Superelastic medical instrument

Abstract

Certain aspects relate to a superelastic medical instrument that of bending elastically through the tortuous pathways of an endoscope, returning to a straight shape upon deployment from the endoscope, and deploying straight along the axis of the end of the bronchoscope (within a tolerated margin) to distances of 2 cm or more.

What is claimed is: 
     
         1 . A biopsy needle assembly, comprising:
 a needle formed from a superelastic alloy, the needle including:
 a body portion extending from a distal end of the needle to a proximal end of the needle, and 
 an inner surface of the needle forming a lumen extending through at least a portion of the body portion to an opening in the distal end, wherein the lumen and the opening are configured to acquire a tissue biopsy; 
   an elongate member attached at the proximal end of the needle; and   a tubular jacket including an interior channel, wherein:
 in a first configuration, the distal end of the needle is positioned within the interior channel, and 
 in a second configuration, in response to distal movement of the elongate member through the interior channel, the distal end of the needle is extended beyond a distal end of the tubular jacket. 
   
     
     
         2 . The assembly of  claim 1 , wherein the superelastic alloy comprises Nitinol. 
     
     
         3 . The assembly of  claim 1 , wherein the needle has a wall thickness of approximately 0.0015 inches thick. 
     
     
         4 . The assembly of  claim 1 , further comprising:
 a sharpened tip at the distal end of the needle; and   a radiopaque material positioned around the needle near the sharpened tip.   
     
     
         5 . The assembly of  claim 4 , wherein the radiopaque material has a thickness of at least 200 microinches. 
     
     
         6 . The assembly of  claim 1 , wherein the elongate member comprises a polymer tube reflowed around an overlap region located at the proximal end of the needle. 
     
     
         7 . The assembly of  claim 6 , wherein the polymer tube comprises a conical section at its distal end prior to or after being reflowed around the overlap region. 
     
     
         8 . The assembly of  claim 6 , wherein the needle has a length of approximately 5 centimeters from the distal end to the proximal end, and wherein the overlap region has a length of approximately 2 centimeters. 
     
     
         9 . The assembly of  claim 6 , wherein the needle has a length of approximately 4 centimeters from the distal end to the proximal end, and wherein the overlap region has a length of approximately 1 centimeters. 
     
     
         10 . The assembly of  claim 6 , wherein the needle has a length between 1 centimeter and 6 centimeters. 
     
     
         11 . The assembly of  claim 6 , wherein the overlap region has a length of 0.5 cm to 3 cm. 
     
     
         12 . The assembly of  claim 6 , wherein a channel formed by an interior surface of the polymer tube is in fluid communication with the lumen to provide pressure through the opening. 
     
     
         13 . The assembly of  claim 6 , further comprising a plurality of surface features formed on the needle at the overlap region, wherein the polymer tube is reflowed around the surface features. 
     
     
         14 . The assembly of  claim 13 , wherein the plurality of surface features comprise a grit blasted exterior surface of the needle. 
     
     
         15 . The assembly of  claim 13 , wherein the plurality of surface features comprise laser cut holes each extending through a wall of the needle. 
     
     
         16 . The assembly of  claim 6 , wherein the overlap region is located at a distal end of the tube, and wherein the proximal end of the needle includes a first spiral channel or cut, and the distal end of the tube includes a second spiral channel or cut structured to mechanically mate with the first spiral channel or cut. 
     
     
         17 . The assembly of  claim 6 , wherein the overlap region is located at a distal end of the tube, and wherein the proximal end of the needle and the distal end of the tube are secured at the overlap region by a flexible adhesive. 
     
     
         18 . The assembly of  claim 6 , wherein the overlap region is located at a distal end of the tube, and wherein the proximal end of the needle and the distal end of the tube are secured at the overlap region by screws. 
     
     
         19 . The assembly of  claim 1 , wherein the superelastic alloy, in its martensite phase, deforms reversibly up to 10% from the original shape. 
     
     
         20 . A method of obtaining a tissue biopsy, the method comprising:
 positioning a distal end of a working channel of an endoscope adjacent to a desired biopsy site;   advancing a tubular jacket through the working channel, the jacket including a biopsy needle assembly positioned within the jacket, the biopsy needle assembly comprising:
 a needle formed from a superelastic alloy, the needle including:
 a body portion extending from a distal end of the needle to a proximal end of the needle, and 
 an inner surface of the needle forming a lumen extending through at least a portion of the body portion to an opening in the distal end, wherein the lumen and the opening are configured to acquire a tissue biopsy; and 
 
 an elongate member attached at the proximal end of the needle; 
   actuating a first linear motion of a proximal end the elongate member to drive extension of at least a portion of the needle out of the jacket into the biopsy site;   acquiring a tissue sample from the biopsy site through the opening of the needle; and   actuating a second linear motion of the proximal end the elongate member to drive retraction of the needle out of the biopsy site.