[Sequential double demand programmable stimulation in the treatment of resistant supraventricular tachycardia. Long-term results].

Asynchronous pacing at a rhythm slower than that of the tachycardia (underdrive) is an established procedure for the reduction of supraventricular tachycardia. Simultaneous or sequential stimulation depolarising two parts of the circuit (atrium and ventricle) has a greater chance of reducing the tachycardia than stimulation of a single chamber. Five patients with supraventricular tachycardia resistant to antiarrhythmic therapy were treated by sequential pacing in the underdrive mode. Electrophysiological investigations showed a bundle of Kent to be responsible for the ECG appearances of Wolff-Parkinson-White (3 cases) with retrograde conduction only (concealed WPW) in 2 cases. One patient was able to put a stop to his attacks by the application of a magnet over the pulse generator. In four patients, a newly designed pulse generator, based on this concept, was implanted with the property of automatic detection of tachycardia (defined as a heart rate faster than 150/min) triggering almost simultaneous pacing of the coronary sinus and right ventricle (sequential interval of 65 ms) in the asynchronous mode at 77 bpm. The results were reviewed with a follow up of 6 to 36 months. This pulse generator was shown to be effective in both the reduction and prevention of episodes of supraventricular tachycardia. Sequential double demand pacing is a valuable and useful method of treating reentrant tachycardias associated with the WPW syndrome or concealed Kent bundles. It provides an alternative to surgery when the effective refractory period of the Kent bundle is long. Present advances in the field of cardiac pacing will probably result in a widening of the indications for this mode of therapy.