Snare with loop made of heat shrinkable shape memory material and method of use thereof

Abstract

A tissue snare comprises an elongated member having a distal end and a loop formed of a shape memory material, the loop including a tissue receiving interior opening and being connected to the distal end of the elongated member, properties of the shape memory material being selected so that, when a temperature of the loop exceeds a critical temperature thereof, the loop constricts from an expanded state to a constricted state. A method of treating tissue comprises placing a loop of a snare around a portion of tissue to be treated while the loop is in an expanded configuration, the loop being formed of a shape memory material having a critical temperature so that, when a temperature of the loop is above the critical temperature, the loop transitions from the expanded configuration to a constricted configuration in combination with transitioning, after the loop has been placed around the portion of tissue to be treated, the loop from the expanded configuration to the constricted configuration to tighten the loop around the portion of tissue to be treated.

1 . A tissue snare comprising: 
 an elongated member having a distal end; and    a loop comprising a shape memory material, the loop including a tissue receiving interior opening and being connected to the distal end of the elongated member, properties of the shape memory material being selected so that, when a temperature of the loop exceeds a critical temperature thereof, the loop constricts from an expanded state to a constricted state.    
   
   
       2 . The snare according to  claim 1 , wherein the shape memory material is a shape memory polymer.  
   
   
       3 . The snare according to  claim 1 , wherein the shape memory material is a shape memory metal.  
   
   
       4 . The snare according to  claim 1 , further comprising a temperature control apparatus controlling a temperature of the loop to control transitions of the loop between the expanded state and the constricted state.  
   
   
       5 . The snare according to  claim 4 , wherein the temperature control mechanism includes a fluid lumen extending to the distal end of the elongated member to provide one of cooling and heating fluid to the loop.  
   
   
       6 . The snare according to  claim 5 , wherein the temperature control mechanism further comprises a fluid conduit extending along at least a portion of the length of the loop.  
   
   
       7 . The snare according to  claim 6 , wherein the fluid conduit extends from a distal opening of the fluid lumen, within the loop.  
   
   
       8 . The snare according to  claim 5 , further comprising a fluid dispensing opening located adjacent to the distal end of the elongated member for directing fluid from the fluid lumen, toward an exterior surface of the loop.  
   
   
       9 . The snare according to  claim 4 , wherein the temperature control mechanism further comprises a heating element positioned along at least a portion of the length of the loop.  
   
   
       10 . The snare according to  claim 3 , wherein the heating element is integrally formed with the loop.  
   
   
       11 . The snare according to  claim 2 , wherein the heating element is bonded to an exterior surface of the loop.  
   
   
       12 . The snare according to  claim 1 , wherein the shape memory material is selected so that the critical temperature is greater than an ambient temperature to which the distal end will be exposed when in an operative position.  
   
   
       13 . The snare according to  claim 1 , wherein the loop includes a first section extending along a curve from a distal end of the elongated member to a first section distal end separated from the distal end of the elongated member and a second section extending along a substantially straight line between the distal end of the elongated member and the first section distal end.  
   
   
       14 . A method of treating tissue comprising: 
 placing a loop of a snare around a portion of tissue to be treated while the loop is in an expanded configuration, the loop being formed of a shape memory material having a critical temperature so that, when a temperature of the loop is above the critical temperature, the loop transitions from the expanded configuration to a constricted configuration; and    after the loop has been placed around the portion of tissue to be treated, transitioning the loop from the expanded configuration to the constricted configuration to tighten the loop around the portion of tissue to be treated.    
   
   
       15 . The method according to  claim 14 , wherein the loop is transitioned from the expanded configuration to the constricted configuration by applying heat to the loop to raise the temperature thereof above the critical temperature.  
   
   
       16 . The method according to  claim 14 , wherein the critical temperature is selected to be lower than an ambient temperature in an environment in which the loop is to be used and wherein the loop is transitioned from the expanded configuration to the constricted configuration by exposure to body heat.  
   
   
       17 . The method according to  claim 16 , wherein the loop is maintained in the expanded configuration until a desired transition time by cooling the loop to maintain a temperature thereof below the critical temperature.  
   
   
       18 . The method according to  claim 17 , wherein the loop is connected to a proximal control handle via an elongated member and wherein heat is applied to the loop by supplying a heated fluid to the loop via a fluid conduit extending along the elongated member.  
   
   
       19 . The method according to  claim 18 , wherein the loop includes a fluid lumen extending therethrough, the fluid lumen receiving heated fluid from the fluid conduit.  
   
   
       20 . The method according to  claim 15 , wherein the loop is heated by an electric heating element.  
   
   
       21 . The method according to  claim 14 , wherein the constricted configuration is controlled to resect tissue received within the loop.  
   
   
       22 . The method according to  claim 14 , wherein the constricted configuration is controlled to cut off blood supply to tissue received within the loop.