Wireless cardiac pacing system with vascular electrode-stents

An apparatus for electrically stimulating tissue of an animal, which includes a generator (20) that produces a stimulation signal having pulses occurring at a rate corresponding to the rate at which stimulation is desired, a transmitter (22 ) connected to the generator and emitting a radio frequency signal (16) in response to the stimulation signal, and characterized by: a first spiral electrode (30) for implantation within a vein (14) of the animal and by receipt of the RF signal (16), applies an electric current through tissue of the animal.