Tissue welding and cutting apparatus and methods

Abstract

A surgical apparatus and methods for severing and welding tissue, in particular blood vessels. The apparatus includes an elongated shaft having a pair of relatively movable jaws at a distal end thereof. A first heating element on one of the jaws is adapted to heat up to a first temperature and form a welded region within the tissue, while a second heating element on one of the jaws is adapted to heat up to a second temperature and sever the tissue within the welded region. The first and second heating elements may be provided on the same or opposite jaws. A control handle provided on the proximal end of the elongated shaft includes controls for opening and closing the jaws, and may include an actuator for sending current through the first and second heating elements. The first and second heating elements may be electrically connected in series, and the first heating element may be bifurcated such that it conducts about one half of the current as the second heating element. A force-limiting mechanism provided either within the control handle, in the elongated shaft, or at the jaws limits the pressure applied to the tissue by the jaws to ensure that the tissue is severed and the ends effectively welded within a short amount of time.

1 . A surgical apparatus for welding and severing tissue, comprising:
 first and second relatively movable elongated jaws having jaw-facing surfaces;   an elongated shaft having the first and second relatively movable jaws attached to a distal end thereof;   a first heating element for welding tissue provided on the jaw-facing surface of the first jaw, the first heating element being adapted to heat up to a first temperature upon application of power; and   a second heating element for severing tissue also provided on the jaw-facing surface of the first jaw, the second heating element being adapted to heat up to a second temperature greater than the first temperature upon application of power.   
     
     
         2 . The apparatus of  claim 1 , wherein the first heating element has a lower electrical resistance than the second heating element. 
     
     
         3 . The apparatus of  claim 1 , wherein the first heating element has a wider profile than the second heating element in a plane transverse to the direction of elongation of the first jaw. 
     
     
         4 . The apparatus of  claim 1 , wherein the first heating element has a lower profile relative to the second heating element in a direction toward the second jaw. 
     
     
         5 . The apparatus of  claim 1 , wherein the second heating element extends generally centrally along the jaw-facing surface of the first jaw, and wherein the first heating element comprises at least two welding members, one each on either side of the second heating element. 
     
     
         6 . The apparatus of  claim 5 , wherein the at least two welding members are formed by a bifurcated segment of a one-piece heating element, the separated portions in the bifurcated segment being connected in parallel to a source of power. 
     
     
         7 . The apparatus of  claim 6 , wherein the first and second heating elements are connected in series to a common source of power such that a current passing through one of the pair of welding members is about one half the current passing through the second heating element. 
     
     
         8 . The apparatus of  claim 5 , wherein each of the welding members comprises a strip of material having a generally flat jaw-facing surface defining a lateral width, and wherein the second heating element defines a cylindrical jaw-facing surface having a lateral width smaller than that of either of the welding members. 
     
     
         9 . The apparatus of  claim 1 , wherein the second jaw includes no heating elements such that the first jaw is a “hot” jaw, and the second jaw is a “cold” jaw. 
     
     
         10 . The apparatus of  claim 1 , further including a third heating element for welding tissue also provided on the jaw-facing surface of the first jaw, the third heating element being adapted to heat up to a temperature upon application of power that is lower than the second temperature. 
     
     
         11 . The apparatus of  claim 1 , further including a control handle connected to a proximal end of the elongated shaft and a control actuator mounted on the handle for alternately separating and bringing together the jaw-facing surfaces of the elongated jaws, and a force-limiting interface between the control actuator and the elongated jaws for limiting the magnitude of closing force of the jaws. 
     
     
         12 . The apparatus of  claim 1 , wherein the first jaw comprises a ceramic material having a thermal conductivity of less than 5.0 W/m-K. 
     
     
         13 . The apparatus of  claim 12 , wherein the first jaw comprises an inner member covered with the ceramic material. 
     
     
         14 . The apparatus of  claim 13 , wherein the inner member of the first jaw does not form a part of any electrical conduction path leading to either the first or second heating elements. 
     
     
         15 . (canceled) 
     
     
         16 . (canceled) 
     
     
         17 . A surgical apparatus for welding and severing tissue, comprising:
 first and second relatively movable elongate jaws having jaw-facing surfaces;   an elongated shaft having the first and second relatively movable jaws attached to a distal end thereof;   a first heating element for welding tissue provided on the jaw-facing surface of one of the first or second jaws;   a second heating element for severing tissue provided on the jaw-facing surface of one of the first or second jaws; and   an electrical circuit path within the surgical apparatus including a portion extending along the elongated shaft and through the first and second heating elements in series, wherein upon application of current through the electrical circuit path, the first heating element heats up to a first temperature and the second heating element heats up to a second temperature greater than the first temperature.   
     
     
         18 . The apparatus of  claim 17 , wherein the second heating element is provided on the jaw-facing surface of the second jaw, wherein the first heating element has a wider profile than the second heating element in a plane transverse to the direction of elongation of the first jaw. 
     
     
         19 . The apparatus of  claim 17 , wherein the first heating element has a lower electrical resistance than the second heating element. 
     
     
         20 . The apparatus of  claim 17 , further including a control handle connected to a proximal end of the elongated shaft and a control actuator mounted on the handle for alternately separating and bringing together the jaw-facing surfaces of the elongated jaws, and a force-limiting interface between the control actuator and the elongated jaws for limiting the magnitude of closing force of the jaws. 
     
     
         21 . A surgical method of severing a target tissue while welding the severed ends, comprising:
 providing a surgical apparatus for welding and severing tissue including a pair of jaws adapted to open and close upon the target tissue, the jaws including first and second resistive heating elements;   closing the jaws upon a target tissue;   electrically energizing the first heating element to a first temperature and for a sufficient period of time to form a welded region in the target tissue; and   electrically energizing the second heating element to a second temperature greater than the first temperature to sever the target tissue within the welded region.   
     
     
         22 . The method of  claim 21 , wherein the step of electrically energizing the second heating element is performed after forming the weld in the target tissue. 
     
     
         23 . (canceled)