070032816A1 - Removable Filter Head - Google Patents

Abstract

A filter for use within the lumen of a blood vessel that includes a plurality of interconnected intraluminal filter elements adapted to flexibly convert between a filter configuration and an open configuration. The filter further includes a removable filter head having a retainer and a stopper movable between a first position and a second position. The retainer and the stopper cooperate at the first position to secure the plurality of interconnected intraluminal filter elements into the filter configuration and the movement of the stopper to the second position releases the plurality of interconnected intraluminal filter elements to the open configuration

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This patent claims benefit under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 60/668,036 filed Apr. 4, 2005, the disclosure of which is hereby expressly incorporated herein by reference.
TECHNICAL FIELD
• This patent generally relates to filters for use in the treatment of vascular diseases, and more specifically to filters that include a removable filter head adapted to convert, in vivo, the filter from a filter configuration to an open, stent-like configuration.
BACKGROUND
• Convertible filters for treating vascular disease are known from the present inventor's own U.S. Pat. Nos. 6,267,776 and 6,517,559, the disclosures of which are hereby expressly incorporated herein by reference. These patents disclose numerous embodiments of convertible filters and particularly convertible filters suitable for treatment of vascular disease such as atherosclerotic and embolismic disease.
• Generally, convertible filters include a filter structure having a plurality of filter legs arranged to form a single or double cone filter basket within the vessel lumen to trap blood borne clots or plaque with the vessel. A release member releasable secures the legs or filtering elements of the filter structure such that the filter may have two distinct configurations: filter or open/stent-like. The conversion is affected by release of the release member from the filter legs allowing the spring action of the filter legs themselves or of an externally applied opening force, such the force of a spring coupled to the filter legs, to open the filter legs from the filter configuration to the stent-like configuration. The release member may be a biodegradable material that deteriorates over time to release the filter legs to move to the stent-like configuration.
• In another convertible filter, the release member is a mechanical retainer that includes a hook or similar grasping structure to allow the release member to be physically separated from the filter structure. Removal of the release member involves engaging the grasping structure with a snare and forcing the separation of the release member from the filter structure. The filter structure, which is typically attached to the wall by endothelial tissue, resists the applied force. The release member needs to be releasable from the filter legs with a minimum of force so that the reaction force exerted by the filter legs on the vessel wall does cause detrimental damage to the integrity of the wall. A well-designed release member will facilitate release of the member from the filter legs without transferring significant forces through the filter structure into the vessel wall.
• Upon separation of the release member from the filter legs, the filter structure opens to assume the stent-like configuration along the wall of the blood vessel.
BRIEF DESCRIPTION OF THE DRAWINGS
• For a more complete understanding of the invention, reference should be made to the following detailed description and accompanying drawings wherein:
• FIG. 1 illustrates a side view of an exemplary convertible filter assembly constructed in accordance with the teachings of the present invention;
• FIG. 2 illustrates the convertible filter assembly ofFIG. 1 aligned with a grasping device;
• FIG. 3 illustrates an enlarged view of a removable filter head portion of the convertible filter assembly cooperating with the grasping device in a retracted state;
• FIG. 4 illustrates an enlarged cross-sectional view of the removable filter head and grasping device ofFIG. 3.
• FIG. 5 illustrates a cross-sectional view of the removable filter head taken along the line5-5;
• FIG. 6 illustrates the enlarged cross-sectional view of the removable filter head and grasping device ofFIG. 4 shown in an unsecured position;
• FIG. 7 illustrates the enlarged cross-sectional view of the removable filter head and grasping device ofFIG. 6 after the release of the unsecured filter elements;
• FIG. 7aillustrates the enlarged cross-sectional view of an alternative construction of the removable filter head and grasping device ofFIG. 6 after the release of the unsecured filter elements; and
• FIG. 8 illustrates a perspective view of the convertible filter assembly after separation of the removable filter head.
DETAILED DESCRIPTION
• The removable filter head including a release mechanism constructed in accordance with the teachings of the present invention provides a safe system for converting, in vivo, a convertible filter, such as a vena cava filter, from a closed, filter configuration to an open, stent-like configuration.
• The removable filter head incorporates the release mechanism to releasably secure a plurality of interconnected intraluminal filter elements (filter elements) in a single or double cone filter structure or filter basket. The release mechanism includes a retainer adapted to receive the plurality of filter elements and a stopper movable, relative to the removable filter head and the retainer, between a secured position and an unsecured position. In operation, the filter elements are positioned within the retainer and held in position by, for example, the friction between the retainer, the filter elements and the stopper, when the stopper is in the secured position.
• Movement of the stopper, relative to the removable filter head and the retainer, from the secured position adjacent to the retainer to the unsecured position, releases the filter elements while maintaining the position of the removable filter head relative to the filter elements and the wall of the blood vessel. Subsequently, the released filter elements can convert or expand from the filter configuration to the stent-like configuration when the removable filter head is physically separated from the filter elements.
• FIGS. 1-3 generally illustrate aconvertible filter assembly10 deployed in a filter configuration within the lumen of ablood vessel12. Theconvertible filter assembly10 includes a plurality of intraluminal filter elements (filter elements)14 secured in the filter configuration by aremovable filter head16, as shown inFIG. 1. The term “filter configuration” as used herein refers to theconvertible filter assembly10 when positioned within theblood vessel12 for the treatment of vascular diseases. Similarly, the terms “open configuration” or “stent-like configuration” refer to theconvertible filter assembly10 with theremovable filter head16 separated from thefilter elements14, and theunrestrained filter elements14 extended along awall18 of theblood vessel12.
• Thefilter elements14 in this exemplary embodiment are arranged in a single cone configuration and aligned within theblood vessel12 in the direction of the blood flow indicated by the arrow A to trap matter carried within the blood flow, for example, dislodged blood clots or plaque. Thefilter elements14 each include afilter leg20 flexibly attached to anorientation member22 at aflexure point24. In operation, deployment of theconvertible filter assembly10 within theblood vessel16 allows theorientation members22 to engage thewall18 of theblood vessel12 and align the entireconvertible filter assembly10 with the blood flow. However, it is noted that the particular configuration of the convertible filter, single cone, dual cone, basket, stabilizing members or no stabilizing members, etc., is not critical, and the herein described removable filter head is adaptable to virtually any such structure.
• Thefilter legs20 include aninferior end26 and asuperior end28 aligned along thewall18 of theblood vessel12 by theorientation member22. In particular, theinferior end26 is an unsecured portion of thefilter leg20 positioned upstream from thesuperior end28. Thesuperior end28 is, in turn, bundled and secured together by theremovable filter head16 to form a filter basket generally indicated by thereference numeral30. As used herein to assist the reader, the terms superior and inferior indicate the orientation of theconvertible filter assembly10 within theblood vessel12 and relative to the direction of the blood flow (indicated by the arrow A). For example, the term inferior indicates a downstream position and the term superior indicates an upstream position relative to the direction of blood flow within theblood vessel12.
• Theconvertible filter assembly10 including theremovable filter head16, thefilter legs20 and theorientation members22 may be manufactured from a radiopaque and non-ferromagnetic metal that has been certified for use in medical devices by the International Standards Organization (ISO). Thefilter legs20 and theorientation members22 may be manufactured from metallic wires having, for example, a round, flat or any suitable cross-sectional shape. Theconvertible filter assembly10 may be further drug-coated.
• The wires may be a high cobalt, low ferrous alloy, such as the alloys sold under the registered trademark ELGILOY® which is also referred to as PHYNOX. The composition of these alloys may, by weight percent, be:cobalt 42%, chromium 21.5%,nickel 18%, iron 8.85%, molybdenum 7.5%, manganese 2% with the balance made up of carbon and beryllium having a maximum of 0.15% carbon and 0.001% beryllium. The wires may also be composed of 316L stainless steel or other alloys of nickel and titanium known to be shape-memory metals which are sold and manufactured under the registered trademark NITINOL® or an alloy of tantalum (Ta).Convertible filter assemblies10 constructed from these metals will be non-thrombogenic and preferably withstand twelve million respiratory cycles without mechanical failure.
• FIGS. 2 and 3 generally illustrate theconvertible filter assembly10 deployed within theblood vessel12 and aligned with asnare catheter32. In particular,FIGS. 2 and 3 illustrate the alignment and capture of theremovable filter head16 by thesnare catheter32. Thesnare catheter32, or any other suitable gripping device, can be inserted into the lumen of the blood vessel by any known method of insertion and deployment, and maneuvered through the patient's circulatory system to a position adjacent to theremovable filter head16 and thesuperior end28 of thefilter legs20. Thesnare catheter32 may include asheath34 and asnare36 such as, for example, a gooseneck snare or a hook, slideable relative to thesheath34. Similarly, theremovable filter head16 may include acatch38 or hook adapted to be engaged by thesnare34.
• FIG. 3 illustrates an enlarged view theremovable filter head16 deployed within theblood vessel12 and engaged by thesnare catheter32. In particular,FIG. 3 shows thesnare catheter32 maneuvered, via a patient's circulatory or cardiovascular system, to a position adjacent to theremovable filer head16. From this position, thesnare36 can loop around or otherwise grasp thecatch38 to slideably secure thesnare catheter32 andsheath34 to theremovable filter head16. By increasing the tension in the direction indicated by the arrow T, thesnare36 can be retracted into thesheath34 while simultaneously sliding thesheath34 towards theremovable filter head16. It will be understood that the applied tension T will be sufficient to withdraw thesnare36 into thesheath24, but not great enough to shift or disturb the overall position of theconvertible filter assembly10 relative to thewall18 of theblood vessel wall12.
• FIG. 4 illustrates an enlarged cross-sectional view of thesnare catheter32 in an abutting relationship withremovable filter head16. Specifically, thesnare catheter32 includes atip40, defined as the terminal end of thesheath34, in an abutting relationship with theremovable filter head16. As shown, thetip40 is firmly seated against theremovable filter head16 and thesnare36 and catch38 are retracted into thehollow interior42.
• Theremovable filter head16 is a roughlycylindrical body44 that includes an open first end46 and a second end48 that includes aretainer50 formed integrally therein. The open first end46 accepts anend cap52 sized to close and/or seal the roughlycylindrical body44. Theend cap52 includes alip56 which can be seated against atop edge60 of thecylindrical body44, and acylindrical wall58 sized to cooperate with the interior surface of thecylindrical body44 such that thelip56 and atop edge60 of thecylindrical body44 are in an abutting relationship. Thecylindrical wall58 and thecylindrical body44 may be held together in a press-fit or friction arrangement, may include male and female threads and be rotatably joined and may be glued, welded or otherwise secured together in any desired manner. The end cap may further include an external,flat surface54 arranged to bear against and/or bias thetip40 of thesheath34 when thesnare36 and catch38 are retracted into thehollow interior42. Theflat surface54 provides a firm contact between the two components, theremovable filter head16 and thesnare catheter32, and allows the transmission of forces therebetween.
• Theend cap52 further includes anorifice62 sized to slideably accept arod portion64 connected to thecatch38. Therod portion64 extends through theorifice62 into an interior66 of thecylindrical body44 to engage astopper70 having a contiguously formedshaft68. Thestopper70, as shown in this exemplary embodiment, is a roughly cylindrical component sized to releasably engage theretainer50 formed at the second end48 of thecylindrical body44. In operation, thestopper70 is movable within theinterior66 of thecylindrical body44 between a secured position adjacent to theretainer50, and an unsecured position adjacent to theend cap54.
• Thestopper70 includes varying diameter portions that define aflange72 and plug74. Theflange74 and plug74, of this present embodiment, are integral elements which are aligned coaxially with theshaft68 and therod portion64. Physically, theflange72 is a radially extending disc that compliments the interior66 of thecylindrical body44 and theplug74 has a reduced diameter, relative to theflange72, sized to cooperate with theretainer50 when thestopper70 is in the secured position. Theshaft68, as shown, may includes ablind bore76 sized to securely accept therod portion64 in, for example, a threaded or press fit arrangement. Theremovable filter head16 may further include apush nut78 positioned adjacent to thecylindrical wall58 of theend cap52 to hold thestopper70, via theshaft68 andflange72, in secure contact with theretainer50.
• A force applied through thecatch38 androd portion62 in the direction indicated by the arrow T allows theshaft68 to elastically deform thepush nut78 and move thestopper70 to the unsecured position adjacent48 to thecylindrical wall58 of theend cap52. Thecylindrical wall58 and pushnut78 cooperate with theflange72 to limit the overall movement of thestopper70 to the unsecured position adjacent to theend cap52. Theshaft68 further includes a reduceddiameter portion80 adjacent to theflange72 and arranged to cooperate with thepush nut78 to, upon movement to the unsecured position at the open first end46, prevent thestopper70 and plug from reengaging theretainer50.
• Theplug74 and theretainer50 cooperate to compressively engage and retain the superior ends28 of thefilter legs20 when thestopper70 is in the secured position. Thesuperior end28 of thefilter legs20 may be aligned within a plurality of grooves82 (seeFIG. 5) formed within theretainer50 at the second end48 of thecylindrical body44. The alignedfilter legs20 may, in turn, be held in position by inserting theplug74 into theretainer50 and creating an interference fit therebetween. Moreover, theflange72 may be sized and arranged to compressively engage the aligned superior ends of thefilter legs20 against theretainer50. In this way, the superior ends28 of thefilter legs20 are aligned and secured within thecylindrical body44 of theremovable filter head16 to thereby create thefilter basket30.
• FIG. 6 illustrates an enlarged cross-sectional view of theremovable filter head16 in an abutting relationship with thetip40 of thesnare catheter32. In particular, thecatch38 and thesnare36 are withdrawn into thesheath34 such that thetip40 is firmly seated against theflat surface54. Moreover, the application of tension through thesnare26 and thecatch38, in the direction indicated by the arrow T, forces thestopper70 to move towards the unsecured position adjacent to theend cap52.
• The movement of thestopper70, in turn, causes theshaft68 to bear against and elastically deform thepush nut78. In particular, the stopper movement elastically deforms the fingers, indicated by thenumerals78aand78b, of thepush nut78. The elasticallydeformed fingers78a,78bride along theshaft68 and engage a reduceddiameter portion80 to prevent thestopper70 from returning to the secured position adjacent to theretainer50. Similarly, theflange72 engages thecylindrical wall58 and prevents additional movement or over-travel in the direction of theend cap52. In this way, thestopper70 is locked into the unsecured position away from theretainer50 and between theend cap52 and theretainer50. The reduceddiameter portion80 may further act as a detent such that as thestopper70 arrives at the unsecured position, it is engaged by the reduced diameter portion to retain it in the unsecured position. The action of the fingers sliding from theshaft68 to the reduced diameter portion may also provide a haptic snap or click indication through the catheter, allowing the medical professional to know that thestopper70 is fully retracted to the unsecured position.
• The tension applied to retract thestopper70 and elastically deform thepush nut78, can cause the entireconvertible filter assembly10 to move in order to react forces against theblood vessel wall18. In order to limit force transfer to the vessel wall, the tension applied through thesnare36 is counteracted and balanced by an equal and opposite force applied to theflat surface54 through thesheath34. In this way, while thecatch38 and the attachedstopper70 are forced to disengage from theretainer50, the counterforce applied through thesheath34 maintains the position of theremovable filter head16 and attachedfilter elements14, relative to theblood vessel wall18.
• As shown inFIG. 6, upon disengagement of theplug74 from theretainer50, thestopper70 remains secured adjacent to theend cap52 by the cooperation of the reduceddiameter portion80 and thefingers78a,78bof thepush nut78. The superior ends28 of thefilter legs20 will typically remain aligned within thegrooves82 of theretainer50, but will be unfettered and ready for release. This arrangement allowsconvertible filter assembly10 to be transitioned from the filter configuration to the open or stent-like configuration by releasing the superior ends28 of thefilter legs20 from theretainer50.
• As outlined above, the process of transitioning theconvertible filter assembly10 begins with maneuvering and aligning thesnare catheter32 and thesnare36 with theremovable filter head16 and thecatch38. The alignedsnare36 engages thecatch38, and thesheath34 is positioned in contact with theflat surface54 of theend cap52. In this way, thetip40 of thesnare catheter32 abuts the removable filter head16 (through contact with the end cap52) and thesheath34 encloses both thesnare36 and thecatch38.
• Application of tension in the direction of the arrow T to the free end of thesnare36, e.g., the end of thesnare36 which is outside of the patient's body, pulls thecatch38 deeper into thesheath34 and forces the attachedstopper70 to disengage from theretainer50. It will be understood that unless the tension is greater than the force generated by thefingers78a,78bof thepush nut78 and the friction between theplug74 and theretainer50, thestopper70 cannot be disengaged. Simultaneously, a counterforce can be applied to theremovable filter head16 through thesheath34 in order to balance and counteract the effects of the tension applied through thesnare36. In other words, as thesnare36 is pulled to release theplug74 from theretainer50, thesheath34 is pushed to engage theremovable filter head16 through theflat surface54 of theend cap52 and prevent movement relative to theblood vessel wall18.
• By overcoming the friction between theplug74 and theretainer50, theshaft68 elastically deforms thefingers78a,78bof thepush nut78 and allows thestopper70 to move away from theretainer70 and to the unsecured position adjacent to theend cap52. Thefingers78a,78b, in turn, engage the reduceddiameter portion80 and lock or otherwise prevent thestopper70 from reengaging theretainer50. The movement of thestopper70 is further limited, by the interference between theflange72 and thecylindrical wall58 of theend cap52. This release mechanism within theremovable filter head16 allows thestopper70 to be disengaged from theretainer50 and prevents unwanted reengagement of the components.
• FIG. 7 illustrates theremovable filter head16 after thestopper70 and plug74 have been disengaged from theretainer50. The unrestrained superior ends28 of thefilter legs20 have been released from thegrooves82, and have flexed or expanded to the open or stent-like configuration. Generally, in order to disengage theremovable filter head16 and release the superior ends28 of thefilter legs20, the entireremovable filter head16 is pulled, via thesnare catheter32, away from thefilter elements14 lodged or encapsulated in thewall18 of theblood vessel12. In this way, theremovable filter head16 and thesnare catheter32 are separated from thefilter elements14 for extraction through the patient's circulatory system. Thefilter elements14 remain secured to thewall18 of theblood vessel12 in the open or stent-like configuration.
• FIG. 7aillustrates an alternative construction of theremovable filter head16 after the stopper and plug74 have been disengaged from theretainer50. Like reference numerals designate like elements. Theretainer50 is formed with a smooth bore that receives the superior ends28 of the filter legs. The stopper and plug74 are formed withgrooves82′ that engage and align the filter legs with the stopper and plug74 in the secured position, and, as shown inFIG. 7a, release the filter legs when in an unsecured position. Alternative arrangements whereingrooves82/82′ are formed in one or both of theretainer50 or plug74 may be used.
• FIG. 8 illustrates the releasedintraluminal filter elements14 expanded and extended along thewall18 of theblood vessel12. In this open or stent-like configuration, thefilter basket30 is open and allows blood to flow freely through theblood vessel12.
• Although certain embodiments have been described in accordance with the teachings of the present disclosure, the scope and coverage of this patent is not limited thereto. For instance, while theremovable filter14 has been illustrated and describes as having a cylindrical body, it will be understood that any desired shape or configuration may be employed. Further, while a specific embodiment of theintraluminal filter elements14 has been described herein, many other single or double cone arrangements may be employed. This patent is intended to cover all embodiments of the teachings of the disclosure that fairly fall within the scope of the permissible equivalents.

Claims (15)

1. A filter for use within the lumen of a blood vessel that includes a plurality of interconnected intraluminal filter elements adapted to flexibly convert between a filter configuration and an open configuration, the filter comprising:

a removable filter head including,

a retainer; and

a stopper movable between a first position and a second position;

wherein the retainer and the stopper cooperate at the first position to secure the plurality of interconnected intraluminal filter elements into the filter configuration and wherein the movement of the stopper to the second position releases the plurality of interconnected intraluminal filter elements to the open configuration.

2. The filter ofclaim 1 further comprising a catch fixedly attached to the stopper and adapted o mechanically release the stopper from the retainer in response a releasing force.

3. The filter ofclaim 2, wherein the releasing force is provided by a snare catheter positioned adjacent to the catch and the removable filter head.

4. The filter ofclaim 2, wherein the catch is a hook adapted to cooperate with a snare portion of the snare catheter to mechanically release the stopper from the retainer.

5. The filter ofclaim 1, wherein the removable filter head includes a push nut arranged to limit the travel of the stopper relative to the retainer.

6. The filter ofclaim 5, wherein the push nut includes a plurality of elastically deformable fingers adapted to secure the stopper in the second position.

7. The filter ofclaim 1, wherein the retainer includes a plurality of grooves adapted to receive the plurality of interconnected intraluminal filter elements

8. A removable filter head adapted to secure a plurality of interconnected intraluminal filter elements in a filter configuration, the removable filter head comprising:

a retainer sized to accept the plurality of interconnected intraluminal filter elements; and

a stopper movable between a first position and a second position relative to the retainer, wherein the stopper is sized to engage the plurality of interconnected intraluminal filter elements and the retainer, and wherein the movement of the stopper from the first position to the second position releases the plurality of interconnected intraluminal filter elements.

9. The removable filter head ofclaim 8, further comprising a catch fixedly attached to the stopper and arranged to move the stopper from the first position to the second position in response to a releasing force.

10. The removable filter head ofclaim 9, further comprising a flat surface arranged to bias the releasing force and prevent movement of the retainer relative to the plurality of interconnected intraluminal filter elements.

11. The removable filter head ofclaim 10, wherein the releasing force is transmitted by a catheter having a snare, and wherein the catheter is arranged to abut the flat surface and the snare is arranged to engage the catch.

12. The removable filter head ofclaim 9, wherein the catch is a hook fixedly attached the stopper and sized to cooperate with a snare catheter to move the stopper to the second position.

13. The removable filter head ofclaim 8, wherein the retainer body includes a push nut arranged to limit the movement of the stopper.

14. The removable filter head ofclaim 8, wherein the stopper includes a flange sized to compressively engage the plurality of interconnected intraluminal filter elements.

15. A method of converting a filter including a plurality of interconnected intraluminal filter elements positioned within the lumen of a blood vessel to an open configuration, the method comprising:

inserting a snare catheter having a first end into the lumen of the blood vessel;

positioning the snare catheter adjacent to a removable filter head having a retainer and a release mechanism, wherein the release mechanism is adapted to releasably secure the plurality of interconnected intraluminal filter elements;

engaging the release mechanism with snare catheter;

shifting the release mechanism relative to the removable filter head and the retainer to thereby release the plurality of interconnected intraluminal filter elements.

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