[Bitachycardia].

One or several episodes of bitachycardia (a simultaneous ventricular tachycardia and atrial tachycardia or fibrillation) were observed in 13 patients. An oesophageal or right atrial endocavitary recording is usually necessary to show the atrioventricular dissociation: even then the diagnosis may be difficult in cases of isorhythmic dissociation or when the ventricular tachycardia is irregular. In 5 cases the double tachycardia appeared to be coincidental. In 7 patients the ventricular tachycardia seemed to be dependant on the atrial tachycardia and could be initiated by a simple spontaneous atrial extrasystole in 3 cases. In one patient the ventricular tachycardia, after a phase of retrograde conduction to the atria, initiated the atrial arrhythmia. The therapeutic indications depend in part on the eventual relationship between the two arrhythmias.