In recent years, treatment of cardiac arrhythmias with pacemakers and implantable cardioverter/defibrillators has become increasingly popular. Numerous technical developments have resulted in great advances in this area. International pacing letter coding for use with pacemakers defines the chamber(s) paced, the chamber in which the electrical activity is sensed, and the type of pacing. This also enables the family doctor involved in the care of the cardiac patient to identify the pacemaker system employed and provides him with initial orientation. New developments including VDD pacing, autocapture and autosensing are described and discussed. In a second part, the conditions for the use, and the manner of functioning, of modern implantable cardioverter/defibrillators are explained.