An implantable system comprising a first device, also called a centralisation device, suitable for being implanted in a fixation position inside the patient's body and at least one second device suitable for stimulating an organ of the patient when the second device is implanted, in a stimulation position, in the patient's body. The first device being further configured to command a stimulation of the organ by the second device. The implantable system being characterised in that the organ is a separate organ from the stomach and in that, when the first device is in the fixation position, the first device is accommodated in the patient's stomach and fixed to a stomach wall.