Jaw structure for electrosurgical instrument and method of use
An electrosurgical medical device and technique for creating thermal welds in engaged tissue that provides very high compressive forces. In one exemplary embodiment, at least one jaw of the instrument defines a tissue engagement plane carrying first and second surface portions that comprise (i) an electrically conductive material and (ii) a positive temperature coefficient (PTC) material having a selected increased resistance that differs at each selected increased temperature over a targeted treatment range. One type of PTC material is a doped ceramic that can be engineered to exhibit a selected positively sloped temperature-resistance curve over about 37° C. to 100° C. The 70° C. to 100° C. range can bracket a targeted “thermal treatment range” at which tissue welded can be accomplished. The engineered resistance of the PTC matrix at the upper end of the temperature range will terminate current flow through the matrix. In one mode of operation, the engagement plane cause ohmic heating within tissue from Rf energy delivery tissue PTC matrix is heated to exceed the treatment range. Thereafter, energy density in the engaged tissue will be modulated as the conductivity of the second portion hovers within the targeted treatment range to thereby provide optical tissue heating for purposes of tissue welding.
1. A working end of a medical device, the working end comprising:
a jaw assembly defining opposing jaw portions moveable between an open position and a closed position relative to an axis; at least one jaw defining a proximal cam surface portion and a distal cam surface portion, the cam surface portions being proximal and distal respectively to a rotation point of the at least one jaw in open and closed positions;
an axially reciprocatable member carried by the working end, the reciprocatable member having spaced apart first and second cam surfaces for engaging said proximal and distal cam surface portions of said at least one jaw, respectively; wherein extension of said reciprocatable member causes said second cam surface to slidably engage the distal cam surface portion of the at least one jaw to move the jaw assembly toward the closed position; and
wherein retraction of said reciprocatable member causes said first cam surface to slidably engage the proximal cam surface portion of the at least one jaw to move the jaw assembly toward the open position wherein both jaw portions define an axially-extending channel for slidably receiving a transverse element of the reciprocatable member.
2. The working end of claim 1 , further comprising electrical energy delivery means positioned in at least one of the jaws portions.
3. The working end of claim 1 , wherein the reciprocatable member is configured to cut tissue.
4. The working end of claim 1 , wherein the reciprocatable member defines a distal blade edge for transecting tissue.
5. The working end of claim 1 , wherein the reciprocatable member carries a distal cutting electrode for transecting tissue.