SUPERELASTIC MEDICAL INSTRUMENT
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.
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.