Ventricular arrhythmias in the long-term postoperative stage of tetralogy of Fallot.

Arrhythmias were studied in 40 patients in the long-term stage after corrective surgery of tetralogy of Fallot. Holter monitoring showed ventricular dysrhythmias in 30 cases. Lown's grade 3 was found in 9, 4a in 5, and 4b in 5 cases. Five patients had ventricular arrhythmias of Lown's 3 or higher grade both in the treadmill stress test and in the Holter ECG. Twenty patients with ventricular arrhythmias of Lown's grade 3 or higher ones were associated with severer hemodynamic, and clinical abnormalities than those with ventricular arrhythmias of lower grade. Supraventricular arrhythmias or bifascicular block are also found in the group with complex ventricular arrhythmias but no cardiac arrest from sinus standstill or complete heart block was observed. Both the age at operation and the years after the corrective surgery were related to the incidence of ventricular arrhythmias of higher grades. Two patients with nonsustained ventricular tachycardia died suddenly during 2 years' follow up period. Tachyarrhythmia seems a major cause of sudden death after repair of tetralogy of Fallot. An electrophysiologic study may be reasonably indicated to prevent sudden cardiac death.