A high density mapping and ablation catheter, comprising: an elongate catheter body having a distal region; a tip electrode positioned at a distal end of the distal region; at least five ring electrodes disposed proximally of the tip electrode within the distal region, wherein the at least five ring electrodes are segmented; a plurality of conductors extending through the elongate catheter body, at least one conductor of the plurality of conductors electrically connected to the tip electrode and at least one conductor of the plurality of conductors respectively electrically connected to each electrode of the at least five electrodes; and at least one connector configured for connection to a source of ablation energy, an electrophysiology mapping device, and a programmable electric stimulator, wherein the plurality of conductors are electrically connected to the at least one connector such that: the tip electrode can be electrically coupled to the source of ablation energy, thereby to deliver ablation energy to a tissue, the electrophysiology mapping device, thereby to measure electrophysiological activity in the tissue, and the programmable electric stimulator, thereby to apply a pacing stimulus to the tissue, and each electrode of the at least five ring electrodes can be electrically coupled to the electrophysiology mapping device, thereby to measure electrophysiological activity in the tissue, and the programmable electric stimulator, thereby to apply a pacing stimulus to the tissue. an elongate catheter body having a distal region; a tip electrode positioned at a distal end of the distal region; at least five ring electrodes disposed proximally of the tip electrode within the distal region, wherein the at least five ring electrodes are segmented; a plurality of conductors extending through the elongate catheter body, at least one conductor of the plurality of conductors electrically connected to the tip electrode and at least one conductor of the plurality of conductors respectively electrically connected to each electrode of the at least five electrodes; and at least one connector configured for connection to a source of ablation energy, an electrophysiology mapping device, and a programmable electric stimulator, wherein the plurality of conductors are electrically connected to the at least one connector such that: the tip electrode can be electrically coupled to the source of ablation energy, thereby to deliver ablation energy to a tissue, the electrophysiology mapping device, thereby to measure electrophysiological activity in the tissue, and the programmable electric stimulator, thereby to apply a pacing stimulus to the tissue, and each electrode of the at least five ring electrodes can be electrically coupled to the electrophysiology mapping device, thereby to measure electrophysiological activity in the tissue, and the programmable electric stimulator, thereby to apply a pacing stimulus to the tissue. the tip electrode can be electrically coupled to the source of ablation energy, thereby to deliver ablation energy to a tissue, the electrophysiology mapping device, thereby to measure electrophysiological activity in the tissue, and the programmable electric stimulator, thereby to apply a pacing stimulus to the tissue, and each electrode of the at least five ring electrodes can be electrically coupled to the electrophysiology mapping device, thereby to measure electrophysiological activity in the tissue, and the programmable electric stimulator, thereby to apply a pacing stimulus to the tissue.