Abstract: A system for ablating tissue and electrically interfacing with a heart including an electrosurgical instrument, an energy source, and a controller. The instrument includes a shaft maintaining first and second electrodes at a distal section. The electrodes are electrically isolated from one another. The controller controls delivery of energy from the energy source, and monitors electrical signals at the electrodes. The controller is programmed to operate in a monopolar mode and a bipolar mode. In the monopolar mode, the first and second electrodes are electrically uncoupled, and energy from the energy source is delivered to the first electrode in performing an ablation procedure. In the bipolar mode, first and second electrodes are electrically coupled and serve as opposite polarity poles to apply energy to a tissue target site, detect electrical signals at a tissue target site, or both.