US20090192543A1 - Retrievable ivc filter - Google Patents

Abstract

Retrievable vena cava filters for filtering blood clots within a vessel are disclosed. A retrievable vena cava filter in accordance with an exemplary embodiment of the present invention may include a plurality of elongated filter legs each having a hook portion configured to engage the vessel wall, and an expandable member releasably connected to the filter. In certain embodiments, the expandable member may comprise a bendable member and several tubular members, or a coiled wire.

Description

RELATED APPLICATIONS
• This application is a continuation application of U.S. application Ser. No. 10/361,983 filed Feb. 11, 2003.
FIELD OF THE INVENTION
• The present invention relates to devices for filtering blood clots within a vessel. More specifically, the present invention pertains to retrievable intravascular filter devices implantable within the vena cava.
BACKGROUND OF THE INVENTION
• Vena cava filters are utilized in conjunction with anti-coagulants and thrombolytic agents to prevent pulmonary embolism and other vascular diseases from occurring within the body. These devices are generally implanted within a vessel such as the inferior vena cava, and function by capturing blood clots (emboli) contained in the blood stream before they can reach the lungs and cause permanent damage to the patient.
• To trap emboli, many conventional vena cava filters employ several independent filter legs that can be expanded in the vessel to form a conical-shaped filtering surface on which emboli can be collected. To enable ligation of the filter within the body, a hook, barb or other piercing means on the each filter leg can be used to anchor the filter along the cava wall. After a period of time within the body, tissue on the vessel wall begins to form about the ends of the filter legs, making removal of the device more difficult. In some circumstances, it may be desirable to remove the filter from the patient's body.
SUMMARY OF THE INVENTION
• The present invention relates to retrievable intravascular filter devices and methods for filtering blood clots within a vessel. In an exemplary embodiment of the present invention, a retrievable vena cava filter may comprise a plurality of elongated filter legs each having a hook portion configured to releasably secure the filter to the wall of a vessel, and an expandable member releasably connected to the filter. The filter legs may be biased to expand from a substantially straight configuration to an outswept, conical-shaped configuration when deployed in the vessel. The expandable member may include a plurality of anchoring members configured to pierce and secure the expandable member to the vessel wall. In some embodiments, the expandable member may comprise a bendable member interconnected to several tubular members. In other embodiments, the expandable member may comprise a coiled wire. In use, the expandable member may be utilized to compress the filter legs against the vessel wall.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of an intravascular filter device in accordance with an exemplary embodiment of the present invention;
• FIG. 2 is a top view of the intravascular filter device ofFIG. 1, showing the filter engaged within a vessel;
• FIG. 3 is a partial perspective view of one of the elongated filter legs illustrated inFIG. 1, showing the filter leg engaged along the wall of the vessel;
• FIG. 4 is a perspective view of an intravascular filter device in accordance with another exemplary embodiment of the present invention, wherein the filter device includes an expandable member;
• FIG. 5 is a perspective view of the distal portion of one of the filter legs illustrated inFIG. 4;
• FIG. 6 is a top view of the intravascular filter device ofFIG. 4, showing the filter device engaged within a vessel;
• FIG. 7 is a perspective view of an intravascular filter device in accordance with another exemplary embodiment of the present invention, wherein the expandable member comprises a coiled wire;
• FIG. 8 is a perspective view of the distal portion of one of the filter legs illustrated inFIG. 7;
• FIG. 9 is a partial cross-sectional view of an intravascular filter device temporarily placed in a vessel;
• FIG. 10 is another partial cross-sectional view showing the intravascular filter device withdrawn such that the proximal portion of each filter leg is disengaged from the vessel wall;
• FIG. 11 is another partial cross-sectional view showing the intravascular filter device further withdrawn such that the distal portion of each filter leg is decoupled from the tubular members; and
• FIG. 12 is another partial cross-sectional view showing the intravascular filter device collapsed at least in part within a retrieval sheath.
DETAILED DESCRIPTION OF THE INVENTION
• The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Although examples of construction, dimensions, and materials are illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.
• FIG. 1 is a perspective view of anintravascular filter device10 in accordance with an exemplary embodiment of the present invention.Intravascular filter10 comprises anapical head12, and a plurality ofelongated filter legs14 each having adistal section16 and aproximal section18. Each of thefilter legs14 may be configured identically with respect to each other, and may be symmetrically spaced about a central longitudinal axis L in a generally conical-shaped configuration when expanded. Theelongated legs14 may be collectively arranged about the longitudinal axis L such that theproximal section18 of eachfilter leg14 converges at theapical head12 to form an apex. Thefilter legs14 may be biased to expand from a substantially straight position when radially constrained within a delivery device to an outswept position when deployed in a blood vessel.
• Thefilter legs14 may be formed from a metal such as platinum, gold, tantalum, tungsten, titanium, or a metal alloy such as stainless steel (e.g. type 304V), Beta III Titanium, cobalt-chrome alloy, Elgiloy, L605, MP35N, Ta-10W, 17-4PH, or Aeromet 100. Thefilter legs14 may also include an anti-thrombogenic coating such as herapin (or its derivatives), urokinase, or PPack (dextrophenylalanine proline arginine chloromethylketone) to prevent insertion site thrombosis.
• In certain embodiments, thefilter legs14 may be formed from a shape-memory material such as nickel-titanium alloy (Nitinol). A slight outward bend can be imparted to eachfilter leg14 by heating the alloy beyond its final austenitic temperature, and then bending eachfilter leg14 to a pre-defined shape. Thefilter legs14 can be configured to revert to their pre-defined (i.e. bent) shape at or near body temperature (37° C.), allowing eachindividual leg14 to maintain a straight position until deployed in the vessel.
• FIG. 2 is a top view of theintravascular filter device10 ofFIG. 1, showing thefilter device10 deployed within a vessel V. As shown inFIG. 2, thefilter legs14 extend outwardly from theapical head12 to anchor thefilter device10 along the inner wall W of the vessel V. Thefilter legs14 can be arranged at equidistant intervals such that thefilter legs14 are symmetrically spaced about the longitudinal axis formed by theapical head12. In the exemplary embodiment illustrated,intravascular filter10 includes sixfilter legs14 arranged at 60° intervals. It is to be understood, however, that any number or arrangement of filter legs can be employed in accordance with the present invention.
• Thedistal section16 of eachfilter leg14 includes ahook portion20 configured to pierce the inner wall of the vessel V and prevent migration of thefilter device10 within the body. In use, eachhook portion20 compresses against the inner wall W of the vessel V as a result of the outwardly directed force exerted by thefilter legs14. The dimensions and material composition of thefilter legs14 can be selected to impart a desired amount of force to thehook portion20.
• FIG. 3 is a perspective view of one of thefilter legs14 illustrated inFIG. 1, showing thefilter leg14 engaged within the wall W of a vesselV. Hook portion20 includes asharp tip22 that pierces the vessel wall W, enabling ligation of the filter within the vessel. In certain embodiments, thehook portion20 may including abend region24 orienting thesharp tip22 at an angle θ relative to the wall W of the vessel. V. In some embodiments, thebend region24 orients thehook portion20 at an angle θ substantially perpendicular to the vessel wall W. In other embodiments, thebend region24 orients thesharp tip22 at an acute or obtuse angle θ relative to the vessel wall W. Each of thebend regions24 can be similarly oriented such that each of thesharp tips22 pierces the vessel wall W at approximately the same angle.
• Intravascular filter device10 may further include a plurality oftubular members28 configured to permanently engage the vessel wall W. Eachtubular member28 includes adistal end30, aproximal end32, and aninner lumen34 therebetween configured to slidably receive one of thefilter legs14. Azigzag section26 on eachfilter leg14 prevents thetubular members28 from retracting proximally toward theproximal section18, and prevents the conical-shaped filtering portion of eachleg14 from contacting the vessel wall W.
• Thetubular members28 may be formed of short segments of hypodermic tubing comprising a metal, metal alloy, or metal-polymer blend. Examples of suitable materials include stainless steel (e.g. type 304V), platinum, tungsten, nickel-titanium alloy, polyethylene terapthalate (PET), polytetraflouroethylene (PTFE), polyurethane (nylon) fluorinated ethylene propylene (FEP), polyurethane, polypropylene (PP), polyvinylchloride (PVC), polyether-ester, polyester, polyamide, elastomeric polyamides, block polyamide/ethers, polyether block amide (PEBA), silicones, polyethylene, polyether-ether ketone (PEEK), polyimide (PI), and polyetherimide (PEI). Theinner lumen34 of eachtubular member28 may also include a lubricious coating such as polytetraflouroethylene (PTFE).
• Eachtubular member28 may include a hook, pin, needle, prong, barb, wedge or other piercing means36 adapted to permanently engage and secure thetubular member28 to the vessel wall W. The piercing means36 may be adapted to bend or flex about ajoint38, allowing the piercing means36 to bend and compress against thetubular member28 when placed in a delivery catheter or sheath. An anti-inflammatory agent such as dexamethasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazine, mesalamine, or any suitable combination or mixture thereof may be applied to eachfilter leg14 andtubular member28 to prevent inflammation caused by the engagement of the device along the vessel wall W.
• FIG. 4 is a perspective view of anintravascular filter device110 in accordance with another exemplary embodiment of the present invention, wherein thefilter110 includes anexpandable member140,Intravascular filter device110 comprises anapical head112, and a plurality ofelongated filter legs114 each having adistal section116, aproximal section118, and azigzag section226. As with the previous embodiment, thefilter legs114 may be symmetrically spaced in a generally conical-shaped configuration, and may be configured identically to each other. Thefilter legs114 may be biased to expand from a substantially straight position when radially constrained within a delivery device to an outswept position when deployed in the blood vessel.
• Theexpandable member140 may comprise a plurality oftubular members128 interconnected by abendable member142 biased to radially expand and compress against the wall of the vessel when deployed. As shown inFIG. 5, eachtubular member128 has adistal end130, aproximal end132, and aninner lumen134 configured to slidably receive one of thefilter legs114. A hook, pin, needle, prong, barb, wedge or other piercing means136 may be used to permanently engage and secure eachtubular member128 to the wall of the vessel. A flexible joint138 connecting the piercing means136 to thetubular member128 allows the piercing means136 to bend and compress against thetubular member128 when loaded into the delivery device.
• FIG. 6 is a top view showing theintravascular filter device110 engaged along the wall W of a vessel V. In an expanded position illustrated inFIG. 6, thefilter legs114 extend outwardly from theapical head112, compressing against the wall W of the vessel V. Thehook portion120 on eachfilter leg114 pierces the vessel wall W, fixing the location of thefilter110 within the vessel V.
• As can be further seen inFIG. 6, theexpandable member140 likewise expands when deployed in the vessel V. In use, theexpandable member140 maintains thefilter legs114 at equidistant intervals (e.g. 60°) to each other, preventing thefilter legs114 from asymmetrically deploying within the vessel V.
• FIG. 7 is a perspective view of anintravascular filter device210 in accordance with another exemplary embodiment of the present invention, wherein theexpandable member240 comprises acoiled wire250.Intravascular filter210 is similar to that depicted in other embodiments described herein, comprising anapical head212, and a plurality ofelongated filter legs214 each having adistal section216, aproximal section218, and azigzag section226.
• Thecoiled wire250 may be formed from a wire having several alternatingstraight sections252 andcoiled sections254. As with other embodiments described herein, thecoiled wire250 may be biased to radially expand and compress against the wall of the vessel when deployed. As shown inFIG. 8, eachcoiled section254 has adistal end256, aproximal end258, and aninner lumen260 configured to slidably receive one of thefilter legs214. A hook, pin, needle, prong, barb, wedge or other piercing means236 may be used to permanently engage and secure theexpandable member240 to the wall of the vessel. A flexible joint238 connecting the piercing means236 to thecoiled section254 allows the piercing means236 to bend and compress against thecoiled section254 when loaded into the delivery device.
• Thecoiled wire250 may be formed from a single piece of wire that can be wound at various locations to form the desired number of coiledsections254. Eachcoiled section254 may be formed by wrapping the wire about a mandrel having an outer diameter slightly larger than the outer diameter of the filter legs. Once thecoiled sections254 have been formed, the wire may then be wrapped around a larger mandrel with the coiledwire sections254 arranged parallel to the longitudinal axis of the mandrel. The wire can then be connected at its ends and heat set, forming thecoiled wire250 depicted inFIG. 7.
• Turning now toFIGS. 9-12, methods of retrieving an IVC filter will now be described with respect to filterdevice110 described above. To prepare thefilter device110 prior to insertion in the body, the user straightens thehook portion120 of eachfilter leg114 such that thesharp tip122 is oriented in a direction substantially parallel to the longitudinal axis of thefilter leg114. With thehook portion120 straightened, the user inserts thedistal section116 of thefilter leg114 into thelumen134 of thetubular member128, and slides thetubular member128 distally along thefilter leg114 until theproximal end130 is located immediately adjacent thezigzag region126. Once loaded, the user bends thedistal section116 of thefilter leg114 to the desired angle (e.g. 90°), and loads thefilter110 into a delivery device such as a catheter or sheath.
• Once loaded, the delivery device is then percutaneously inserted into the body, and advanced to a desired vessel within the body (e.g. the inferior vena cava). Thefilter device110 is then removed from within the delivery device, causing thefilter legs114 andexpandable member140 to deploy and engage the wall W of the vessel V, as shown inFIG. 9. As thefilter110 is deployed, thesharp tip122 onhook portion120 pierces the cava wall W, temporarily fixing thefilter110 within the vessel V. Moreover, the piercing means136 on eachtubular member128 similarly pierces the cava wall W, fixing theexpandable member140 within the vessel V. With thefilter110 deployed and engaged within the vessel V, embolic debris contained within the blood can then be collected and stored on thefilter legs114.
• To remove thefilter device110 from the vessel, aretrieval mechanism144 can be utilized to engage ahook146 on theapical head112 to retract thefilter device110 proximally a short distance, causing thehook portion120 on eachfilter leg114 to straighten and eject from within thetubular member128, as shown inFIG. 10. Further retraction of thefilter device110 proximally causes thefilter legs114 to decouple from theexpandable member140, as shown inFIG. 11. A retrieval device such as thesheath148 depicted inFIG. 12 can then be utilized to radially collapse and remove thefilter device110 from the body.
• Having thus described the several embodiments of the present invention, those of skill in the art will readily appreciate that other embodiments may be made and used which fall within the scope of the claims attached hereto. Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size and arrangement of parts without exceeding the scope of the invention.

Claims (15)

1. (canceled)

2. A retrievable vena cava filter, comprising:

a plurality of elongated filter legs each having a proximal section and a distal section, the distal section of each elongated filter leg including a hook portion configured to releasably secure the vena cava filter to the wall of a blood vessel; and

a plurality of tubular members each including an inner lumen configured to receive a corresponding one of the elongated filter legs.

3. The retrievable vena cava filter of claim16, wherein said plurality of elongated filter legs are configured to expand from a substantially straight position to an outswept position when placed in the blood vessel.

4. The retrievable vena cava filter of claim16, wherein said plurality of elongated filter legs comprise stainless steel.

5. The retrievable vena cava filter of claim16, wherein said plurality of elongated filter legs comprise a shape-memory material.

6. The retrievable vena cava filter of claim19, wherein said shape-memory material is nickel-titanium alloy.

7. The retrievable vena cava filter of claim16, wherein said book portion includes a sharp tip.

8. The retrievable vena cava filter of claim21, wherein said sharp tip is bent at an angle relative to the vessel wall.

9. The retrievable vena cava filter of claim21, wherein said sharp tip is bent at an angle perpendicular to the vessel wall.

10. The retrievable vena cava filter of claim16, further comprising means for interconnecting the tubular members.

11. The retrievable vena cava filter of claim24, wherein said means for interconnecting the tubular members comprises a bendable member biased to expand when placed in the blood vessel.

12. The retrievable vena cava filter of claim16, wherein each of said tubular members includes piercing means for securing the tubular member to the vessel wall.

13. The retrievable vena cava filter of claim16, wherein each of said plurality of elongated filter legs includes a bend region.

14. The retrievable vena cava filter of claim16, further comprising an apical head secured to the distal section of said plurality of elongated filter legs.

15. The retrievable vena cava filter of claim16, wherein each of said plurality of filter legs includes a zigzag section.

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