[Supraventricular paroxysmal tachycardias. Electrophysiological studies]

Two cases of paroxysmal supraventricular tachycardia are presented. The electrophysiological study has established that in the first patient arrhythmia was induced by an ectopic focus unprotected by entrance block localized in the lower part of the atrium, while in the second patients paroxysms implied the presence of a mechanism of re-entry due to the existence of a Kent bundle. The identification of the electrophysiological characteristics is therefore essential to the proper administration of anti-arrhythmia drugs.