Abstract: A method and apparatus for detecting and treating atrial fibrillation. In response to detecting atrial fibrillation, the device derives an escape interval based on one or more preceding intervals between ventricular depolarizations. The escape interval is initiated in response to a ventricular depolarization, and in response to the expiration of the escape interval, an atrial cardioversion pulse is delivered. In one embodiment of the invention, the cardioverting pulse is delivered immediately upon expiration of the derived escape interval. In a second embodiment of the invention, a ventricular pacing pulse is delivered on expiration of the escape interval, with an atrial cardioversion pulse following after a short delay.

Abstract: A method and apparatus for pacing the atrium to reduce the incidence of dangerous arrhythmias. Electrodes are located at least two locations within the atrium, preferably in the triangle of Koch and/or an area of prolonged effective refractory period elsewhere within the atrium. Additional or alternative electrode locations may also be employed. The apparatus defines a variable interval following atrial depolarizations, based on the detected rate of the depolarizations. In response to a sensed depolarization at one of the locations, outside the variable interval, pacing pulses are delivered at least to the electrodes located at the other locations. Demand atrial pacing using some or all electrodes is also provided.