Method of forming medical devices; intravascular occlusion devices

Abstract

The present invention provides a method of forming a medical device and medical devices which can be formed in accordance with the method. In one embodiment, the method includes the steps of a) providing a metal fabric formed of a plurality of strands formed of a metal which can be heat treated to substantially set a desired shape; b) deforming the metal fabric to generally conform to a surface of a molding element; c) heat treating the metal fabric in contact with the surface of the molding element to substantially set the shape of the fabric in its deformed state; and d) removing the metal fabric from contact with the molding element. The resulting metal fabric will define a medical device which can be collapsed for passage through a catheter or the like for deployment in a channel of a patient's body. Medical devices made in accordance with this method can have varying structures. In one embodiment, the medical device is carried by a guidewire and has a metal fabric extending between first and second ends, the ends of the device being adapted to slide along the guidewire. The metal fabric has a collapsed configuration min which the ends of the metal fabric are spaced from one another along the guidewire and a preset expanded configuration in which the ends of the metal fabric are positioned closer to one another. The metal fabric will cause the device to elastically substantially resume its preset expanded configuration when released from confinement within a channel in a patient's body.

What is claimed is:  
     
         1 . A trap for trapping particulate material entrained in a fluid within a channel of a patient's body, comprising a guidewire having a distal end and a basket carried by the guidewire adjacent said distal end; the basket being adapted to strain the particulate material from fluid passing therethrough and comprising a metal fabric having first and second ends, at least one end of the fabric being adapted to slide along the guidewire; the metal fabric having a collapsed configuration wherein the first and second ends are spaced from one another a first distance along the guidewire and the metal fabric has a first diameter, and an expanded configuration wherein the first and second ends are spaced a second, shorter distance along the guidewire and the metal fabric has a second diameter, the first diameter being less than the second diameter.  
     
     
         2 . A trap for trapping particulate material entrained in a fluid within a channel of a patient's body, comprising a guidewire having a distal segment and a metal fabric, the metal fabric having a first end carried by the distal segment and a second end slidable along the guidewire, the metal fabric being disposed adjacent the outer surface of the guidewire when the second end is spaced proximally of the first end and extending generally outwardly of the guidewire when the second end is slid nearer the first end to define a particle-trapping screen.  
     
     
         3 . The trap of  claim 2  wherein the first end is affixed to the guidewire.  
     
     
         4 . The trap of  claim 2  wherein the metal fabric is resilient and the second end will resiliently slide toward the first end to define the particle trapping screen when the fabric is not constrained.  
     
     
         5 . The trap of  claim 2  wherein a first length of the metal fabric extending proximally from the first end defines a distal surface of the screen and a second length of the metal fabric extending distally from the second end of the fabric defines a proximal surface of the screen.  
     
     
         6 . The trap of  claim 5  wherein the screen is generally dome-shaped and the second length of the fabric is received within the first length of the fabric.  
     
     
         7 . The trap of claim S wherein a central portion of the metal fabric defines a proximally-facing lip of the screen.  
     
     
         8 . The trap of  claim 2  further comprising a tether extending from said screen to the guidewire, the tether being attached at one end to the guidewire.  
     
     
         9 . The trap of  claim 8  wherein the screen has a periphery, the tether comprising a wire attached at each end to the guidewire and extending about the periphery of the screen such that when the tether is drawn inwardly toward the guidewire it will act as a drawstring to collapse the periphery of the screen toward the guidewire.  
     
     
         10 . The trap of  claim 2  further comprising a cover formed of a metal fabric, the cover being slidable along the guidewire from a first position spaced proximally of the screen toward a second position adjacent the screen.  
     
     
         11 . The trap of  claim 10  wherein the cover has two ends, the cover being disposed adjacent the outer surface of the guidewire when one end is spaced proximally of the other end and extending generally outwardly of the guidewire to a diameter at least as great as an outer diameter of the screen when one end of the cover is slid nearer the other end.  
     
     
         12 . The trap of  claim 10  wherein the screen is generally dome-shaped and includes a proximally-facing lip, the cover in an expanded configuration defining a recess sized to receive the lip of the screen.  
     
     
         13 . The trap of  claim 12  wherein the screen has an outer diameter and the cover has an inner diameter greater than the outer diameter of the screen.  
     
     
         14 . A method of trapping particulate material entrained in a fluid within a channel of a patient's body, comprising: 
 a) providing a metal fabric having a collapsed configuration wherein it has a first diameter and an expanded configuration wherein it has a second, greater diameter and defines a proximally-facing particle-receiving cavity;    b) collapsing the metal fabric into its collapsed configuration and urging the metal fabric along said channel to a deployment site;    c) permitting the metal fabric to resiliently substantially return to its expanded configuration;    d) allowing the fluid to flow through the metal fabric to trap a portion of the particulate material in the cavity;    e) at least partially closing the metal fabric to retain the trapped particulate material is retained within a closed cavity; and    f) retracting the metal fabric along the channel with the particulate material retained within the collapsed cavity.    
     
     
         15 . The method of  claim 14  wherein the metal fabric in its collapsed configuration is urged along a catheter positioned within a lumen of the channel.  
     
     
         16 . The method of  claim 15  wherein the fabric is allowed to substantially return to its expanded configuration by urging the fabric beyond the distal end of the catheter.  
     
     
         17 . The method of  claim 14  wherein the metal fabric is closed by urging a cover into engagement with a distal portion of the metal fabric to retain the particulate material within the cavity.  
     
     
         18 . The method of  claim 17  wherein the cover has an expanded configuration, further comprising the steps of collapsing the cover, urging the cover along the channel to a position spaced proximally of the metal fabric, and allowing the cover to resiliently substantially return to its expanded configuration prior to urging the cover into engagement with the metal fabric.  
     
     
         19 . The method of  claim 14  wherein the metal fabric is carried by a guidewire and at least one tether extends from a proximally-facing lip of the fabric proximally to the guidewire, wherein the metal fabric is closed by urging the tether down toward the guidewire to draw the lip of the metal fabric toward the guidewire.  
     
     
         20 . The method of  claim 19  wherein the tether is urged toward the guidewire by urging a sheath distally along the guidewire toward the metal fabric, the sheath having an lumen smaller than the lip of the metal fabric.  
     
     
         21 . A method of forming a medical device comprising the steps of: 
 a) providing a metal fabric formed of a plurality of strands, the strands being formed of a metal which can be heat treated to substantially set a desired shape;    b) deforming the metal fabric to generally conform to a surface of a molding element;    c) heat treating the metal fabric in contact with the surface of the molding element at an elevated temperature, the temperature and the duration of the heat treatment being sufficient to substantially set the shape of the fabric in its deformed state; and    d) removing the metal fabric from contact with the molding element, whereby the metal fabric defines a medical device which can be collapsed for passage through a catheter for deployment in a channel of a patient's body.    
     
     
         22 . A medical device made in accordance with the method of  claim 21 .  
     
     
         23 . Method of treating a physiological condition comprising the steps of: 
 a) providing a medical device made substantially in accordance with the to method of  claim 1;     b) positioning a catheter within a channel in a patient's body to position a distal end of the catheter adjacent a desired treatment site;    c) collapsing the medical device and inserting the device into the catheter's lumen;    d) urging the device along the lumen of the catheter and out of the distal end of the catheter for deployment at the treatment site.    
     
     
         24 . A method of forming a medical device for deployment in a channel in a patient's body, the device having a preset expanded configuration and a collapsed configuration enabling passage of the device through a catheter, comprising the steps of: 
 a) providing a metal fabric formed of a plurality of strands having a first relative orientation with respect to one another, the strands being formed of a metal which can be heat treated to substantially set a desired shape;    b) generally conforming the metal fabric to a surface of a molding element to substantially define the device's expanded configuration, thereby reorienting the relative positions of the strands with respect to one another;    c) treating the metal fabric while conformed to the surface of the molding element to substantially set the strands in their reoriented relative positions; and    d) removing the metal fabric from the molding element, whereby the metal fabric defines a medical device which can be deformed into its collapsed configuration for passage through a catheter for deployment in a channel of a patient's body, and which substantially resumes its preset expanded configuration in such channel.    
     
     
         25 . A collapsible medical device comprising a metal fabric having a collapsed configuration for delivery through a channel in a patient's body and a generally dumbbell-shaped expanded configuration for substantially filling a lumen of the channel, the metal fabric in its expanded configuration having two expanded diameter portions and a reduced diameter portion disposed between the two expanded diameter portions.