Patent Application
20110152919
This invention relates generally to intravascular devices and more particularly to filter devices implantable within the vena cava for capturing dislodged clots or debris.
Vena caval filters can be 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, to capture dislodged blood clots (emboli) contained in the blood stream. If a blood clot forms in the deep veins of a lower extremity and dislodges, the blood clot may proceed up the vena cava into the heart and into the pulmonary arteries, where it may block and interrupt blood flow. Mortality is typically high in the event of pulmonary embolism.
Filtering devices that are placed in the vena cava have been available for a number of years. Various vena caval filters have been developed over the years, including the Mobin-Uddin umbrella filter, introduced in 1967 and discontinued in 1986. The Greenfield vena caval filter has been in wide use for a number of years and is known as the standard in vena caval filters.
To trap emboli, many conventional vena caval filters employ several independent filter legs that can be expanded within the vessel to form a substantially conical-shaped filtering profile within which emboli or clots can be collected. To prevent migration of the filter within the vessel, a hook, barb or other piercing or anchoring mechanisms on the filter leg can be used to secure the filter to the wall of the vena cava. For example, the Greenfield filter has multiple legs meeting at a central apex and has attachment hooks on the legs. Deployment of the Greenfield filter often occurs in a tilted fashion, which decreases clot capture ability of the filter. Moreover, the Greenfield filter is placed in the vessel in one direction that funnels clots to the apex of the filter and the center of the vessel. In addition, the attachment hooks on the legs of the Greenfield filter are also uni-directional and positioned for funneling clot to the apex of the filter. Thus, continued use of the Greenfield filter in the vessel may lead to accumulation of clots near the apex of the filter, and may further block and interrupt blood flow near the center of the vessel.
Furthermore, it should be noted that a percentage of patients only need a vena caval filter as protection from a pulmonary embolism for a short period of time. As such, leaving an implantable filter in place for an extended period of time may lead to complications, including inferior vena cava thrombosis, deep venous thrombosis, filter migration, and vena cava perforation. Therefore, in some circumstances, it may be desirable to remove the filter from the patient.
Removal of the filter from the vena cava, however, is met with certain hurdles. For example, some of these filters may not be easily removable from a patient due to fibrous in-growth into the filter. In particular, after deployment of a filter in a patient, proliferating intimal cells can start accumulating around the filter framework in contact with the wall of the vessel. After a length of time, such accumulation or in-growth can prevent removal of the filter without risk of trauma, requiring the filter to remain in the patient.
Another hurdle to removing a filter from the vena cava results from conventional vena caval filters becoming off-centered or tilted with respect to the hub of the filter as well as the longitudinal axis of the vessel within which the filter is situated. Removal of an off-centered or tilted filter can be difficult as the barbs or hooks securing the filter in place can dig further into the vessel walls and act to injure or damage the vessel during removal.
Accordingly, it would be desirable to have an effective vena caval filter that can be eliminated after the underlying condition has passed, while avoiding damaging the tissue of the vessel wall within which the filter is located.
The present invention provides, in one embodiment, a filter device for capturing undesirable materials (e.g., clots). The device includes a self-expanding framework defined by a plurality of legs. The filter device can also include a proximal portion on the expandable framework designed for secured placement of the device against a wall of a vessel. In certain embodiments, the expandable framework includes an attachment mechanism at the proximal portion to enhance secured placement of the device against the wall of the vessel. The framework, in an embodiment, may be designed to permit undesirable materials to flow into the framework from the proximal portion towards the filter portion. The filter device can additionally include a filter portion in linear alignment with the proximal portion and formed by constraining the plurality of legs towards an apex. In some embodiments, the plurality of legs in the filter portion can be designed to capture undesirable materials flowing through the vessel and direct the captured undesirable materials toward the apex. In various embodiments, the filter device can include a securing element at the apex to maintain the plurality of legs in a constrained position, and which upon elimination allows the plurality of legs to expand radially outward, such that a substantially tubular pathway is established through the expandable framework. The securing element can be, for example, one of bio-absorbable, breakable, removable, or any combination thereof.
In another embodiment, the present invention provides a filter device that can include an expandable framework having a substantially tubular proximal portion for secured placement of the device against a wall of a vessel. In certain embodiments, the framework can include an attachment mechanism to enhance secured placement of the device against the wall of the vessel. The filter device can also include an elongated leg extending beyond the proximal portion. The elongated leg, in an embodiment, can include a securing mechanism at an end opposing the framework at which the filter can terminate. The device further includes a pathway extending through the framework. The device can also include a continuous element extending through the framework between the proximal portion and the elongated leg to define a filter. In some embodiments, the filter can act to capture undesirable materials flowing through the vessel from the framework towards the elongated leg. The continuous element, upon elimination, may allow establishment of a substantially tubular pathway through the framework.
In yet another embodiment, the present invention provides a bi-directional filter device that can include an expandable framework for secured placement of the device against a wall of a vessel. The framework, in an embodiment, includes an attachment mechanism to enhance secured placement of the device against the wall of the vessel. The filter device can also include a pathway extending through the expandable framework. Additionally, the filter device can include a continuous element extending within the pathway between a proximal portion and a distal portion of the framework to define opposing filters within the framework, and which upon elimination allows establishment of a substantially tubular pathway through the framework. In certain embodiments, the opposing filters within the framework can include an apex situated between the opposing filters.
The present invention, in another aspect, also features methods for capturing undesirable material. The method, in one embodiment, can include initially providing an expandable framework defined by a plurality of legs constrained towards an apex with a securing element to form a filter portion in linear alignment with the proximal portion. Next, a proximal portion on the expandable framework may be secured against a wall of a vessel. Thereafter, undesirable materials may be allowed to flow into the framework toward the filter portion to permit the undesirable material to be captured thereat. In certain embodiments, the step of allowing includes directing the captured undesirable materials toward the apex. The method can further include eliminating the securing element to allow the plurality of legs to expand radially outward such that a substantially tubular pathway is provided through the expandable framework.
In another embodiment, the method for capturing undesirable material can include initially placing an expandable framework having a substantially tubular proximal portion and an elongated leg extending beyond the proximal portion. Next, a continuous element may be provided through the framework between the proximal portion and the elongated leg so as to form a filter portion therebetween. Thereafter, the substantially tubular proximal portion may be secured against the wall of the vessel to provide a substantially tubular pathway through the framework. Then, undesirable materials may be allowed to flow into the framework toward the filter portion to permit the undesirable material to be captured thereat. The method can further include eliminating the continuous element extending through the framework between the proximal portion and the elongated leg, so as to establish a substantially tubular pathway through the framework.
In yet another embodiment, the method for capturing undesirable material can include initially placing an expandable framework having a proximal portion and a distal portion. Next, a continuous element may be provided through the framework between the proximal portion and the distal portion so as to define opposing filters within the framework. Thereafter, the expandable framework may be secured against a wall of a vessel. Subsequently, undesirable material may be allowed to flow into the framework to permit the undesirable material to be captured by at least one of the opposing filters. The method can further include eliminating the continuous element defining the opposing filters within the framework, so as to establish a substantially tubular pathway through the framework.
As used herein, in addition to the other terms defined in this disclosure, the following terms may have the following meanings:
“Arms” or “legs” means an elongated member or a slender part extending from a proximal end to a distal end.
“Bidirectional” means a filter device that can be used in two opposing directions; i.e., either end can allow a fluid to flow through the filter while capturing undesirable materials. “Uni-directional” or “one-directional” means a filter device that can be used in one direction only; i.e., a fluid can flow through the filter from one end to the other only while capturing undesirable materials.
“Blood clots”, “clots”, “emboli” and “debris” refers to substances found within blood flow that can be filtered using the vascular filter device of the present invention. They can have various profiles (e.g., from substantially stringy to substantially globular) and sizes (e.g., from less than 1 mm to a few centimeters). “Blood clots”, “clots”, “emboli” and “debris” can be used interchangeably through the application. Collectively, they can be referred to as “undesirable materials.”
“Collapsed” or “constricted” means that at least a portion of a filter device is in a non-expanded position. The filter device or a portion thereof would normally be in a collapsed or constricted position when introduced into a vessel and/or when retained within a cover sheath of a triaxial catheter.
“Criss-cross” pattern means a wire pattern wherein the wires cross one another.
“Device”, “filter device” or “vascular filter device” means a structure for filtering in one or more vessels.
“Diameter” as used in connection with a vessel means the approximate diameter of a vessel since vessels are not often perfectly cylindrical. “Diameter” as used with respect to any structure means an approximate diameter.
“Dilated” means enlarged or expanded in width, bulk or extent.
“Expanded” means that at least a portion of a vascular filter device is in an expanded position. A vascular filter device or a portion thereof within a vessel may be expanded for the purpose of allowing fluid to substantially freely flow through the vessel.
“Expanded” and “substantially expanded” may be used interchangeably when used in connection with a filtration device. “Self-expanding” means a filter device capable of expanding on its own, without external forces.
“Filter” means a device or structure having the function of holding back or capturing a material.
“Fluid” means any substance, such as a liquid or gas, that can flow, including bodily fluids, such as blood and blood plasma.
“Offset” means the relative position between two things that may otherwise be aligned but are not aligned with one another.
“Malleable” means capable of being shaped, altered or controlled by external forces or influences. “Malleable portion” means a portion of the filter device capable of switching between a constricted and an expanded position.
“Reversible” and “reversible vascular filter device” means a device that is capable of being eliminated after a period of time such that the device remains within a vessel but does not continue to filter.
“Vessel” means any vessel within a body, such as the human body, through which blood or other fluid flows and includes arteries and veins.
“Wire” means any type of wire, strand, strut or structure, regardless of cross-sectional dimension (e.g., the cross-section could be circular, oval, or rectangular) or shape, and regardless of material, that may be used to construct a filter device as described herein. Some wires may be suitable for one or more of the embodiments but not suitable for others.
In accordance with one embodiment of the present invention, systems and methods are provided herein for capturing dislodged clots or debris (e.g., emboli) within a vessel using an implantable vascular filter device. The vascular filter device of the present invention may find use in capturing dislodged clots in, for instance, the vena cava. In various embodiments, the filter device can be bi-directional such that the device may be placed in a vessel in either direction to capture clots. In this way, the need associated with uni-directional filters to place them in a particular direction (e.g., along the blood flow) can be eliminated.
Although discussed herewith in connection with the vena cava, it should be appreciated that the device of the present invention can be adapted for use within other vessels in the body. For example, the vascular filter device of the present invention may also find use in veins and arteries, such as the abdominal aorta, aortic arch, the ascending aorta, the descending aorta, a carotid artery, an iliac artery, or a renal artery.
The vascular filter device of the present invention includes, in an embodiment, a single-piece reversible design. In other words, the reversible design of the vascular filter device of the present invention allows the device to remain within the vessel following implantation and the device can be deployed to not act as a filter, once such function is no longer necessary. By allowing the device to remain within the vessel following implantation, the vascular filter device of the present invention can reduce the likelihood of undesirable laceration, perforation or transection of the vessel walls associated with the removal process. The single-piece design may also ensure that the vascular filter device remains intact following implantation and that one of its components does not detach, as may occur if the vascular filter device were composed of more than one piece, which can damage the vessels or other organs or tissues downstream.
In the first position, the proximal portion 110 may be designed to have a sufficiently small diameter so that it can be directed along a vessel to a site of interest for implantation. Of course, the device 100 can be provided with a collapsed diameter of any size, depending on the application, size of the vessel, and so long as the diameter permits the vascular filter device to fit within a vessel for maneuvering. It should be noted that the diameter of the device 100 should also permit the device 100 to fit within any suitable catheter or other delivery mechanism for insertion into a vessel.
In a second position, where the proximal portion 110 is substantially expanded in order to engage a vessel wall and to secure itself within the vessel, the proximal portion 110 of the vascular filter device 100 can allow for the passage of fluid through pathway 160 of the device 100. In this expanded position, the vascular filter device 100 can act to minimize occlusion or hindrance of fluid flow through the vessel at a point of implantation. It should be appreciated that the vascular filter device 100 may be provided with an expanded diameter of any size, so long as the proximal portion 110 can act to push against the vessel wall at the site of interest to secure itself thereat.
To adequately secure the vascular filter device 100 within a vessel, the proximal portion 110 should be made from any material and provided with any design that can radially expand to exert a sufficient radial force to push the device 100 against the vessel wall, so as to secure the proximal portion 110 within the vessel. It should be appreciated that the material used should permit the proximal portion 110 of the device to conform to the dimensions of the vessel even when the vessel dimensions may not be uniform. In other words, the proximal portion 110 may have a diameter which can vary along the length of the proximal portion 110.
In an embodiment, the proximal portion 110 may be provided on a framework 120 arranged in any suitable geometric or non-geometric pattern, such as a zig-zag, braid, criss-cross, non-overlapping pattern, or any other pattern as the present disclosure is not intended to be limited in this manner. The pattern of the framework 120, in an embodiment, may affect the strength and/or flexibility of the vascular filter device. For instance, a braid pattern may have greater strength, while the coil pattern may have better flexibility.
As shown in
In accordance with one embodiment of the present invention, the wire providing the framework 120 with a desired pattern may have a diameter or thickness of any size, depending on the particular application, as the diameter or thickness of the wire 120 may affect the strength and/or flexibility of the vascular filter device 100.
Since the vascular filter device 100 is designed to be implanted within a vessel of a human or animal body, the vascular filter device 100 should be made from a material that is biocompatible. The biocompatibility of the material may help minimize occurrence of adverse reactions due to implantation of the vascular filter device 100 within a vessel. In some embodiments, the vascular filter device 100 can be made entirely or partially from material that is bioresorbable, or biodegradable, or a combination thereof. In such instances, the vascular filter device 100 may be entirely or partially absorbed by the vessel or may be degraded after a certain period of time has elapsed, and would eliminate the need for manual removal of the vascular filter device 100.
In an embodiment, the material from which the proximal portion 110 of the vascular filter device 100 may be formed includes metal, metal alloy, polymer, molded plastic, metal-polymer blend, or a combination thereof. The type of material may affect the strength and/or flexibility of the vascular filter device 100. Examples of suitable materials include stainless steel (e.g. type 304V), gold, platinum, tungsten, nickel-titanium alloy, Beta III Titanium, cobalt-chrome alloy, cobalt-chromium-nickel-molybdenum-iron alloy, Elgiloy, L605, MP35N, Ta-10W, 17-4PH, Aeromet 100, 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), polyetherimide (PEI), tantalum, tungsten, or any other suitable material that is biocompatible and that is capable of being expanded in the manner described above. The vascular filter device 100 may also include an anti-thrombogenic coating such as heparin (or its derivatives), urokinase, or PPack (dextrophenylalanine proline arginine chloromethylketone) to prevent thrombosis or any other adverse reaction from occurring at the site of insertion.
To enhance secured placement of the proximal portion 110 against the vessel wall, the proximal portion 110 of the vascular filter device 100 may include, in an embodiment, a securing or attachment mechanism (not shown). Examples of possible attachment mechanisms can include a hook, pin, needle, prong, barb, wedge or any other attachment mechanism adapted to adequately engage and secure the proximal portion 110 to the vessel wall. In an embodiment, the attachment mechanisms can be situated anywhere along the proximal portion 110, as the present invention is not intended to be limited in this manner. For example, the attachment mechanisms can be located at apexes 122 of the framework 120. In addition, an anti-inflammatory agent such as dexamethasone, prednisolone, corticosterone, budesonide, estrogen, sulfasalazine, mesalamine, or any suitable combination or mixture thereof may be applied to the attachment mechanism to prevent inflammation or any other adverse reaction caused by the engagement of the attachment mechanism along the vessel wall.
Still looking at
In one embodiment, the distal portion 130 may be designed to include a first position where the distal portion 130 is substantially collapsed. In this first position, the distal portion 130 has a sufficiently small diameter to permit insertion into a vessel. The distal portion 130 can also have a second position where the distal portion 130 is substantially expanded. In the substantially expanded position, the distal portion 130 can permit the flow of fluid through the vascular filter device 100 and can act to minimize any occlusion or hindrance of the flow of fluid through the vessel when filter 140 is eliminated.
In accordance with the embodiment shown in
The vascular filter device 100 can further include a pathway 160 extending from the proximal portion 110 to the distal portion 130. The presence of pathway 160 within the device 100 can permit fluid flow to enter through the proximal end 114 of the proximal portion 110, travel along the pathway 160, and exit through the distal end 134 of the distal portion 130.
Referring now to
To adequately maintain the legs 125 in a filter formation, the securing element 170 should be made from a material that is relatively strong. Additionally, the securing element 170 may be made from a material that is biocompatible. The biocompatibility of the material may help minimize occurrence of adverse reactions due to implantation of the vascular filter device 100 within a vessel.
In one embodiment, the securing element 170 can also be made from a material that allows for its subsequent elimination once the filtering function is no longer necessary. As used herein, the term “elimination” can be understood to mean manual removal of the element or otherwise. Upon elimination of the securing element 170, the plurality of legs 125 may expand radially outward, as they may be provided with shape memory capability or may be expanded by exertion of an external force. Once the legs 125 have been expanded radially outward, a substantially tubular pathway 160 can be established through the framework 120.
In one embodiment, the securing element 170 can be made from a material that is capable of being severed or broken. Such a material would allow for manual removal of the securing element 170. In another embodiment, a device can be used to break the securing element 170. For example, a device, such as an angioplasty balloon catheter, may be used to expand the securing element 170 to a point where it breaks causing the distal portion 130 to revert to a fully expanded position. In other embodiments, the securing element 170 can be made entirely or partially from material that is bioresorbable or biodegradable. In such instances, the securing element 170 may be entirely or partially absorbed by the body after a certain period of time had elapsed and would eliminate the need for manual removal of the securing element 170. Examples of suitable materials include metal, metal alloy, polyglycolic acid, polymer, plastic, or metal-polymer blend, or a combination thereof, all of which are described above in greater detail.
As shown in
To capture undesirable materials, the legs 125 within the filter portion 140, in an embodiment, may be configured so as to be sufficiently spaced from one another in order to capture undesirable materials of a certain or predetermined size. In that way, filter 140 can capture only undesirable materials of a certain or predetermined size, and direct the captured undesirable materials substantially along a predefined path towards apex 145. The undesirable materials that may be too small to be captured by legs 125 of filter 140, may be permitted to flow through the filter, as these materials can subsequently be eliminated by the natural process of the body (e.g., being degraded and absorbed). For example, as undesirable material within a fluid flow moves from proximal end 114 through framework 120, the undesirable material can be captured by at least one leg 125. In an embodiment, due to the design of legs 125, once the undesirable material is captured on a leg 125, the undesirable material can be directed along a predefined path by leg 125 toward apex 145 and toward the center of the vessel. Although described as being captured by one leg 125, it should be appreciated that the undesirable material having sufficient length can extend across two or more legs 125 and be captured by multiple legs 125.
Once the filter 140 may no longer be needed, the securing element 170 can be eliminated to permit pathway 160 to be established. Elimination of the element 170 would result in the reversion of each leg 125 in the distal portion 130 to its previous position shown in
In accordance with the embodiment shown in
As shown in
To capture undesirable materials such as clots, the continuous element 270 within the filter 240, in an embodiment, may be threaded such that adjacent arms of the element 270 may be sufficiently spaced from one another in order to capture undesirable materials of a certain or predetermined size. In that way, filter 240 can capture only undesirable materials of a certain or predetermined size, and direct the captured undesirable materials substantially along a predefined path towards distal end 234. The undesirable materials that may be too small to be captured by the arms of filter 240, may be permitted to flow through the filter, as these materials can subsequently be eliminated by the natural process of the body (e.g., being degraded and absorbed). For example, as undesirable material within a fluid flow moves from proximal end 214 through framework 205, the undesirable material can be captured by at least one arm of filter 240. In an embodiment, due to the design of the arms, once the undesirable material is captured on an arm, the undesirable material can be directed on the arm along a predefined path toward distal end 234 and toward the center of the vessel. Although described as being captured by one arm, it should be appreciated that the undesirable material having sufficient length can extend across two or more arms and be captured by multiple arms.
As shown in this embodiment, the frameworks 310 and 330 may be substantially mirror images of one another and can act to capture dislodged clots within either of framework 310 or 330. By providing the ability to capture dislodged clots in either framework, the vascular filter device 300 of the present invention can be oriented in either direction within a vessel without regard to fluid flow direction to capture dislodged clots once the filter function is no longer necessary. Although not shown in
With reference now to
In another embodiment, the vascular filter device may be made from, for instance, a single piece of material, which can be in the shape of a tube or any other geometric or non-geometric shape. The material, in one embodiment, may be a superelastic material, such as, for example, Nitinol. The material can be cut or otherwise deformed using, for instance, a laser or any other mechanism to achieve the different configurations, patterns or designs desired for the vascular device, including the eyelets. Additionally processing, such as heating, quenching, or other known methods in the art may be implemented to provide the device with the desired characteristics, including the strength, flexibility, spring force, and shape memory.
To create a filter within the distal portion of the vascular filter device, a securing element, such as, for example, a wire, suture, or cap, may be used. In an embodiment, the securing element serves to bring together the distal end of the distal portion to form a filter as shown in
Looking now at
The vascular filter device can also include opposing filters 1002 and 1003 formed from a continuous element 1004 (e.g., wire or suture) extending within pathway 1005 of framework 1001. In an embodiment, continuous element 1004 can be provided with a criss-cross pattern between a proximal portion and a distal portion about the interior of framework 1001, so as to form substantially conically shaped opposing filters 1002 and 1003. To permit the continuous element 1004 or suture to extend within the framework 1001, eyelets 1006 may be provided at designated locations on framework 1001 and through which continuous element 1004 can be directed. In an embodiment, materials from which continuous element 1004 can made include metal, metal alloy, polyglycolic acid, polymer, plastic, metal-polymer blend, or a combination thereof. It should be appreciated that although illustrated as extending from a location away from each end of framework 1001, filters 1002 and 1003 may be designed to extend from each end of frame work 1001, if so desired.
Still looking at
In operation, to prepare any of the vascular filter devices described above for insertion in the body, a user can initially collapse the vascular filter device for insertion into a delivery mechanism, for example, a catheter. Once loaded into a delivery mechanism, the delivery mechanism may be inserted into the body, and advanced along a vessel within the body (e.g. the inferior vena cava) to a site of interest for implantation. The filter device may then be removed from within the delivery mechanism and permitted to self-expand or, alternatively, a balloon catheter may be placed within the collapsed framework and expanded to expand the framework. The expansion of the device or framework allows the device to engage the wall of the vessel, as shown in
Once the filtering function is no longer necessary, it may be desirable to reverse (i.e., eliminate) the filter or filters and reestablish the pathway through the device. Reversal of the filtering function may involve elimination of the filters manually. Manual removal may include, for example, advancing into the vena cave a device capable of severing the filter or filter formation element, locating the filter or filter formation element, and severing the filter or filter formation element. Severing the filter or filter formation element may involve cutting the wires or the mechanism holding the filter in place. In another embodiment, the filter or filter formation element can be removed by permitting their resorption or degradation over a period of time.
A method of manufacturing a filter in accordance with the present invention is also provided. In some embodiments, metals, including superelastic metals, may have a hardened state. In a hardened state, the metal may be made to be self-expanding and spring-like. In other embodiments, metals, including superelastic metals, may have an annealed state. In an annealed state, the metal may be made to be deformable and malleable. A filter framework, in accordance with one embodiment, may be manufactured from a single tube. The single tube may, in an embodiment, be in an annealed state, where it is soft and malleable. The tube, for example, can then be cut using laser or other methods known in the art to yield the desired framework. Once the desired framework is produced, the malleable framework can, in an embodiment, be expanded mechanically using, for instance, a dilation balloon or other dilation device to form a filter or “butterfly” configuration. Once expanded, the tube may remain in the “butterfly” configuration. While in this configuration, the framework may, in one embodiment, be treated and processed by first heating the framework to a substantially high temperature and then quenching the framework in a low temperature fluid bath to harden the entire filter and produce spring-like properties. It should be appreciated that other methods known in the art may also be used to provide spring-like properties to the framework.
In some embodiments, it may be desired that certain portions, such as the filter arms and/or the middle portion, of the framework be malleable. Where malleability is desired, portions of the framework may be treated and processed by first heating the desired portions, and then letting the desired portions cool at a substantially slower rate, for instance, in the air. In one embodiment, the filter arms and the middle portion may be made malleable by reheating and allowing room cooling of these areas. The process of heating followed by air cooling is able to anneal and soften the filter arms and the middle portion making them malleable. Of course, other methods known in the art can also be used to treat and process the framework so as to provide malleable characteristics to the desired portions.
It should be appreciated, that although described as being formed from a single tube, the filter may be formed from multiple components that can be joined together to form a framework.
While the invention has been described in connection with the specific embodiments thereof, it will be understood that it is capable of further modification. Furthermore, this application is intended to cover any variations, uses, or adaptations of the invention, including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as fall within the scope of the appended claims.
The present application claims priority to and benefits of Provisional Application No. 61/289,508 filed Dec. 23, 2009, Provisional Application No. 61/295,457 filed Jan. 15, 2010, Provisional Application No. 61/304,155 filed Feb. 12, 2010, and Provisional Application No. 61/314,816 filed Mar. 17, 2010, the disclosures of all of which applications are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61289508 | Dec 2009 | US | |
| 61295457 | Jan 2010 | US | |
| 61304155 | Feb 2010 | US | |
| 61314816 | Mar 2010 | US |
