spread over this area by a conductive material that is below the heater as will be described below this creates a temperature gradient which is a particularly advantageous feature of the present invention tissue welding of the type intended to occur in the practice of these inventive methods is discussed in u s pat no 6 908 463 to treat et al which is herein expressly incorporated by reference in its entirety fig1 is a cross sectional view of a handle portion 42 of the embodiment shown in fig1 this is one possible approach for actuating the extension and retraction of the distal tip 18 relative to the elongate outer tube 12 as discussed above though many other suitable configurations may be used alternatively a trigger 44 is slidably disposed on the handle 42 slidable distally through a slot 46 in the direction of arrow 48 and then retractable in the reverse direction a spring 50 within the handle controls pressure and a locking mechanism functions to lock the trigger 44 in the retracted state alternative cutting approaches such as resistive heat hot wire ultrasonic laser or mechanical approaches may be used instead of rf energy if desired for example fig1 illustrates an alternative embodiment wherein a catheter 110.