[Accelerated idioventricular rhythm wih isorhythmic A-V dissociation. An electrophysiological study (author's transl)].

Three cases of accelerated idioventricular rhythm with isorhythmic A-V dissociation are presented. One case was affected by hypertrophic non obstructive myocardiopathy and two cases were affected by coronary heart disease with previous myocardial infarction. In all the cases of the arrhythmia persisted for days or months. By means of the electrophysiological study we could establish that 1) the focus was not protected by entrance block and 2) it was localized in the main branches of the conduction system. In the first case the focus was localized in the right bundle branch, in the second case, it was localized in the anterior fascicle of the left bundle branch and in the third case in the posterior fascicle of the left bundle branch. These electrophysiological characteristics suggest that the arrhythmia was due to increased firing of normal idioventricular pacemakers. On the basis of this electrogenetic interpretation we outline that in our cases the term of accelerated idioventricular rhythm should be preferred to others used in literature such as slow ventricular tachycardia.