One of the causes of the late deaths after operations of the tetralogy of Fallot are dysrhythmias caused by impaired conduction and automatism. To assess the severity and site of the atrioventricular and intraventricular block the authors used in 19 patients after operation of the tetralogy of Fallot an invasive electrophysiological examination. The authors recommend, based on their own experience, to follow-up on a long-term basis all patients with temporary postoperative complete a-v block. The presence of bifascicular or temporary postoperative a-v block alone does not yet imply the need of a permanent pacemaker. If a serious a-v block persists after the third week or if a syncope or cardiac weakness develops, the authors indicate a permanent pacemaker. Also the development of trifascicular block, even in patients with a normal P-Q interval, detected during fever, physical work or during electrostimulation of the atria is an indication for the introduction of a permanent pacemaker.

Keywords: Adolescent; Cardiac Pacing, Artificial; Child; Electrocardiography; Heart /physiopathology/; Heart Block /etiology/; Humans; Postoperative Complications; Tetralogy of Fallot /surgery/