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.

1 . A method of deploying a medical filter within a channel in a patient, the method comprising: 
 a) providing a filter having a radially expandable body having proximal and distal ends, the proximal end connected to a proximal element and the distal end connected to a distal element, the proximal and distal elements being ring shaped and sized to receive an elongate member in a configuration such that the proximal and distal elements are spaced apart along a longitudinal length of the elongate member, the filter defining an enclosure, the body having a distal length and a proximal length, the body being formed of a porous, resilient fabric comprising strands spaced apart to define pores extending through the fabric through which a body fluid may pass, but which restrict passage therethrough of particulate material entrained in the fluid, the body having at least one proximally oriented opening formed between strands of the fabric, the strands having been spaced apart such that the at least one opening is at least ten times the size of the pores, the at least one opening passing through the fabric along the proximal length of the body, 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 channel and the opening in the body is oriented proximally;    d) permitting 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 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 the 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 the 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 channel 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 channel 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 the 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 the 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 the radially reduced configuration when the body is received in the lumen thereof, the 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 . The method of  claim 1  wherein the elongate member is a guidewire.  
   
   
       13 . A method of making a medical filter body comprising: 
 providing a tubular metal braid having distal and proximal ends, the braid being formed from wire strands;    passing a forming mandrel between wire strands of the braid between the distal and proximal ends of the tubular braid to force the wire strands apart such that they extend about a periphery of the forming mandrel;    heating the tubular metal braid to a temperature sufficient to heat set the wire strands extended about the periphery of the forming mandrel such that an opening in the shape of the periphery of the forming mandrel is formed in the metal braid; and    removing the forming mandrel from the tubular braid.    
   
   
       14 . The method of  claim 13  wherein the distal and proximal ends of the tubular metal braid are tapered.  
   
   
       15 . The method of  claim 13  wherein the forming mandrel has an external molding surface and wherein the method further comprises applying axial tension to the braid to draw the braid down against the molding surface of the forming mandrel.  
   
   
       16 . The method of  claim 13  wherein the forming mandrel has an external molding surface with a diameter greater than a diameter of the tubular braid and wherein the method further comprises applying axial tension to the braid to draw the braid down against the molding surface of the forming mandrel.  
   
   
       17 . The method of  claim 13  wherein the forming mandrel has an external molding surface having a diameter greater than a diameter of the tubular braid and wherein during the step of passing the forming mandrel between wire strands of the braid the diameter of the braid increases.  
   
   
       18 . The method of  claim 17  further comprising: 
 applying axial tension to the braid to draw the braid down against the external molding surface of the forming mandrel.    
   
   
       19 . A method of making a medical filter comprising: 
 providing a tubular metal braid formed of wire strands;    attaching distal and proximal elements to the braid spaced from one another to form a filter body between the proximal and distal elements, the filter body having a proximal portion extending between the proximal element and a midpoint of the filter body;    passing a forming mandrel between wire strands of the proximal portion of the braid to force the wire strands to extend about a periphery of the forming mandrel;    heating the tubular metal braid to a temperature sufficient to heat set the wire strands extended about the periphery of the forming mandrel to form a proximal opening in the filter body; and    removing the forming mandrel.    
   
   
       20 . The method of  claim 19  wherein the forming mandrel has an external molding surface and wherein the method further comprises applying axial tension to the braid to draw the braid down against the external molding surface of the forming mandrel.  
   
   
       21 . The method of  claim 19  wherein the forming mandrel has an external molding surface with a diameter greater than a diameter of the tubular braid and wherein the method further comprises applying axial tension to the braid to draw the braid down against the external molding surface of the forming mandrel.  
   
   
       22 . The method of  claim 19  wherein the forming mandrel has an external molding surface having a diameter greater than a diameter of the tubular braid and wherein during the step of passing the forming mandrel between wire strands of the braid the diameter of the braid increases.  
   
   
       23 . The method of  claim 19  further comprising: 
 applying axial tension to the braid to draw the braid down against the forming mandrel.    
   
   
       24 . The method of  claim 19  further comprising: 
 trimming the braid at a distal end of the distal element and at a proximal end of the proximal element.    
   
   
       25 . The method of  claim 19  wherein the forming mandrel has an external molding surface with a periphery that generally coincides with a desired shape of the opening in the filter body.  
   
   
       26 . A method of making an opening in the tubular body of a medical filter formed from braided wire strands, the tubular body having distal and proximal ends, the method comprising: 
 passing a forming mandrel between wire strands of the braid between the distal and proximal ends of the tubular body to force the wire strands apart such that they extend about a periphery of the forming mandrel;    heating the tubular body to a temperature sufficient to heat set the wire strands extended about the periphery of the forming mandrel such that an opening in the shape of the periphery of the forming mandrel is formed in the tubular body of the medical filter; and    removing the forming mandrel from the tubular body.    
   
   
       27 . Apparatus for filtering emboli from blood flowing through a vessel, the apparatus comprising: 
 a guide wire having a distal region and a stop on the distal region;    a capture ring disposed for translation on the guide wire, the stop limiting translation of the capture ring in a distal direction; and    a filter sac connected to the capture ring.    
   
   
       28 . The apparatus of  claim 27  wherein, when the filter sac is deployed in the vessel, rotation or distal translation of the guide wire relative to the capture ring does not displace the filter sac, but retraction of the guide wire in a proximal direction causes the stop to abut against the capture ring.  
   
   
       29 . Apparatus for filtering emboli from blood flowing through a vessel, the apparatus comprising: 
 a guide wire having a first portion having a first diameter and a distal region having a second diameter greater than the first diameter; and    a filter element having a capture ring disposed for translation on the first portion, the capture ring having an aperture greater than the first diameter but smaller than the second diameter,    wherein rotation or distal translation of the guide wire relative to the capture ring does not displace the filter element.    
   
   
       30 . The apparatus of  claim 29  wherein the filter element comprises an expandable sac.  
   
   
       31 . The apparatus of  claim 29  wherein the guide wire further comprises a flange disposed on the distal region having a diameter larger than the diameter of the aperture in the capture ring.  
   
   
       32 . The apparatus of  claim 29  wherein the filter element has a contracted state suitable for transluminal delivery, and the distal region has a length that is greater than a length of the filter element in the contracted state.  
   
   
       33 . Apparatus for filtering emboli during treatment of occlusive disease in a vessel, the apparatus comprising: 
 a guide wire having a first diameter and a distal region having a second diameter greater than the first diameter;    a filter element having a sac coupled to a capture ring, the capture ring having an aperture greater than the first diameter but smaller than the second diameter,    wherein the filter element is disposed on the guide wire and the guide wire extends through the aperture with the distal region disposed distally of the capture ring, so that when the filter element is deployed in the vessel, rotation or distal translation of the guide wire does not displace the filter element, but retraction of the guide wire in a proximal direction causes the distal region to abut against the capture ring.    
   
   
       34 . A method of filtering emboli from blood flowing through a vessel, the method comprising: 
 providing a guide wire having a distal region including a stop, and a filter element having a capture ring disposed for translation on the guide wire proximal of the stop;    transluminally inserting the guide wire and filter element into a vessel;    deploying the filter element to engage a wall of the vessel, the filter element filtering emboli out of blood flowing through the vessel; and    advancing a treatment device along the guide wire to treat a portion of the vessel proximal to the location of the filter element, rotation or distal translation of the guide wire relative to the filter element imparted by the treatment device not displacing the filter element.    
   
   
       35 . The method of  claim 34  further comprising a step of, after use of the treatment device is completed, pulling the guide wire proximally so that the stop engages the capture ring and causes the filter element to return to the contracted state.  
   
   
       36 . The method of  claim 34  further comprising: 
 providing a delivery sheath; and    compressing the filter element to a contracted state to insert the filter element within the delivery sheath.    
   
   
       37 . The method of  claim 34  wherein the filter element comprises an expandable sac, and deploying the filter element comprises expanding the expandable sac so that a perimeter of the expandable sac contacts the wall of the vessel.  
   
   
       38 . The method of  claim 37  wherein the filter element further comprises a cylindrical sleeve and deploying the filter element further comprises expanding the cylindrical sleeve against the wall of the vessel.  
   
   
       39 . The method of  claim 34  further comprising providing a catheter having a lumen, and pulling the guide wire proximally causes the filter element to become retracted within the lumen.  
   
   
       40 . Apparatus for filtering emboli from blood flowing through a vessel, the apparatus comprising: 
 a mandrel having a distal end and a stop spaced proximally of the distal end;    a slider disposed for translation on the mandrel, the stop limiting translation of the slider in a distal direction; and    a vascular filter connected to the slider.    
   
   
       41 . The apparatus of  claim 40  wherein, when the vascular filter is deployed in the vessel, rotation or distal translation of the mandrel relative to the slider does not displace the vascular filter, but retraction of the mandrel in a proximal direction causes the stop to abut against the slider.  
   
   
       42 . Apparatus for filtering emboli from blood flowing through a vessel, the apparatus comprising: 
 a mandrel having a distal end and a proximal length having a first diameter and a stop spaced proximally of the distal end having a second diameter greater than the first diameter; and    a filter element having a slider disposed for translation on the proximal length, the slider having an aperture greater than the first diameter but smaller than the second diameter,    wherein rotation or distal translation of the mandrel relative to the slider does not displace the filter element.    
   
   
       43 . The apparatus of  claim 42  wherein the filter element comprises an expandable vascular filter.  
   
   
       44 . Apparatus for filtering emboli during treatment of occlusive disease in a vessel, the apparatus comprising: 
 a mandrel having a distal end and a proximal length having a first diameter and a stop spaced proximally of the distal end, the stop having a second diameter greater than the first diameter;    a filter element having a vascular filter coupled to a slider, the slider having an aperture greater than the first diameter but smaller than the second diameter,    wherein the filter element is disposed on the mandrel and the mandrel extends through the aperture with the stop disposed distally of the slider, so that when the filter element is deployed in the vessel, rotation or distal translation of the mandrel does not displace the filter element, but retraction of the mandrel in a proximal direction causes the stop to abut against the slider.    
   
   
       45 . A method of filtering emboli from blood flowing through a vessel, the method comprising: 
 providing a mandrel having a distal region including a stop, and a filter element having a slider disposed for translation on the mandrel proximal of the stop;    transluminally inserting the mandrel and filter element into a vessel;    deploying the filter element to engage a wall of the vessel, the filter element filtering emboli out of blood flowing through the vessel; and    advancing a treatment device along the mandrel to treat a portion of the vessel proximal to the location of the filter element, rotation or distal translation of the mandrel relative to the filter element imparted by the treatment device not displacing the filter element.    
   
   
       46 . The method of  claim 45  further comprising a step of, after use of the treatment device is completed, pulling the mandrel proximally so that the stop engages the slider and causes the filter element to return to the contracted state.  
   
   
       47 . The method of  claim 45  further comprising: 
 providing a catheter having a lumen; and    compressing the filter element to a contracted state to insert the filter element within the lumen of the catheter.    
   
   
       48 . The method of  claim 45  wherein the filter element comprises an expandable vascular filter, and deploying the filter element comprises expanding the expandable vascular filter so that a perimeter of the expandable vascular filter contacts the wall of the vessel.  
   
   
       49 . The method of  claim 45  further comprising providing a catheter having a lumen, and pulling the mandrel proximally causes the filter element to become retracted within the lumen.