Abstract: An interventional medical device has a capability to sense cardiac dysrhythmias and to selectively respond with one among a hierarchy of therapies appropriate to terminate the sensed dysrhythmia and return the heart of the patient in whom the device is adapted to be implanted to normal sinus rhythm. The device includes a therapy generator having a housing and electronics for conducting bidirectional communication with the patient. The bidirectional communication is carried out by detecting the occurrence of a predetermined dysrhythmia, such as atrial fibrillation, to alert the patient of such occurrence, and by responding to instructions from the patient following such alert for addressing the detected predetermined dysrhythmia. The detection is performed by electrodes mounted directly on the header of the device housing to both detect occurrence of the atrial fibrillation and for alerting the patient thereof by stimulating body tissue such as pectoral muscle in the vicinity of the header electrodes.