Abstract: Systems and methods for diagnosing and treating cardiac disorders transmit an electrical energy pulse that temporarily stuns a zone of myocardial tissue, temporarily rendering it electrically unresponsive. The systems and methods sense an electrophysiological effect due to the transmitted pulse. The systems and methods alter an electrophysiological property of myocardial tissue in or near the zone based, at least in part, upon the sensed electrophysiological effect. The alteration of the electrophysiological property can be accomplished, for example, by tissue ablation or by the administration of medication. In a preferred implementation, radio frequency energy is used to both temporarily stun myocardial tissue and to ablate myocardial tissue through a common electrode.