Catheter systems, tools and methods are disclosed for the selective and rapid application of DC voltage to drive irreversible electroporation, with the system controller configurable to apply voltages to an independently selected subsets of electrodes, such that voltages of one polarity are applied to a multiplicity of electrodes on a first medical device and voltages of the opposite polarity to a multiplicity of electrodes on a second medical device. The first and second medical devices can be epicardial catheters positioned such that their opposing distal tips are approximately aligned and whose segments with electrodes collectively wrap around the pulmonary veins.
