Abstract:
A distal protection device that may include a guidewire having a proximal end and a distal end, a filter disposed on the guidewire, the filter including filtering material and an expandable hollow coil, and a wire at least partially disposed within the coil, wherein the filter is actuatable from a closed position to an open position by reducing tension on the wire and methods of use thereof.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 60/805,824, entitled “SELF-OPENING FILTER WITH WIRE ACTUATION,” filed Jun. 26, 2006, the entirety of which is herein incorporated by reference. 
     
     FIELD 
       [0002]    The invention pertains to the field of percutaneous filters such as intravascular filters and more particularly to expandable or actuatable percutaneous filters and methods of use thereof. 
       BACKGROUND 
       [0003]    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 of the heart, which has significant consequences since the heart muscle must be well oxygenated in order to maintain its blood pumping action. 
         [0004]    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. 
         [0005]    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, both of which are highly undesirable. 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. There is an ongoing need for new and improved distal protection devices. 
       SUMMARY 
       [0006]    One embodiment pertains to a distal protection device that includes a guidewire having a proximal end and a distal end, a filter disposed on the guidewire, the filter including filtering material and an expandable hollow coil, and a wire at least partially disposed within the coil, wherein the filter is actuatable from a closed position to an open position by reducing tension on the wire. The coil includes a plurality of loops and wherein the loops are spaced apart in the open position of the filter and spaced closer together in the closed position and the loops may abut in the closed position. The filtering material may define a proximally facing cavity having a mouth where the coil is attached to the mouth. Alternatively the coil may spiral along a portion of the length of the filtering material where the coil has a proximal end attached to the filtering material proximal end and a distal end attached to the guidewire. In another embodiment, the coil may have a helical shape and have a proximal end attached to the filtering material proximal end and a distal end attached to the guidewire proximate the filtering material distal end. The coil loops may be made form a nickel-titanium alloy such as nitinol or another suitable alloy such as a superelastic alloy or a spring steel alloy and may have a circular cross-section or a rectangular cross-section. One end of the coil may be fixed to the guidewire and one end may be fixed only to the filtering material or both ends of the coil may be fixed to the guidewire. The device may include a slider tube disposed on the guidewire to which the filter is attached, a stop disposed proximal of the slider tube and a stop distal the slider tube. The guidewire may be solid or hollow or have a solid portion and an hollow portion such as a solid distal portion of approximately 120 centimeters in length and a hollow proximal portion. For those embodiments where the guidewire has a hollow portion, the guidewire may include an opening from the guidewire lumen proximal the filter where the wire is threadably disposed through the opening and into the guidewire lumen. The wire may include a weakness such as a knot, a neck or a perforation. If the weakness is a knot the guidewire may define an opening distal a lumen in which the wire is partially disposed, and where the opening is just proximal the knot and smaller than the knot; the guidewire may include a collar in which the opening is defined. The wire may be a polymeric member, a metallic member or other suitable member. The wire may be a component having high tensile strength and low columnar strength such as a fiber or a string. For example the wire may be a Kevlar string. 
         [0007]    One embodiment pertains to a method of use in which the steps may include providing a filter disposed on a guidewire, the filter having filtering material attached to a hollow coil, providing a wire in tension disposed partially in the coil, the wire tension keeping the coil in a compacted configuration, and releasing the tension in the wire to allow the coil to expand to an open configuration and thereby open the filter. The step of releasing the tension in the wire may include the step of moving the wire distally relative to the guidewire or, where the wire comprises a distal section connected by a weakness to a proximal section, the step of releasing the tension may include the step of separating the proximal portion from the distal portion. Where the weakness is a knot, this step may include forcing a knot in the wire against a surface of the guidewire until the wire separates. This step may alternatively include the step of releasing the tension includes the step of pulling the wire proximally. 
         [0008]    Another embodiment pertains to a distal protection device that may include an elongate member having a proximal end and a distal end, a filter disposed on the elongate member, the filter including a filtering material connected to a hollow expandable coil, the filter actuatable between a collapsed configuration and an expanded configuration, the coil having a first end and a second end and defining a lumen therebetween, and a wire threaded through the lumen of the coil, the wire being attached to the first end and extending out from the second end. The coil includes a plurality of loops that are spaced apart when the filter is in the expanded configuration and spaced more closely together when the filter is in the collapsed configuration, which loops may abut when the filter is in the collapsed configuration. The filter is actuatable between the expanded configuration and the collapsed configuration by the application of tension to the wire. For example the filter may be moved from the expanded configuration to the collapsed configuration by pulling the wire proximally. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings in which. 
           [0010]      FIG. 1A  is an orthogonal diagrammatic view of the distal portion of an embodiment in a first configuration; 
           [0011]      FIG. 1B  is an orthogonal diagrammatic partial view of the embodiment of claim  1  in the first configuration; 
           [0012]      FIG. 2A  is an orthogonal diagrammatic view of the distal portion of an embodiment of claim  1  in a second configuration; 
           [0013]      FIG. 2B  is an orthogonal diagrammatic partial view of a portion of the embodiment of claim  1  in the second configuration; 
           [0014]      FIG. 3  is an orthogonal diagrammatic view of the distal portion of a second embodiment in a first configuration; and 
           [0015]      FIG. 4  is an orthogonal diagrammatic view of the distal portion of the embodiment of  FIG. 3  in a second configuration. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    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. 
         [0017]    Referring now to  FIG. 1A , which is an orthogonal diagrammatic view of the distal portion of a distal protection device  10 , a filter  12  disposed on a guide wire  28  is shown. Filter  12  includes a ring-shaped coil  16  which is biased into this open, expanded shape and which holds open the proximal mouth of filtering material  14 . Coil  16  is mounted on spinner tube  20  which is slidably disposed on guide wire  28  and prevented from sliding proximally by stop  22  and which may be optionally prevented from sliding distally by stop  24 . A wire  18  is threaded through guide wire  28 , which is hollow and through coil  16 , which is hollow as well, and is attached to the end of coil  16 .  FIG. 1B , which is an orthogonal diagrammatic view of a portion of distal protection device  10 , illustrates coil  16  in greater detail. Coil  16  comprises several loops  30  that are spaced apart from each other and to which filtering material  14  is attached. 
         [0018]    The filter may be actuated to the closed position by moving wire  18  proximally relative to the filter. When wire  18  is pulled, coil  16  may be collapsed flat against spinner tube  20  as is shown in  FIG. 2A , which is an orthogonal diagrammatic view of the distal portion of distal protection device  10 . As may be more easily seen in  FIG. 2B , the wire  18  collapses the filter by moving the loops  30  of the coil  16  closer together. If the tension on wire  18  is removed, the coil  16  will expand back to the shape depicted in  FIG. 1A . 
         [0019]    A second embodiment is depicted in  FIG. 3 , which is an orthogonal diagrammatic view of a distal protection device  32 . A filter  12  is made of a filtering material  14  attached at its distal end to guide wire  38  and a coil  16  that is disposed within filtering material  14  and attached at its proximal end to the filtering material and at its distal end to the guide wire. A wire  18  is threaded through coil  16  and tension on the wire keeps coil  16  against guidewire  38 . Coil  16  is similar to that of the previous embodiments and is made of loops (not pictured) kept by the operation of the wire close against the guide wire  38 . The wire  18  may have a knot  34  and may be threaded through an opening  40  in a collar  36 , where the knot cannot pass through the opening. This distal protection device may be actuated by pulling on wire  18 , forcing knot  34  against collar  36  and breaking the wire at that point. All tension being thereby removed from the distal portion of the wire, coil  16  expands, expanding filter  12  to its open position as shown in  FIG. 4 , where the loops of the coil are expanded from each other. Knot  34  may be a perforation or neck or other weakness in the wire. In some embodiments, collar  40  is not necessary. In some embodiments, there is no weakness such as knot  34  and the filter is expanded by releasing wire  18  as in the previous embodiment. Wire  18  need extend all the way through coil  16  which can be self expanding. 
         [0020]    These two embodiments illustrate the invention generally, but the invention is by no means limited to that discussed above. The guidewire may be a hollow hypotube or a solid shaft and in the first instance the wire may or may not be threaded through the guidewire. In one embodiment, the guide wire may have a solid proximal portion and a hollow distal portion. The wire may in this embodiment be threaded through the hollow distal portion. The wire may be any material having suitable flexibility and tensile strength. It may be, for instance, a polymer string such as a Kevlar fiber. The filtering material may be any suitable filtering material; it may be a mesh or weave made from nitinol or polymer threads; it may be a polymer sheet having holes cut or drilled therein to provide a means of filtering particles of a desired size from the blood stream. The coil may be made from superelastic nitinol or other suitable alloy capable of suitable deformation. Some spring steels may be suitable, for instance. The wire used in the coil may have a circular cross-section, a rectangular cross section or other suitable cross-section. The stops may be metal or polymeric bumps welded to or adhered to the guidewire. 
         [0021]    Distal protection devices having coils of varying configurations are contemplated. For instance, in the device of  FIG. 1 , both ends of the coil may be attached to the slider tube; in this case when the coil is collapsed by the operation of the wire the loops would form two rows. In another example variation, the coil and the filtering material could be configured to envelope the slider tube with both ends of the coil attached to the slider tube; in this case the coil would form a smaller coil in contact with the surface of the slider tube when collapsed. 
         [0022]    The embodiments of this invention may be used with other devices. For example, the device may be delivered to the area of interest in a delivery sheath and collected by a retrieval sheath. Other therapy catheters such as stent delivery catheters and angioplasty catheters may be delivered over the device. Further, other components such as radiopaque bands and atraumatic distal tips may be used with embodiments of this invention. In short, the embodiments of this invention are distal protection devices and may be used with components and other devices typically used with such devices. 
         [0023]    Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood, however, 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. None of the description in the present application should be read as implying that any particular element, step, or function is an essential element which must be included in the claim scope. Moreover, none of these claims are intended to invoke 35 U.S.C. § 112, ¶6 unless the exact words “means for” are followed by a participle. The invention&#39;s scope is, of course, defined in the language in which the appended claims are expressed.