A valve prosthesis system includes a prosthetic aortic valve and a non-implantable unit. The prosthetic aortic valve includes a plurality of prosthetic leaflets； a frame； a cathode and an anode, which are mechanically coupled to the frame； and a prosthetic-valve coil, which is in non-wireless electrical communication with the cathode and the anode. The prosthetic aortic valve does not include any active electronic components. The non-implantable unit includes an energy-transmission coil； sensing skin ECG electrodes； and non-implantable control circuitry, which drives the cathode and the anode to apply a pacing signal to a heart, detect at least one cardiac parameter using the sensing skin ECG electrodes, and, at least partially responsively to the detected cardiac parameter, to set parameters of the pacing signal, by wirelessly transferring energy from the energy-transmission coil to the prosthetic-valve coil by inductive coupling. Other embodiments are also described.
