Abstract:
The present invention relates generally to devices for filtering embolic debris from a blood vessel in conjunction with a medical procedure. More particularly, the invention includes a loading tool for loading a filter into a sheath. In addition, a method of using the loading tool to load a filter into a sheath is disclosed.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to distal protection devices. More particularly, the present invention relates to devices for loading a distal protection filter into a delivery sheath in order to simplify delivery of the filter to an area of interest.  
         BACKGROUND OF THE INVENTION  
         [0002]    Heart disease is a major problem in the United States and throughout the world. Conditions such as atherosclerosis result in blood vessels becoming blocked or narrowed. This blockage can result in lack of oxygenation to the heart, which has significant consequences since the heart muscle must be well oxygenated in order to maintain its blood pumping action.  
           [0003]    Occluded, stenotic, or narrowed blood vessels may be treated with a number of relatively non-invasive medical procedures including percutaneous transluminal angioplasty (PTA), percutaneous transluminal coronary angioplasty (PTCA), and atherectomy. Angioplasty techniques typically involve the use of a balloon catheter. The balloon catheter is advanced over a guidewire such that the balloon is positioned adjacent a stenotic lesion. The balloon is then inflated and the restriction of the vessel is opened. During an atherectomy procedure, the stenotic lesion may be mechanically cut away from the blood vessel wall using an atherectomy catheter.  
           [0004]    During angioplasty and atherectomy procedures, embolic debris can be separated from the wall of the blood vessel. If this debris enters the circulatory system, it could block other vascular regions including the neural and pulmonary vasculature. During angioplasty procedures, stenotic debris may also break loose due to manipulation of the blood vessel. Because of this debris, a number of devices termed distal protection devices have been developed to filter out this debris.  
           [0005]    Typical distal protection devices generally comprise a filter that is disposed on a guidewire. To facilitate delivery of the filter to an area of interest, the filter may be loaded into a delivery sheath. The sheath may then be maneuvered through the vasculature to a position downstream of a medical procedure that may generate embolic debris. The sheath may then be withdrawn from the filter and the filter may be expanded in order to capture the debris.  
           [0006]    The filter may need to be substantially compressed within the delivery sheath in order for it to be passed through the narrow vasculature. Prepackaging of filters during manufacturing may lead to high filter deployment forces due to sheath/filter interactions and the effects of sterilization and aging of the product. A need, therefore exists, for a device that can minimize deployment forces by controlling sheath/filter interactions and the effects of sterilization and aging.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention pertains to a loading tool for loading a filter into a delivery sheath. The loading tool may help limit deployment forces by allowing a clinician to load the filter into the sheath. In addition, the loading tool may be used to load other objects including stents and balloons.  
           [0008]    The loading tool may comprise a proximal end, a distal end, and a lumen extending therethrough. The loading tool generally tapers proximally and may include an inside diameter that is smaller near the proximal end.  
           [0009]    The loading tool may be coupled to a delivery sheath in order to facilitate loading of the filter into the sheath. While coupled to the delivery sheath, the filter disposed proximate a distal end of an elongate shaft may be urged proximally by applying force to the elongate shaft. As the filter moves proximally, it may shift from an expanded configuration to a collapsed configuration. The filter in the collapsed configuration may be urged into a lumen of the delivery sheath. The loading tool may then be uncoupled from the delivery sheath. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a cross sectional view of a loading tool coupled to a delivery sheath, the loading tool having a filter disposed therein;  
         [0011]    [0011]FIG. 2 is a cross sectional view of the loading tool coupled to the sheath, the loading tool having the filter partially collapsed and disposed therein;  
         [0012]    [0012]FIG. 3 is a cross sectional view of the loading tool coupled to the sheath, the sheath having the filter collapsed and disposed therein;  
         [0013]    [0013]FIG. 4 is a cross sectional view of the loading tool detached from the sheath, the sheath having the filter collapsed and disposed therein; and  
         [0014]    [0014]FIG. 5 is a cross sectional view of an alternate loading tool coupled to the sheath, the loading tool having the filter partially collapsed and disposed therein. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    The following description should be read with reference to the drawings wherein like reference numerals indicate like elements throughout the several views. The detailed description and drawings represent select embodiments and are not intended to be limiting.  
         [0016]    [0016]FIG. 1 is a cross sectional view of a loading tool according to a preferred embodiment of the invention. A loading tool  10  may be used to load a filter  12  into a delivery sheath  14 . Loading tool  10  includes a proximal end  16 , and distal end  18 , and a lumen  20  extending therethrough. Loading tool  10  may be generally conical in shape and may taper at proximal end  16 . Preferably, loading tool  10  has a substantially constant wall thickness and, thus, the width of lumen  20  tapers near proximal end  16 . According to this embodiment, loading tool  10  has a first inside diameter region  22  near distal end  18  and a second inside diameter region  24  near proximal end  16 . The inside diameter of loading tool  10  at first inside diameter region  22  is greater than the inside diameter of loading tool  10  at second inside diameter region  24 . For example, the inside diameter of loading tool  10  may be about 0.08 to 0.10 inches proximate first inside diameter region  22  and may be about 0.043 to 0.08 inches proximate second inside diameter region  24 .  
         [0017]    Loading tool  10  is preferably manufactured from hypodermic tubing. Alternatively, loading tool  10  may be manufactured from materials including, but not limited to, metals, stainless steel, nickel alloys, nickel-titanium alloys, thermoplastics, high performance engineering resins, fluorinated ethylene propylene (FEP), polymer, polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane, polytetrafluoroethylene (PTFE), polyether block amide (PEBA), polyether-ether ketone (PEEK), polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polysufone, nylon, perfluoro(propyl vinyl ether) (PFA), and combinations thereof.  
         [0018]    Manufacturing of loading tool  10  may include flaring one end of hypodermic or another type of tubing. For example, extruded tubing with an inside diameter of about 0.043 inches may be flared at one end. Alternatively, a portion of a tube may be necked down over a mandrel. For example, an extruded tube may be necked down over a mandrel having an outside diameter of about 0.043 inches. In an second alternative, loading tool  10  may be manufactured by molding material to the desired shape.  
         [0019]    Filter  12  is coupled to a shaft  26  having a proximal end  28  and a distal end  30 . Filter  12  is coupled to shaft  26  proximate distal end  30 . In addition, filter  12  may include a plurality of ribs or struts  25  that bridge filter  12  and shaft  26  and may help to support and/or collapse filter  12 . Shaft  26  may be a guidewire and is preferably comprised of for example, metals including stainless steel, nickel alloys, and nickel-titanium alloys.  
         [0020]    Filter  12  operates between a closed collapsed profile, adapted for insertion into delivery sheath  14 , and an open radially-expanded deployed profile for collecting debris in a body lumen. Filter  12  may include a collapsible proximally-tapered frame having a mouth and a plurality of longitudinally-extending ribs. In an expanded profile, the mouth is opened and the ribs extend radially outwardly to support the mouth.  
         [0021]    Filter  12  may be generally cone-shaped, and have a proximal and a distal end. The distal end is a narrow, “V”-shaped end and is preferably fixedly secured or formed to shaft  26 . The proximal end has a relatively wide opening. Alternatively, filter  12  may be cylindrical with a relatively rounded distal end.  
         [0022]    Filter  12  may include a filtering mesh formed of a polymer membrane and including a plurality of small openings. For example, filter  12  may be constructed of a polyurethane sheet, and the openings may be formed in the polyurethane sheet by known laser techniques. Holes or openings are sized to allow blood flow therethrough but restrict flow of debris or emboli floating in the body lumen or cavity.  
         [0023]    Delivery sheath  14  has a proximal end  32 , a distal end  34 , and a lumen  36  extending therethrough. Shaft  26  can be disposed within lumen  36 . Delivery sheath  14  may be comprised of metals similar to those listed above for loading tool  10 .  
         [0024]    Proximal end  28  of shaft  26  and proximal end  32  of delivery sheath  14  may be coupled to a manifold  38 . Manifold  38  may include means for securing shaft  26  relative to delivery sheath  14 . Securing shaft  26  relatively to delivery sheath  14  may allow delivery sheath  14  to be urged proximally in order to deploy filter  12 .  
         [0025]    Shaft  26 , delivery sheath  14 , and filter  12  may be disposed within a package  39 . Package  39  may be sterile and may be an appropriate configuration for delivery of the product to a clinician. Additionally, loading tool  10  may be disposed within package  39 . According to this embodiment, use of loading tool  10  may include the steps of removing shaft  26 , delivery sheath  14 , filter  12 , and loading tool  10  from package  39 . Then filter  12  would be placed in sheath  14 .  
         [0026]    [0026]FIG. 2 is a cross sectional view of loading tool  10  coupled to delivery sheath  20 , wherein filter  12  is partially collapsed within loading tool  10 . Filter  12  may be urged proximally by applying force to shaft  26  or other suitable means. When filter  12  moves proximally, due to this force, the position of filter  12  relative to loading tool  10  shifts to a region (e.g., second inside diameter region  24 ) where the inside diameter within loading tool  10  becomes smaller. This results in a partial collapse of filter  12 . According to this embodiment, as filter  12  moves proximally, it may shift from an expanded configuration to a collapsed configuration.  
         [0027]    Loading tool  10  is adapted to be coupled to delivery sheath  14 . For example, loading tool  10  may be coupled to delivery sheath  14  by a friction fit. According to this embodiment, at least a portion of loading tool  10  is disposed over delivery sheath  14 . Loading tool  10  may be uncoupled (i.e., separated) from delivery sheath  14  by applying force in opposing directions to each element. Alternative ways of coupling loading tool  10  to sheath  14  may be used without departing from the spirit of the invention. For example, adhesives, heat bonds, mechanical fittings, luer fitting, and alternative means may be used.  
         [0028]    [0028]FIG. 3 depicts filter  12  collapsed and disposed within delivery sheath  14 . When filter  12  reaches a position proximate second inside diameter region  24  of loading tool  10 , filter  12  may be suitably collapsed for entry into lumen  36  of delivery sheath  14 . Filter  12  may be urged into lumen  36  by applying force to shaft  26  or other suitable means.  
         [0029]    [0029]FIG. 4 is a plan overview of loading tool  10  detached from delivery sheath  14 . When filter  12  is collapsed and disposed within lumen  36  of delivery sheath  14 , loading tool  10  may be uncoupled from delivery sheath  14 . Uncoupling of loading tool  10  from delivery sheath results in filter  12  being appropriately prepared for entry into a blood vessel (e.g., the vasculature of a patient).  
         [0030]    [0030]FIG. 5 is plan overview of an alternate loading tool. Loading tool  110  is substantially similar to loading tool  10  except that it further comprises a notched region  40  defining a third inside diameter region  42 . Loading tool  110  includes proximal end  116 , distal end  118 , lumen  120  extending therethrough, first inside diameter region  122 , and second inside diameter region  124 . Preferably, the inside diameter of loading tool  110  at third inside diameter region  42  is greater than the inside diameter of loading tool  110  at second inside diameter region  124 . For example the third inside diameter may be substantially equal to the outside diameter of delivery sheath  14 .  
         [0031]    Notched region  40  may provide a smooth transition between inside diameters of loading tool  110  and delivery sheath  14 . According to this embodiment, the inside diameter of loading tool  110  at third inside diameter region  42  may be substantially equal to the outside diameter of delivery sheath  14 . Therefore, loading tool  110  may be coupled to delivery sheath  14  by disposing third inside diameter region  42  over delivery sheath  14 . In addition, the inside diameter of loading tool  110  at second inside diameter region  124  may be substantially equal to the inside diameter of delivery sheath  14 . Therefore, filter  12  may easily move from lumen  120  of loading tool  110  into lumen  36  of sheath  14 .  
         [0032]    It should 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 steps without exceeding the scope of the invention. The invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.