Background. At present the dual chamber pacing, originally developed for patients with AV blockades, is widely used also for patients with Sick sinus syndrome (tachycardic-bradycardic type). But these patients often cause therapeutical problems to their physicians. In these cases either antiarrhythmic therapy is necessary to prevent recurrent supraventricular tachycardias (which are cause of rapid ventricular pacing) or in the case of failure of AA therapy the pacing mode has to be changed to DDI/R, which excludes physiological VAT pacing. The Auto Mode Switching (AMS) function ensures adequate ventricular pacing rate in the time of SV arrhythmias. Methods and Results. Effects of dual chamber pacemakers equipped with AMS were studied in a group of patients with paroxysmal atrial fibrilation and /or atrial flutter. Conclusions. Therapy brings effects in lower of expenses due to less frequent visits at the physician, lower rate of rehospitalisations and lower need for powerful AA therapy.

        Key words: Auto mode switching, Sick sinus syndrome, supraventricular tachycardia.