Modern, microprocessor-controlled antitachycardia pacemakers are available with extended detection and termination programs for the treatment of supraventricular tachycardias. Using the "InterTach 262-12" we examined a universal antitachycardia pacing mode in the chronic state. Based on the individual electrophysiologic parameters, a defined burst stimulation mode was used for the first intervention and, consecutively, a determined scanning mode. The InterTach device was implanted in 17 patients with a mean age of 50 +/- 15 years: 10 with AV-nodal reentrant tachycardia, 6 with Wolff-Parkinson-White syndrome, 1 with reentrant tachycardia with Mahaim fibers. The mean tachycardia rate was 178 +/- 23/min and the follow-up 10 +/- 4 months. Every 3 months the efficacy of the termination mode was tested by programmed stimulation in supine and upright body position or during physical activity. In these tests, a rate of 95-100% successful terminations was observed. In the chronic state, 26 persistent tachycardias in 11 patients were noted; 21 episodes could be referred to an insufficient tachycardia detection. Only four persistent tachycardias were due to ineffective antitachycardia pacing. The introduction of extended variable termination programs, including consecutive, flexible pacing modes, can be considered as a marked advancement in the antitachycardia pacemaker therapy for supraventricular tachycardias.