Methods and devices for filtering fluid flow through a body structure

Abstract

An intravascular filter having a filament which expands a filter element. The filament is a coil which is stretched to reduce the diameter of the coil for introduction. The filter element is preferably biased toward the closed position and is opened by the coil when tension is released on the coil. The filament slides along the internal surface of the filter element so that the filter element may assume intermediate positions.

1 - 26 . (canceled) 
   
   
       27 . A device for filtering fluid flow through a body structure, comprising:
 a filter element movable from a collapsed position to an expanded position, the filter element being biased toward the collapsed position; and   a coil operatively coupled to the filter element, the coil having an expanded shape and a collapsed shape, the coil also being movable from a collapsed position to an expanded position, the coil sliding along the interior surface of the filter element when the coil expands to the expanded position.   
   
   
       28 . The filtering device of  claim 27 , wherein:
 the coil is free to slide against the interior surface of the filter element at all locations proximal to a distal end of the coil.   
   
   
       29 . The filtering device of  claim 28 , wherein:
 the coil has an decreasing diameter distally when in the expanded position.   
   
   
       30 . The filtering device of  claim 27 , wherein:
 the filter element is moved to the expanded position by only the coil.   
   
   
       31 . The filtering device of  claim 27 , wherein:
 the filter element is attached to a core element and extends around a portion of the core element in the collapsed position; and   the expandable element is attached to the core element.   
   
   
       32 . The filtering element of  claim 27 , wherein:
 the core and coil are expand independently in a longitudinal direction when the coil moves from the collapsed to expanded positions.   
   
   
       33 . The filtering element of  claim 27 , wherein:
 at least a part of the filter element is biased toward the collapsed position.   
   
   
       34 . The filtering element of  claim 33 , wherein:
 a proximal part of the filter element is biased toward the collapsed position.   
   
   
       35 . The filtering element of  claim 27 , wherein:
 the proximal part of the filter element is biased toward the collapsed position by a ring around a proximal end of the filter element.   
   
   
       36 . The filtering element of  claim 27 , wherein:
 the filter element is an elastomeric membrane having openings therein when in the expanded position.   
   
   
       37 . The filtering element of  claim 27 , wherein:
 the filter element is a mesh structure.   
   
   
       38 . A method of filtering blood flow through a vessel, comprising the steps of:
 providing a filter device having a filter element and an expandable element, the filter element having an interior surface, the filter element being configured to permit blood flow therethrough while filtering embolic material when in the expanded position;   introducing the filter device into a blood vessel of a patient;   advancing the filter device to a desired location; and   expanding the expandable element after the advancing step, the expanding element sliding along the interior surface of the filter element.   
   
   
       39 . The method of  claim 38 , wherein:
 the providing step is carried out with the expandable element being free to move relative to the filter element at all locations proximal to the distal end of the filter element.   
   
   
       40 . The method of  claim 38 , wherein:
 the providing step is carried out with the expandable element being not attached to the filter element at all locations proximal to the distal end of the filter element.   
   
   
       41 . The method of  claim 38 , wherein:
 the expanding step is carried out by releasing tension on the expandable member.   
   
   
       42 . The method of  claim 39 , further comprising the step of:
 compressing the expandable member to further expand the expandable element.   
   
   
       43 . The method of  claim 39 , wherein:
 the providing step is carried out with the expandable element contained within a sheath in the collapsed position.   
   
   
       44 . The method of  claim 43 , wherein:
 the providing step is carried out with the filter element having a proximal end which is positioned around the sheath when the filter element is in the collapsed position.