The present case corresponds to a patient with a mitro-aortic valvulopathy of rheumatic origin with syncopal episodes and nauseas, who, in the ECG showed alternatively an extreme sinusal bradycardia and supraventricular tachyarrhythmias. It was interpreted as a typical case of bradycardia-tachycardia syndrome in which the crises of tachyarrhythmias consisted of episodes of double tachycardia with incomplete supra-hisian atrial-ventricular dissociation, documented by obtaining right atrial electrograms and hisian-electrograms during the episodes. Treatment was initiated with verapamil (10 mg intravenously every 8 hours) after an endocavitary pacemaker of demand had been placed. After 3 months the result was very satisfactory with good tolerance to the medical treatment and complete disappearance of the symptomatology.