Medical Retrieval Devices

Abstract

A medical retrieval device may include an elongated member having first and second end portions and a middle portion. The elongated member may be configured such that the first and second end portions are proximal one another and extend substantially parallel to one another along a longitudinal axis. The middle portion may have an unconstrained basket configuration. A first sheath may be configured to receive at least a portion of the first end portion, and a second sheath may be configured to receive at least a portion of the second end portion. At least one of the first and second sheaths may be movable relative to the middle portion so as to constrain the middle portion in an elongated configuration.

1 . A medical retrieval device, comprising:
 an elongated member having a middle region defining, in an unconstrained state, a basket configured to capture a kidney stone or a fragment thereof, the middle region located between side-by-side first and second end regions extending parallel to a longitudinal axis;   a sheath substantially surrounding the elongated member in a constrained state, at least a portion of the middle region having a transverse dimension substantially similar to or less than a transverse dimension of the sheath; and   a handle including an actuation mechanism connected separately to a proximal end of the sheath and a proximal end of the elongated member, the actuation mechanism enabling simultaneous translation of the sheath in a first direction and the elongated member in a second direction opposite of the first direction.   
     
     
         2 . The device according to  claim 1 , wherein the sheath constrains the middle region into a substantially elongated configuration in the constrained state. 
     
     
         3 . The device according to  claim 1 , wherein the actuation mechanism includes a slide mechanism coupled to a belt, and wherein the proximal end of the sheath and the proximal end of the elongated member are coupled to the belt. 
     
     
         4 . The device according to  claim 3 , wherein the proximal end of the sheath and the proximal end of the elongated member are fixed to respective first and second anchors fixed to the belt. 
     
     
         5 . The device according to  claim 1 , wherein the actuation mechanism enables distal advancement of the elongate member at a first rate greater than a second rate of proximal withdrawal of the sheath. 
     
     
         6 . The device according to  claim 1 , wherein the elongated member comprises a refractory metal wire wrapped around a shape memory metal wire along at least the middle region. 
     
     
         7 . The device according to  claim 6 , wherein the refractory metal is tungsten and the shape memory metal is nitinol. 
     
     
         8 . The device according to  claim 1 , wherein the first and second end regions are joined, respectively, to first and second proximal extension members extending in parallel relation to the proximal end of the elongated member. 
     
     
         9 . The device according to  claim 8 , wherein the elongated member comprises a refractory metal wire wrapped around a shape memory metal wire from the first end region to the second end region. 
     
     
         10 . The device according to  claim 9 , wherein the refractory metal is constructed of tungsten, wherein the shape memory metal is constructed of nitinol, and wherein the first and second proximal extension members are constructed of a material other than nitinol. 
     
     
         11 . The device according to  claim 10 , wherein the first and second proximal extension members are constructed of stainless steel. 
     
     
         12 . The device according to  claim 1 , wherein the basket forms a spiral shape. 
     
     
         13 . The device according to  claim 12 , wherein the basket lies along a plane perpendicular to the longitudinal axis. 
     
     
         14 . The device according to  claim 1 , wherein the sheath comprises polytetrafluoroethylene (PTFE).