The therapeutic role of chronic cardiac pacing in cardiology has significantly altered for two fundamental reasons: a) on the one hand, there has been a widespread increase in the indications for cardiac stimulation, and consequently, today, approximately 50% of the patients with pacing do not suffer from advanced atrioventricular (A-V) block or syncopal attacks, but are frequently suffering from other pathological conditions: episodes of paroxysmal arrhythmia, atrial disease, depression of the habitual pacemaker by drugs or in the course of cardiomyopathy; b) on the other hand, through technological progress the life of the generator has been lengthened (lithium, plutonium), more variable frequencies within relatively high limits are available, electrodes, wiring, circuits etc. have improved. This extended use of the pacemaker, however, creates in itself a series of problems: it is now possible to envisage the characteristics of the "ideal" pacemaker, in other words, a stimulation unit endowed with resistance, modulation, self-control, innocuosness.