1. A method of treating a patient having epilepsy via an implantable medical device which includes an electrical signal generator coupled to a first electrode and a second electrode where the first electrode is coupled to a main trunk of a vagus nerve of the patient and a second electrode is coupled to a cardiac branch of the vagus nerve of the patient, the method comprising: receiving at least one body data stream; analyzing the at least one body data stream using a seizure detection algorithm to determine an epileptic seizure state; applying a first electrical signal from the electrical signal generator to the main trunk of the vagus nerve using the first electrode as a cathode, based on a determination that the epileptic seizure state of the patient is a first state where an epileptic seizure is not detected; and applying a second electrical signal from the electrical signal generator to the cardiac branch of the vagus nerve using the second electrode as the cathode, based on a determination that the epileptic seizure state of the patient is a second state where the epileptic seizure is detected.