Artificial stimulation apparatus comprising a controller 8 comprising a receiver for receiving signal data, a processor 22 for processing received signal data, and a transmitter for transmitting signal data； a sensing stent for location in the proximal coronary sinus of the subject comprising a sensing electrode assembly for sensing atrial and/or ventricular signals from the heart of the subject and a transmitting assembly for transmitting signal data 6 to the receiver of the controller； and at least one stimulation stent (10, 12, 14, 16, 18) for location in at least one vein of the subject distal of the sensing stent comprising a receiver for receiving signal data 20 from the transmitter of the controller and an electrode assembly for providing a stimulating electrical signal to the heart of the subject in response to the data received. A stent assembly for providing stimulation to heart tissue at a target site comprises a stent body of a size to be implanted and retained in the position proximal to the target site； and an electrode assembly arranged to extend longitudinally from the stent body within the target blood vessel in a distal direction from the proximal position to the target site to be stimulated.
