[Repetitive supraventricular tachycardia. Case report and electrophysiologic bases]

A typical case of repetitive supraventricular tachycardia is reported. Periods of normal heart rate are interrupted by short bursts of supraventricular tachycardia. In the case described this phenomenon can be explained by coexistence of reentry and an automatic rhythm from a subsidiary pacemaker. This pacemaker was found to be in the bundle of His; its automaticity showed a rate somewhat faster than that of the sinus node. Careful analysis of the surface electrocardiograms allowed a definition of the electrophysiologic events starting a run of tachycardia. The circus movement entertaining the tachycardia itself was found to result from AV nodal reentry.