[Atrial defibrillators or implantable atrioverters.  Initial results]. 
The atrial defibrillator is a new non-pharmacological treatment of atrial fibrillation (AF) for restoration of sinus rhythm.  This device has two programmable modes: automatic or activated by the physician or patient.  In the automatic mode, the device delivers a shock synchronous with the R wave to restore sinus rhythm when AF is detected.  Two patients with paroxysmal AF resistant to pharmacological therapy were included in a study to assess the efficacy and safety of the atrial defibrillator in the mode activated by the physician.  The device implanted in the pectoral region is connected to 3 electrodes, two for atrial defibrillation and sensing positioned in the coronary sinus and right atrium respectively and a sensing and pacing electrode in the right ventricle.  The right ventricle is paced if a post-shock pause is detected.  It is possible to interrogate the device with a programmer using its Holter function and so determine the number of episodes of AF sensed and treated.  The number, intensity and energy of the shocks and the parameters of ventricular stimulation are programmable.  In these two patients, the atrial defibrillator effectively reduced prolonged episodes of AF with a follow-up of 12 and 7 months.  No pro-arrhythmic effects were observed.  Further clinical evaluation is under way to assess this new mode of treatment, including the mode activated by the patient, safety and tolerance of the shocks.  In our two patients, the treatment of prolonged episodes of AF was followed by reduction of many short or asymptomatic episodes.