Temporary vascular filter

Abstract

The present invention provides a method of deploying a medical filter within a channel in a patient's body and filter systems which can be used in such a method. Such a filter may include a radially expandable body 52 having an opening 56 in a proximal length thereof. In one method, the filter is urged along a length of the channel with the filter body in a radially reduced configuration. This body is expanded to substantially fill the lumen of the vessel and orient the opening in the body proximally. Body fluid is permitted to enter the filter body through the proximally oriented opening and pass distally through the distal length of the body so that the distal length of the body filters from the body fluid particulate material entrained therein. The proximal length of the body can be drawn into the retrieval catheter, thereby effectively closing the proximally oriented opening within the catheter to retain the particulate material within the enclosure. In a preferred embodiment, the filter body 52 is formed of a porous, resilient fabric having pores therein and the proximal opening 56 is at least five times the size of such pores.

What is claimed is:  
     
         1 . A method of deploying a medical filter within a channel in a patient's body, the method comprising: 
 a) providing a filter having a radially expandable body having proximal and distal ends and defining an enclosure, the body having a distal length and a proximal length which has an opening therein; and a retrieval catheter having a lumen with a diameter less than a maximum dimension of the body's expanded configuration;    b) urging the filter along a length of the channel with the filter body in a radially reduced configuration;    c) radially expanding the body to its expanded configuration such that it substantially fills the lumen of the vessel and the opening in the body is oriented proximally;    d) permitting body fluid to enter the enclosure through the proximally oriented opening and pass distally through the distal length of the body, the distal length of the body filtering from the body fluid particulate material entrained therein; and    e) drawing the proximal length of the body within the lumen of the retrieval catheter, thereby effectively closing the proximally oriented opening within the catheter to retain said particulate material within the enclosure.    
     
     
         2 . The method of  claim 1  wherein the proximal length of the filter's body tapers proximally to a narrow proximal end which is smaller than the lumen of the catheter, the step of drawing the proximal length within the catheter comprising receiving a narrow proximal end of the body in the lumen of the catheter then retracting the filter until the internal surface of the catheter engages the body of the filter distally of the opening to effectively create a particulate seal therebetween.  
     
     
         3 . The method of  claim 2  wherein the narrow proximal end of the body is spaced from a wall of the vessel when the filter is expanded into its expanded configuration.  
     
     
         4 . The method of  claim 3  wherein a wall of the catheter is positioned between the narrow proximal end of the body and the wall of the vessel as the proximal length of the body is drawn into the lumen of the catheter.  
     
     
         5 . The method of  claim 1  wherein a wall of the catheter urges the filter's body radially inwardly toward said radially reduced configuration as the body is drawn into the lumen thereof.  
     
     
         6 . The method of  claim 1  wherein the filter is urged along the channel in said radially reduced configuration within a deployment catheter.  
     
     
         7 . The method of  claim 6  wherein the same catheter is used as both the deployment catheter and the retrieval catheter.  
     
     
         8 . The method of  claim 6  wherein the deployment catheter's wall constrains the filter body in said radially reduced configuration when the body is received in the lumen thereof, body being radially expanded by deploying the filter out of the distal end of the catheter, whereupon the body resiliently expands radially outwardly upon removal of the constraint.  
     
     
         9 . The method of  claim 1  wherein the retrieval catheter is held substantially stationary as the proximal length of the filter's body is drawn therewithin.  
     
     
         10 . The method of  claim 1  wherein the proximal length of the filter's body is drawn into the catheter's lumen by holding the body substantially stationary and advancing the catheter distally over the proximal length thereof.  
     
     
         11 . The method of  claim 1  wherein the filter is carried by a mandrel, the catheter being advanced along the mandrel prior to drawing the body of the filter into the lumen thereof.  
     
     
         12 . A collapsible filter system comprising: 
 a) a mandrel having a distal end and a proximal end; and    b) a filter carried along the mandrel, the filter comprising a radially expandable body having a proximal end and a distal end, the body being formed of a porous, resilient fabric having pores therein through which a body fluid may pass, but which restrict passage therethrough of particulate material entrained in the body fluid;    c) a proximally oriented hole passing through the fabric along a proximal length of the filter's body, the hole being spaced distally of the proximal end of the body and being at least about ten times the size of said pores.    
     
     
         13 . The medical filter of  claim 12  wherein the proximal length of the body tapers toward the body's proximal end.  
     
     
         14 . The medical filter of  claim 12  wherein one of the proximal end and the distal end of the body is secured to the mandrel at a fixed location therealong while the other end of the body is slidably carried by the mandrel.  
     
     
         15 . The medical filter of  claim 12  wherein the proximal end of the body is secured to the mandrel at a fixed location therealong while the distal end of the body is slidably carried by the mandrel.  
     
     
         16 . The medical filter of  claim 12  wherein the mandrel includes a stop spaced proximally of its distal end and positioned between the proximal and distal ends of the body, a proximal length of the mandrel extending proximally of the stop and a distal length of the mandrel extending distally of the stop.  
     
     
         17 . The medical filter of  claim 16  wherein the proximal end of the body is slidably carried along the proximal length of the mandrel and the distal end of the body is slidably carried along the distal length of the mandrel, the proximal and distal ends being slidable along the mandrel independently of one another such that the distance between the proximal and distal ends can be varied to effect different configurations of the filter.  
     
     
         18 . The medical filter of  claim 12  wherein the proximal end of the body is affixed to the mandrel adjacent a distal end thereof.  
     
     
         19 . The medical filter of  claim 12  wherein the proximal length of the filter's body includes a plurality of proximally oriented holes through the fabric.  
     
     
         20 . The medical filter of  claim 12  wherein the filter body defines an enclosure for retaining particulate material therein, the mandrel extending through the enclosure.  
     
     
         21 . The medical filter of  claim 20  wherein the enclosure has a central axis, the mandrel being spaced radially outward from the central axis and extending closer to one side of the body than to an opposite side of the body.  
     
     
         22 . A method of using the medical filter of  claim 12  wherein the radially expandable body is placed in a radially reduced configuration for deployment; the body is radially expanded to an expanded configuration at a treatment site; and a retrieval sheath is urged distally with respect to the filter, the retrieval sheath receiving therewithin the proximal length of the filter's body while engaging a periphery of the body distally of the opening, thereby effectively closing the proximally oriented opening within the retrieval sheath.