Automatic "scanning" by radiofrequency in the long-term electrical treatment of arrhythmias.

The use of programmed electrical stimulation in the long term treatment of re-entry tachycardia offers encouraging perspectives. Among the others proposed, the "scanning" system seems to be the most effective. However, an implantable stimulator with these features is not yet available and, thus, a temporary external lead is required. These difficulties have been overcome by utilizing radiofrequency to synchronize and stimulate. An implantable device was therefore designed which is triggered by the patient and automatically searches the interruption zone of the tachycardia by exploring the R-R cycle. The external transmitter, which can produce one or two synchronized impulses, is programmed to scan the R-R cycle with progressive steps of 5 or 10 ms; when tachycardia is interrupted, further stimulation is inhibited. The implanted module connected to an endocavitary lead does not have any power supply and, therefore, is very small. The efficacy of this method has been demonstrated in 4 patients with supraventricular tachycardia (3 with WPW syndrome) resistant to conventional pharmacologic therapy.