[Idiopathic sick sinus syndrome with a-v and intraventricular conduction disturbances in a child. (first report in childhood) (author's transl)].

This report presents a ten-year old child suffering from sick sinus syndrome, in the "Bradycardia-tac hycardia-asystole" variant. A long observation and an ECG made when he was 7 have never shown a sinusal rhythm. An involvement of the A-V node is also present, made clear by a block of the second degree with not very high atrial rates and by prolonged refractory periods, as well as an involvement of the intraventricular conduction, made evident by an incomplete right bundle branch block and by a long refractory period of the anterior fascicle. The clinical, laboratory and hemodynamic data excluded either a congenital or an acquired cardiopathy. The ECGs of the patient's relatives excluded a familiar type of S.S.S. It is, therefore, an idiopathic S.S.S., which is very rare in children. The nosological set in the still vague field of the idiopathic degenerations of the conduction tissue is discussed.