High frequency cardiac arrhythmias and fibrillations are terminated by electric field pacing pulses having an order of magnitude less energy than a conventional cardioversion or defibrillation energy. The frequency and number of the pulses are selected based on a frequency analysis of a present high frequency cardiac arrhythmia or fibrillation. The energy of the pulses is selected from 1/400 to ½ of the conventional defibrillation energy, and the amplitude of the electric field pacing pulses are selected such as to activate a multitude of effective pacing sites in the heart tissue per each pacing electrode. The number and locations of the effective pacing sites in the heart tissue are regulated by the amplitude of the electric field pacing pulses, and by an orientation of the electric field of the pulses.