Patent Publication Number: US-2006020285-A1

Title: Method for filtering blood in a vessel with helical elements

Description:
FIELD AND BACKGROUND OF THE INVENTION  
      In the human cardiovascular and circulatory system, the consistency of blood remains liquid enough for the blood cells and other molecules to travel smoothly through the arteries and veins. Sometimes, however, clots will form in a process called coagulation. When clots or other blood-borne clumps of tissue migrate through the circulatory system, they are called emboli; a single migrating clot is called an embolus or an embolism.  
      A pulmonary embolism is a clot that travels through the venous system and eventually lodges in the pulmonary artery, which carries blood from the heart to the lungs. This can obstruct the blood supply to the lungs, which is potentially fatal and should be treated as an emergency.  
      Many pulmonary emboli result from a condition called deep vein thrombosis (DVT). DVT is the formation of a blood clot in the veins embedded deep in the muscles, usually in the lower leg and sometimes in the pelvis or groin.  
      Vena cava filters, tiny nets, help prevent emboli from traveling through the heart and into the lungs. Most commonly, vena cava filters are inserted into the inferior vena cava, a large vein that carries blood from the lower extremities.  
      Vena cava filters are normally metallic, umbrella-shaped devices that catch blood clots to prevent them from traveling to the lungs and causing a pulmonary embolism. Vena cava filters usually are used when drug therapy, such as treatment with blood-thinners, has failed or is considered inadequate, or when drug therapy would cause other dangerous medical conditions.  
      The procedure is safe and effectively reduces the risk of pulmonary embolism in most people when performed by a practitioner who is skilled in filter insertion and when complemented by drug therapies.  
      People most likely to receive a vena cava filter are those at risk for pulmonary embolism and those for whom drug or other therapy is considered inadequate. Vena cava filters are also inserted to protect trauma patients from pulmonary embolism associated with their injuries.  
      The procedure for placing a vena cava filter in a patient usually requires that the physician administer a local anesthetic at the insertion site, either the arm, neck, or groin, and makes an incision. Patients may also receive a muscle relaxant for additional comfort. Alternatively, the procedure may be performed while the patient is under general anesthesia.  
      The physician then inserts the collapsed filter into the incision via a catheter (a long, thin, flexible tube) and advances the filter to the vena cava. The physician then deploys the filter in the vein at the target location, removes the insertion device, and closes the incision. The procedure generally takes from 10 to 40 minutes. Antibiotics are prescribed as necessary to minimize the risk of infection.  
      Patients are likely to remain in the hospital until the supervising physician confirms that the filter is properly fixed in the vena cava and that there are no complications from the procedure. The presence of a vena cava filter does not affect daily routines or the use of other medications. Some patients may remain on anticoagulant drug therapy to reduce the risk of post-insertion clot formation, or risk enlarging a pre-existing clot.  
      However, there are known complications that may arise in any vena cava filter placement even though known vena cava filters are about 98 percent successful in preventing symptomatic pulmonary embolism. These known filter devices and their placement procedures can be associated with surgical and anesthesia complications to include: bleeding at the insertion site; anesthesia-associated complications such as an allergic reaction or breathing problems; stroke; pulmonary embolism; and clots. And, as is well known in the field, these complications are not only serious to the patient&#39;s health, but they can also be fatal.  
      Thrombosis of the inferior vena cava (IVC) filter after filter placement is frequently reported and may occur with all types of filter presently used in the field. The occurrence of thrombosis can be delayed from hours to several months after the filter placement, but seems more frequent during the first 3 months. Continued anticoagulation therapy has not been shown to prevent IVC thrombosis.  
      Studies have also shown adverse flow dynamics, such as increased pressure gradients, in the filters with high clot-trapping capacity. Accordingly a device that has a high clot capture efficiency while minimizing the potential for increased pressure gradient is desirable.  
      Accordingly, what is needed is a device and method that can further reduce these serious and fatal complications in a more reliable and predictable manner. To date, there have been no known filter devices that are designed in such a manner that can eliminate these complications on a consistent basis, particularly providing for the elimination of complications that may be attributed to pulmonary embolism and blood clots.  
      The present invention is a novel filter device and method for filtering blood in a vessel that is more highly effective in capturing clots and preventing pulmonary embolism over the known prior art devices and techniques.  
     SUMMARY OF THE INVENTION  
      The present invention is a novel filter device and novel method for filtering fluid or blood in a vessel or organ that is more highly effective in capturing clots, emboli, particulate matter and particles and preventing pulmonary embolism over the known prior art devices and techniques The device will also avoid plugging up and restricting blood flow.  
      The present invention is directed to various embodiments of devices and methods for trapping or capturing emboli in a vessel of patient&#39;s body or organ.  
      In one embodiment, the present invention is a device for capturing an embolus within a vessel of a patient&#39;s body, the device comprising: 
          at least one helix made of a mesh material, the at least one helix having a 
 
 plurality of turns helically arranged around a longitudinal axis, the mesh material having a plurality of pores therein, the pores having a size ≧120 μm. 
       

      In another embodiment, the present invention is a device for trapping an embolus within a vessel, the device comprising: 
          a plurality of mesh panels movable from a collapsed state to an expanded state when placed within a vessel, the mesh panels forming a plurality of turns helically arranged around a longitudinal axis when in the expanded state, the mesh panels having a plurality of pores therein, the pores having a size ≧120 μm.        

      In another embodiment, the present invention is a device for trapping an embolus within a vessel, the device comprising: 
          a plurality of mesh panels movable from a collapsed state to an expanded state when placed within a vessel, the mesh panels forming a plurality of turns helically arranged around a longitudinal axis in a double helix arrangement when in the expanded state, the mesh panels having a plurality of pores therein, the pores having a size ≧120 μm.        

      Another embodiment for the present invention is directed to a method for capturing an embolus within a vessel of a patient&#39;s body, the method comprising the steps of: 
          providing a device comprising at least one helix made of a mesh material, 
 
 the at least one helix having a plurality of turns helically arranged around a longitudinal axis, the mesh material having a plurality of pores therein, the pores having a size ≧120 μm; and 
    placing the device within the vessel of the patient&#39;s body.        

      The method according to the present invention further includes the step of placing the device within the vessel of the patient&#39;s body by moving the device from a collapsed state to an expanded state when placed within a vessel. Other steps include anchoring the device to an inner wall of the vessel, for instance, through using a plurality of barbs.  
      Another embodiment for the present invention is directed toward a method for capturing an embolus within a vessel of a patient&#39;s body, the method comprising the steps of: 
          providing a device comprising at least one helix made of a mesh material, the at least one helix having a plurality of turns helically arranged around a longitudinal axis, the mesh material having a plurality of pores therein, the pores having a size ≧120 μm, the pores varying in size from a larger size at one end of the at least one helix to a smaller size at an opposite end of the at least one helix; and     placing the device within the vessel of the patient&#39;s body.        

      Another method of the present invention is a method for trapping an embolus within a vessel of a patient&#39;s body, the method comprising the steps of: 
          providing a device comprising a plurality of mesh panels movable from a collapsed state to an expanded state when placed within a vessel, the mesh panels forming a plurality of turns helically arranged around a longitudinal axis when in the expanded state, the mesh panels having a plurality of pores therein, the pores having a size ≧120 μm; and     placing the device within the vessel of the patient&#39;s body.        

      The method further includes the step of placing the device within the vessel of the patient&#39;s body by moving the mesh panels of the device from a collapsed state to an expanded state when placed within a vessel and anchoring the device to an inner wall of the vessel by using an anchoring mechanism or plurality of anchoring mechanisms such as a plurality of barbs.  
      Another method for the present invention is a method for trapping an embolus within a vessel of a patient&#39;s body, the method comprising the steps of: 
          providing a device comprising a plurality of mesh panels movable from a collapsed state to an expanded state when placed within a vessel, the mesh panels forming a plurality of turns helically arranged around a longitudinal axis in a double helix arrangement when in the expanded state, the mesh panels having a plurality of pores therein, the pores having a size ≧120 μm; and     placing the device within the vessel of the patient&#39;s body.     In all embodiments of the present invention, pore sizes can vary. For instance all pore sizes can be a size ≧120 μm.Moreover, in all embodiments of the present invention, the pore sizes of the device can vary from one end of the device to an opposite end of the device.        

      For example, the pore size can vary from a larger size pore at one end of the device to a smaller size pore at an opposite end of the device wherein the pore size decreases throughout the entire length of the device, i.e. pore size decreases from the one end to the opposite end of the device such as found with depth type filter devices. The at least one helix having a plurality of turns helically arranged around a longitudinal axis can vary in pitch. This pitch may decrease to zero, to the point where the helix ends by making a full revolution and contacts itself. Additionally, in all embodiments of the present invention, the pore size can be a uniform size throughout the device, i.e. from one end of the device to the opposite end of the device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The novel features of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to organization and methods of operation, together with further objects and advantages thereof, may be understood by reference to the following description, taken in conjunction with the accompanying drawings in which:  
       FIG. 1A  is a schematic illustration of a vessel in cross-section having a s helical filter device for capturing emboli in accordance with the present invention;  
       FIG. 1B  is an enlarged illustration of a portion of the vessel and filter device of  FIG. 1  capturing emboli therein in accordance with the present invention;  
       FIG. 2A  is a schematic illustration of another embodiment of the filter device of  FIGS. 1A and 1B  in accordance with the present invention;  
       FIG. 2B  is a schematic illustration of the filter device of  FIG. 2A  having a plurality of anchoring mechanisms for securing the device to the inner wall of a vessel or organ in accordance with the present invention;  
       FIG. 3A  is a schematic illustration of another embodiment of the filter device of  FIGS. 1A and 1B  having varying pore sizes extending from one end of the device to an opposite end thereof and also including an optional spine in accordance with the present invention;  
       FIG. 3B  is a schematic illustration of the filter device of  FIG. 3A  having a plurality of anchoring mechanisms for securing the device to the inner wall of a vessel or organ in accordance with the present invention;  
       FIG. 4A  is a schematic illustration of another embodiment of the filter device of  FIGS. 1A and 1B  having a double helix design in accordance with the present invention;  
       FIG. 4B  is a schematic illustration of the filter device of  FIG. 4A  having a plurality of anchoring mechanisms for securing the device to the inner wall of a vessel or organ in accordance with the present invention;  
       FIGS. 5A, 5B  and  5 C are schematic illustrations of a manufacturing method and method for expanding the filter device of  FIGS. 1A and 1B  in accordance with the present invention; and  
       FIG. 6  is a schematic illustration of the filter device and device for delivering the filter device in accordance with the present invention.  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The present invention is a filter device, generally designated  50 , having a helical design that is either surface type filter ( FIGS. 1A, 1B ,  2 A,  2 B,  4 A and  4 B) or depth type filter ( FIGS. 3A and 3B ) that may be employed in any generally cylindrical pathway such as a vessel  10  ( FIGS. 1A and 1B ) such as a vein or artery, for example the vena cava, or a duct or an organ of the human body. The filter device  50  and method for using the device  50  is particularly useful for filtering a vena cava and more particularly useful for treatment of vascular disease such as DVT although the device  50  and method of using same is not in any way limited to this particular anatomy or disease state.  
      The filter device  50  has a helix  55  (as either a single helix or double helix as better described later on below) that is particularly useful for trapping and capturing clots, emboli, particulate matter, particles and thrombus that are migrating or circulating throughout the circulatory system of the patient or are in danger of breaking apart from attached tissue or structure within the body and migrating or circulating throughout the circulatory system of the patient. As defined herein, the term “clot”, “clots”, “embolus”, “embolism”, “emboli”, “particulate”, “particulate matter”, “matter”, “particles”, “filtrate”, “thrombus”, and “thrombi” have the same meaning for purposes of this disclosure and are used interchangeably throughout and are generally designated as reference numeral  20 .  
      The helix  55  of filter device  50  is made of a mesh material  52  having a plurality of pores  53  throughout the mesh  52 . For example, the mesh  52  consists of a plurality of interlocking strands or fibers or an array of pores  53  made and arranged in the material  52  itself such as through cutting, etching, stamping or the like. Details for the pores  53  are addressed below.  
      The material  52  is any form of material. In one embodiment, the material  52  is a self-expanding material such as shape-memory material which can be a metal alloy such as nickel titanium alloy (nitinol). In another embodiment, the material  52  is a stainless steel alloy. Alternatively, the mesh material  52  is a polymer material. The polymer can be biodegradable and/or bioabsorbable. As used herein, the term “biodegradable” is defined as the breaking down or the susceptibility of a material or component to break down or be broken into products, byproducts, components or subcomponents over time such as days, weeks, months or years. As used herein, the term “bioabsorbable” is defined as the biologic elimination of any of the products of degradation by metabolism and/or excretion.  
      The expanded shape of the filter  50  comprises at least one helix  55 , for example a single helix ( FIGS. 1A, 1B ,  2 A,  2 B,  3 A and  3 B) or a double helix ( FIGS. 4A and 4B ). The single helix  55  and double helix  55  respectively in some embodiments of the invention comprise a plurality of pleats or panels  60  helically arranged around a longitudinal axis of the device  50 . The panels  60  are helically arranged around the longitudinal axis in a plurality of helical turns  65 . The helical turns  65  define an inner diameter (ID) and an outer diameter (OD) respectively. Alternatively, the helix  55  of the device  50  is constructed of a single piece of mesh material  52  or discrete sections of mesh  52  fused or connected to each other forming the single helix or double helix ( FIGS. 4A and 4B ) of the filter device  50 . The helical turns  65  of filter device have uniform pitch, or alternatively have a variable pitch depending on the channeling effect desired by the end user.  
      It is preferable that the mesh  52  of each turn  65  is sloped, slanted, inclined or curved away from ID of helix  55  to OD of helix  55  such as depicted in the Figs., or alternatively, the helix  55  may have no incline or inclined toward the longitudinal axis. Since the mesh  52  is slanted or curved outwardly from ID to OD for each turn  65  of helix  55 , fluid medium is forced and channeled toward the outer circumferential periphery of the helix  55 . The panels  60  design for the helix  55  in the embodiments depicted in  FIGS. 1A and 1B  facilitate this outward inclined feature and outward fluid channeling effect.  
      The helix  55  has a plurality of turns  65  helically arranged around a longitudinal axis that can vary in pitch. This pitch may decrease to zero, to the point where the helix  55  ends or terminates by making a full revolution and contacts itself.  
      In some embodiments according to the present invention, the helix  55  includes a spine  57  as best illustrated in  FIGS. 3A and 3B . The spine  57  serves as a central longitudinal shaft or axis for the helical turns  65  of the helix  55 . The spine  57  is optional for the helix  55  since the helix  55  can be constructed without this feature.  
      The filter device  50  is expandable from a compressed, closed, pre-deployed or collapsed state to an open, deployed or expanded state such as partially depicted in  FIGS. 5B and 5C . For those embodiments having a plurality of panels  60  such as depicted in  FIGS. 1A and 1B , the panels  60  of mesh  52  circumferentially expand upon deployment of the device  50  as best shown by direction arrows in  FIG. 5B . The filter device  50  is introduced into a lumen  15  of the vessel  10  in the compressed, closed, pre-deployed or collapsed state and the device  50  is deployed in the lumen  15  of the vessel  10  by movable expansion of the helix  55  to the open, deployed or expanded state. When moved to the open, deployed or expanded state, the ID of the helix  55  roughly aligns along the longitudinal axis of the vessel  10  and the OD of the helix  55  is adjacent inner wall  12  of the vessel  10 .  
      Additionally, when moved to the open, deployed or expanded state, the helix  55  embeds itself in the wall  12  of the vessel  10  such as shown in  FIGS. 1A and 1B . As best illustrated in  FIGS. 2B, 3B , and  4 B, anchoring mechanisms  68 , such as a plurality of barbs  68 , are used to secure the helix  55  in tissue such as the wall  12  of vessel  10 .  
      The size for each pore  53  is ≧120 mm. Additionally, in all embodiments of the present invention, the pore size can be a uniform size throughout the entire length of the device  50 , i.e. from one end of the device  50  to the opposite end of the device  50 .  
      The filter device  50  according to the present invention (all embodiments) provides the ability to expose a greater surface area of the filter device  50  due to the unique helix  55  feature. Based on its helical design, the filter device  50  permits a smaller pore structure  53  (over the known filters and filtering methods) because the possibility of stopping venous flow is eliminated. Accordingly, smaller sized clots  20 , for instance clots  20  having a size ≧120 μm, can be targeted and captured, thereby reducing risk to the patient, i.e. the risk of these smaller size clots  20  causing harm.  
      Moreover, in all embodiments of the present invention, the pore sizes of the filter device  50  can vary from one end of the device  50  to an opposite end of the device  50 . For example, as best illustrated in  FIGS. 3A and 3B , the pore size can vary from a larger size pore at one end of the device (for example a 5 mm pore size) to a smaller size pore  53  at an opposite end of the device  50  (for example a 120 μm pore size) such that the pore size decreases throughout the entire length of the device  50 ,  25  i.e. pore size decreases from the one end to the opposite end of the device  50  thereby increasing the useful life of the device  50  such as found with depth type filter devices. The larger clots  20  are captured at the beginning of the helix  55  of filter device  50  reserving the smaller pore structure portion at opposite or far end of the helix  55  of filter device  50  to remove the smaller clots  20 .  
      The structure of the helix  55  is an expanded mesh  52  that creates the surface filter effect. Any particulate or clot  20  that approaches the filter device  50  according to the present invention encounters what appears to be a solid cylindrical impediment in the lumen  15  of vessel  10  (since OD of helix  55  circumferentially is expanded to and circumferentially conforms to inner wall  12  of vessel  10  as best shown in  FIGS. 1A and 1B ). However the helical twist of helix  55  allows lower viscosity fluid medium (such as blood) to flow through pores  53  and around the mesh  52 . Any particulate or clot  20  present in this fluid flow will impinge the mesh  52  of the helix  55  and either be trapped there, or be forced out toward the outer periphery of the helix  55  by a helical centrifugal flow effect. The helical structure of the filter device  50  according the present invention also induces outward force by the outward curvature or inclination of the mesh  52  where the particulate or clot  20  will be trapped. The fluid (blood) is free to move around and passed the clot  20 , even if the filter structure is fully covered by particulate or clots  20 .  
      There are several advantages to the helical filter design of the filter device  50  according to the present invention, for example, the ability of the helix  55  of filter device  50  to filter large amounts of filtrate (clots  20 ) and completely avoid clogging or plugging the lumen  15  of vessel  10 , i.e. vena cava  10  in this example. This is especially important since prior art filters increase the resistance in the lumen  15  of vessel  10  as they are eventually clogged or plugged by particulate matter (clots  20 ), eventually restricting the flow within vessel  10  thereby cutting off or occluding fluid flow altogether.  
      The helical filter design of filter device  50  of the present invention captures the filtrate  20  by inertial impaction, or diverts it to the outside edges or periphery of the helix  55  thereby trapping it, while allowing the fluid medium (liquid or gas) to pass around the new obstruction created by the captured filtrate  20 .  
      Other advantages of the filter device  50  of the present invention include the ability to generate a filter having different pore sizes from beginning to end as depicted in  FIGS. 3A and 3B , mimicking a depth type filter, thereby increasing the filter life. This variable pore size (along the length of the device  50 ) feature ensures that larger clots  20  will be captured at the beginning of the filter where the size of pores  53  are larger, reserving the smaller pore structure portion of the filter to remove the smaller clots  20 .  
      Other advantages for the filter device  50  of the present invention-relate to its delivery, deliverability and manufacturability. For example, as depicted in  FIG. 5A , for those embodiments of the present invention made of shape memory material, such as nickel titanium as one example, the shape memory alloy is used as the structure of the filter  50  itself and will also serve as the delivery mechanism for the filter  50  as better described below.  
      As shown in  FIG. 5A , the filter device  50  can be laser cut in the general shape of a ribbon out of a tube  40  of shape memory material (nickel titanium in this example). The final cut shape taken from shape memory tube  40  is generally akin to a ribbon as best shown in  FIG. 6 . The cut device  50  (ribbon-like at this point) is loaded onto a shaft  82  of a catheter  80  which is akin to taking a ribbon and wrapping it around a pencil. The device  50  is loaded onto shaft  82  by advancing the shaft  82  as cut device  50  is circumferentially wrapped around shaft  82  so that there is no overlap of the device  50  on itself, thereby following a helical pattern. An optional cover  85  is used for the catheter  80  to keep the wrapped and loaded device  50  compressed in its compressed, closed, pre-deployed or collapsed state.  
      One geometry, merely used as an example, is depicted in  FIGS. 5A, 5B  and  5 C, where the initial shape of device  50  appears to be cut out of a ribbon ( FIG. 5A ), but when expanded, one side/edge expands more than the other generating a circular path ( FIGS. 5B and 5C ). When the circular path is given an axial component, the helical filter shape (helix  55 ) of filter device  50  is generated.  10  Accordingly, as shown in  FIG. 6 , the filter device  50  according to the present invention provides for an extremely compact delivery method thereby providing flexibility in the delivery method. The helical shape (helix  55 , i.e. single helix or double helix design) inherently conforms to the shaft  82  of the catheter  80  and is able to achieve a tight bend radius as shown. Thus, the filter device  50  is self-centering and can easily adapt and function in a tightly constricted and bent environment.  
      Furthermore, variations for the filter device  50  are also contemplated herein according to the present invention. For example, as mentioned above, the helical turns  65  of the filter device  50  can have a variable pitch. Additionally, one end of the filter device  50  can coil in on itself, thereby providing an absolute type filter and eliminate any perception that a clot  20  may travel passed the filter  50 .  
      Moreover, the filter device  50  is optionally coated with a drug such as a cytotoxic drug or cytostatic drug in order to make the filter device  50  a drug eluting device for treatment of disease that responds to cytotoxic drugs (for example paclitaxel) or cytostatic drugs (for example one of the rapamycins) respectively. As used herein, the term “drug” or “drugs” are used interchangeably herein and define an agent, drug, compound, composition of matter or mixture thereof which provides some therapeutic, often beneficial, effect such as being cytotoxic or cytostatic as two examples.  
      This includes pesticides, herbicides, germicides, biocides, algicides, rodenticides, fungicides, insecticides, antioxidants, plant growth promoters, plant growth inhibitors, preservatives, antipreservatives, disinfectants, sterilization agents, catalysts, chemical reactants, fermentation agents, foods, food supplements, nutrients, cosmetics, drugs, vitamins, sex sterilants, fertility inhibitors, fertility promoters, microorganism attenuators and other agents that benefit the environment of use. As used herein, the terms further include any physiologically or pharmacologically active substance that produces a localized or systemic effect or effects in animals, including warm blooded mammals, humans and primates; avians; domestic household or farm animals such as cats, dogs, sheep, goats, cattle, horses and pigs; laboratory animals such as mice, rats and guinea pigs; fish; reptiles; zoo. and wild animals; and the like. The active drug that can be delivered includes inorganic and organic compounds, including, without limitation, drugs which act on the peripheral nerves, adrenergic receptors, cholinergic receptors, the skeletal muscles, the cardiovascular system, smooth muscles, the blood circulatory system, synoptic sites, neuroeffector junctional sites, endocrine and hormone systems, the immunological system, the reproductive system, the skeletal system, autacoid systems, the alimentary and excretory systems, the histamine system and the central nervous system. Suitable agents may be selected from, for example, proteins, enzymes, hormones, polynucleotides, nucleoproteins, polysaccharides, glycoproteins, lipoproteins, polypeptides, steroids, hypnotics and sedatives, psychic energizers, tranquilizers, anticonvulsants, muscle relaxants, antiparkinson agents, analgesics, anti-inflammatories, local anesthetics, muscle contractants, blood pressure medications and cholesterol lowering agents including statins, antimicrobials, antimalarials, hormonal agents including contraceptives, sympathomimetics, polypeptides and proteins capable of eliciting physiological effects, diuretics, lipid regulating agents, antiandrogenic agents, antiparasitics, neoplastics, antineoplastics, hypoglycemics, nutritional agents and supplements, growth supplements, fats, ophthalmics, antienteritis agents, electrolytes and diagnostic agents.  
      Examples of the therapeutic agents or drugs useful in this invention include prochlorperazine edisylate, ferrous sulfate, aminocaproic acid, mecaxylamine hydrochloride, procainamide hydrochloride, amphetamine sulfate, methamphetamine hydrochloride, benzphetamine hydrochloride, isoproteronol sulfate, phenmetrazine hydrochloride, bethanechol chloride, methacholine chloride, pilocarpine hydrochloride, atropine sulfate, scopolamine bromide, isopropamide iodide, tridihexethyl chloride, phenformin hydrochloride, methylphenidate hydrochloride, theophylline cholinate, cephalexin hydrochloride, diphenidol, meclizine hydrochloride, prochlorperazine maleate, phenoxybenzamine, thiethylperazine maleate, anisindione, diphenadione, erythrityl tetranitrate, digoxin, isoflurophate, acetazolamide, methazolamide, bendroflumethiazide, chlorpropamide, tolazamide, chlormadinone acetate, phenaglycodol, allopurinol, aluminum aspirin, methotrexate, acetyl sulfisoxazole, hydrocortisone, hydrocorticosterone acetate, cortisone acetate, dexamethasone and its derivatives such as betamethasone, triamcinolone, methyltestosterone, 17-.beta.-estradiol, ethinyl estradiol, ethinyl estradiol 3-methyl ether, prednisolone, 17-.beta.-hydroxyprogesterone acetate, 19-nor-progesterone, norgestrel, norethindrone, norethisterone, norethiederone, progesterone, norgesterone, norethynodrel, indomethacin, naproxen, fenoprofen, sulindac, indoprofen, nitroglycerin, isosorbide dinitrate, propranolol, timolol, atenolol, alprenolol, cimetidine, clonidine, imipramine, levodopa, chlorpromazine, methyldopa, dihydroxyphenylalanine, theophylline, calcium gluconate, ketoprofen, ibuprofen, atorvastatin, simvastatin, pravastatin, fluvastatin, lovastatin, cephalexin, erythromycin, haloperidol, zomepirac, ferrous lactate, vincamine, phenoxybenzamine, diltiazem, milrinone, captropril, mandol, quanbenz, hydrochlorothiazide, ranitidine, flurbiprofen, fenbufen, fluprofen, tolmetin, alclofenac, mefenamic, flufenamic, difuninal, nimodipine, nitrendipine, nisoldipine, nicardipine, felodipine, lidoflazine, tiapamil, gallopamil, amlodipine, mioflazine, lisinopril, enalapril, captopril, ramipril, enalaprilat, famotidine, nizatidine, sucralfate, etintidine, tetratolol, minoxidil, chlordiazepoxide, diazepam, amitriptylin, and imipramine. Further examples are proteins and peptides which include, but are not limited to, insulin, colchicine, glucagon, thyroid stimulating hormone, parathyroid and pituitary hormones, calcitonin, renin, prolactin, corticotrophin, thyrotropic hormone, follicle stimulating hormone, chorionic gonadotropin, gonadotropin releasing hormone, bovine somatotropin, porcine somatropin, oxytocin, vasopressin, prolactin, somatostatin, lypressin, pancreozymin, luteinizing hormone, LHRH, interferons, interleukins, growth hormones such as human growth hormone, bovine growth hormone and porcine growth hormone, fertility inhibitors such as the prostaglandins, fertility promoters, growth factors, and human pancreas hormone releasing factor.  
      Moreover, drugs or pharmaceutical agents useful for the filter device  50  include: antiproliferative/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 and idarubicin), anthracyclines, mitoxantrone, bleomycins, plicamycin (mithramycin) and mitomycin, enzymes (L-asparaginase which systemically metabolizes L-asparagine and deprives cells which do not have the capacity to synthesize their own asparagine); antiplatelet agents such as G(GP)II b III a  inhibitors and vitronectin receptor antagonists; antiproliferative/antimitotic alkylating agents such as nitrogen mustards (mechlorethamine, cyclophosphamide and analogs, melphalan, chlorambucil), ethylenimines and methylmelamines (hexamethylmelamine and thiotepa), alkyl sulfonates-busulfan, nirtosoureas (carmustine (BCNU) and analogs, streptozocin), trazenes—dacarbazinine (DTIC); antiproliferative/antimitotic antimetabolites such as folic acid analogs (methotrexate), pyrimidine analogs (fluorouracil, floxuridine, and cytarabine), purine analogs and related inhibitors (mercaptopurine, thioguanine, pentostatin and 2-chlorodeoxyadenosine{cladribine}); platinum coordination complexes (cisplatin, carboplatin), procarbazine, hydroxyurea, mitotane, aminoglutethimide; hormones (i.e. estrogen); anticoagulants (heparin, synthetic heparin salts and other inhibitors of thrombin); fibrinolytic agents (such as tissue plasminogen activator, streptokinase and urokinase), aspirin, dipyridamole, ticlopidine, clopidogrel, abciximab; antimigratory; antisecretory (breveldin); antiinflammatory: such as adrenocortical steroids (cortisol, cortisone, fludrocortisone, prednisone, prednisolone, 6α-methylprednisolone, triamcinolone, betamethasone, and dexamethasone), non-steroidal agents (salicylic acid derivatives i.e. aspirin; para-aminophenol derivatives i.e. acetominophen; indole and indene acetic acids (indomethacin, sulindac, and etodalac), heteroaryl acetic acids (tolmetin, diclofenac, and ketorolac), arylpropionic acids (ibuprofen and derivatives), anthranilic acids (mefenamic acid, and meclofenamic acid), enolic acids (piroxicam, tenoxicam, phenylbutazone, and oxyphenthatrazone), nabumetone, gold compounds (auranofin, aurothioglucose, gold sodium thiomalate); immunosuppressives: (cyclosporine, tacrolimus (FK-506), sirolimus (rapamycin), azathioprine, mycophenolate mofetil); angiogenic agents: vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) platelet derived growth factor (PDGF), erythropoetin,; angiotensin receptor blocker; nitric oxide donors; anti-sense oligionucleotides and combinations thereof; cell cycle inhibitors, mTOR inhibitors, growth factor signal transduction kinase inhibitors, chemical compound, biological molecule, nucleic acids such as DNA and RNA, amino acids, peptide, protein or combinations thereof.  
      It is to be understood that the use of the term “drug” or drugs” includes all derivatives, analogs and salts thereof and in no way excludes the use of two or more such drugs.  
      The one or more drugs are coated on the filter device  50  itself or any desired portion of the device  50 , for example, the outer circumferential edge of the helical turns  65 . Moreover, the drug can be used with a polymer coating or the drug can be incorporated into the mesh material  52  of the device  50  itself when the mesh material  52  itself is made of a polymer material as mentioned above.  
      As shown in  FIGS. 2B, 3B  and  4 B, the filter device  50  alternatively has anchoring mechanisms  68  such as sharp edges or barbs along the outside periphery of the helix  55 , i.e. the turns  65 , in order to facilitate securing or anchoring into the vascular wall  12 . Additionally, it is also contemplated that the device  50  according to the present invention have any other types of attachment mechanisms suited to the intended environment.  
      As mentioned above, the deployment mechanism for the filter device  50  may be due to the material  52  itself (when the material  52  is shape-memory material) and will be in the form of a helically wrapped tube ( FIG. 6 ) or a compressed disc (not shown). The delivery device may be a structure solely made up of the compressed filter device  50  itself or alternatively the filter device  50  may be inserted in a delivery mechanism (e.g. a delivery tube or catheter  80  wherein the filter device is loaded in a compressed state between the shaft  82  and cover  85  of the catheter  80 ).  
      The mesh material  52  may be of any form, i.e. from a self-expanding material such as nitinol to a stainless steel material requiring a delivery mechanism to form it into its final shape, or it may be a polymer or blend of polymers, to name a few examples. The filter device is also made to be retractable (if desired). For instance, due to the nature of the helix design, by applying a twisting action reverse (reverse torque) to that which expanded the filter device when originally deployed in the vessel  10 , the filter device  50  can be collapsed and retracted and withdrawn from the vessel  10  and the patient&#39;s body. The material  52  can also be of the type that requires a delivery mechanism to form filter device  50  into its final helical shape.  
      In as much as the foregoing specification comprises preferred embodiments of the invention, it is understood that variations and modifications may be made herein, in accordance with the inventive principles disclosed, without departing from the scope of the invention.  
      While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will now occur to those skilled in the art without departing from the invention. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.