Tissue resection snares

Abstract

A tissue resection device for resecting tissue from a target site within a patient's body. The device includes an elongate shaft having a proximal end and a distal end. An actuation member extends partially through the shaft, and reciprocates within the shaft between a retracted position and an extended position. Multiple snare wires extend through the actuation member, and emerge outwards from a distal portion of the actuation member. The snare wires cooperate and join to form a snare loop, which engages the tissue intended to be resected. The snare loop is configured to enhance friction while engaging the tissue, to resect the tissue.

What is claimed is: 
     
         1 . A tissue resection device comprising:
 an elongate shaft having a proximal end and a distal end;   an actuation member extending at least partially through the elongate shaft, and being configured to reciprocate within the shaft between a retracted position and an extended position;   one or more snare wires extending through a lumen of the actuation member and emerging outwards from a distal portion of the actuation member; and   a snare loop formed by the one or more snare wires, the snare loop being configured to engage tissue intended to be resected from a target site, and further comprising a plurality of elements positioned over a peripheral surface of the snare loop, the elements being configured to increase friction between the tissue and the snare loop.   
     
     
         2 . The tissue resection device of  claim 1 , wherein reciprocation of the actuation member moves the snare loop between an expanded orientation and a retracted position within the elongate shaft, and wherein, in the extended position of the actuation member, the snare loop is in the expanded orientation, and in the retracted position of the actuation member, the snare loop retracts into the elongate shaft. 
     
     
         3 . The tissue resection device of  claim 1 , wherein the one or more snare wires have a flattened, rectangular cross-section, and a portion of each of the snare wires is anchored to an interior portion of the actuation member, wherein the interior portion of the actuation member includes a surface corresponding to the cross-section of the one or more snare wires to maintain the orientation of the snare wires with respect to the tissue. 
     
     
         4 . A tissue resection device of  claim 1 , wherein the snare loop has one of a plurality of grooves, striations, indentations, protrusions, and depressions provided over a peripheral portion thereof, the grooves, the striations, the indentations, the protrusions, or the depressions extending at least partially over the length of the snare loop, to enhance friction during engagement of the snare loop with the tissue. 
     
     
         5 . A tissue resection device of  claim 1 , wherein the snare loop has an irregular rough surface, configured to enhance its engagement with the tissue. 
     
     
         6 . A tissue resection device of  claim 2 , wherein, in the expanded orientation, the snare loop has one of an elliptical, a circular, an ovular, a square, a rectangular, a polygonal and an irregular shape, overlaying the tissue. 
     
     
         7 . A tissue resection device of  claim 1 , wherein in the expanded orientation of the snare loop, the snare wires orient substantially perpendicular to a plane containing the tissue, and a distal portion of each of the snare wires is anchored to an interior portion of the actuation member. 
     
     
         8 . A tissue resection device of  claim 7 , wherein each of the plurality of elements is a traction ring engaging and at least partially enclosing the snare loop's cross-sectional surface, and having an irregular surface configured to engage the tissue, the irregular surface being configured to increase friction between the snare loop and the tissue, for resection of the tissue. 
     
     
         9 . A tissue resection device of  claim 8 , wherein each of the traction rings is a C-shaped ring having an open-ended structure. 
     
     
         10 . A tissue resection device of  claim 8 , wherein the traction rings are one of snap-fitted, press-fitted and crimped to the snare loop, and have a slanting and decreasing cross-sectional rear structure, to facilitate smooth retraction of the snare loop into the actuation member. 
     
     
         11 . A tissue resection device of  claim 1 , further comprising, a substantially helical structure extending across and coiled around the snare loop, the helical structure having its extreme ends anchored to the distal end of the elongate shaft, and being configured to grasp portions of the tissue between the turns thereof. 
     
     
         12 . A tissue resection device of  claim 11 , wherein the adjacent turns of the helical structure are movable with respect to each other, to alter the pitch of the helical structure in response to a transition of the snare loop between an expanded orientation and a retracted position within the elongate shaft. 
     
     
         13 . A tissue resection device of  claim 12 , further comprising an actuation element coupled to the helical structure, the actuation element being configured to independently reduce the spacing between the adjacent turns of the helical structure, to facilitate grasping of the portions of the tissue between the adjacent turns. 
     
     
         14 . The tissue resection device of  claim 1 , further comprising an auxiliary loop provided at a peripheral portion of the snare loop, the auxiliary loop being configured to engage and resect a portion of the tissue intended to be resected, and being further configured to increase frictional engagement of the snare loop with the tissue, 
     
     
         15 . The tissue resection device of  claim 14 , wherein the auxiliary loop is provided at a distal peripheral portion of the snare loop, and is configured to engage the tissue independent of the engagement of the snare loop with the tissue. 
     
     
         16 . A tissue resection device comprising:
 an elongate shaft having a proximal end and a distal end;   an actuation member extending at least partially through the elongate shaft, and being configured to reciprocate within the shaft between a retracted position and an extended position; and   one or more snare wires extending through a lumen of the actuation member, emerging out from a distal portion of the actuation member, and having a flattened, rectangular cross-section, such that the snare wires orient substantially perpendicular o a plane containing tissue to be resected;   wherein the interior portion of the actuation member includes a surface corresponding to the cross-section of the one or more snare wires to maintain the orientation of the snare wires with respect to the tissue.   
     
     
         17 . The tissue resection device of  claim 1 , wherein reciprocation of the actuation member moves the snare wires between an expanded orientation and a retracted position within the elongate shaft, and wherein, in the extended position of the actuation member, the snare wires are in the expanded orientation, and in the retracted position of the actuation member, the snare wires retract into the elongate shaft. 
     
     
         18 . A tissue resection device of  claim 1 , wherein the snare wires have one of a plurality of grooves, striations, indentations, protrusions, and depression provided over a peripheral portion thereof, the grooves, the striations, the indentations, the protrusions, or the depressions, extending at least partially over the length of the snare loop, to enhance friction during engagement of the snare wires with the tissue. 
     
     
         19 . A tissue resection device comprising:
 an elongate shaft having a proximal end and a distal end;   an actuation member extending at least partially through the elongate shaft, and being configured to reciprocate within the shaft between a retracted position and an extended position; and   a snare loop formed by one or more snare wires extending through a lumen of the actuation member, the snare loop being configured to engage tissue intended to be resected from a target site,   wherein the snare loop includes a plurality of pinching structures positioned around different peripheral positions of the snare loop, configured to engage the tissue at locations of the pinching structures.   
     
     
         20 . The tissue resection device of  claim 19 , wherein the snare loop includes one or more snare wires having a flattened, rectangular cross-section, and a portion of each of the snare wires is anchored to an interior portion of the actuation member, wherein the interior portion of the actuation member includes a surface corresponding to the cross-section of the one or more snare wires to maintain the orientation of the snare wires with respect to the tissue.