[Late potential is useful to evaluate myocardial damage after surgical repair of tetralogy of Fallot].

In the long-term postoperative stage of patients with tetralogy of Fallot, the event free rate gradually decreases and the arrhythmia problem becomes prominent. Especially, myocardial damage of the right ventricular outflow tract (RVOT) is the last risk factor of ventricular arrhythmias in the postoperative stage. Late potential (LP) recorded by signal averaging is a new marker for evaluating the prognosis of ventricular arrhythmias in comparison with the programmed electrical stimulation method. By the multiphasic oscillation method in about 50% patients, the LP was detectable, implying myocardial damage in RVOT due to infundibular myocardial resections. With the use of the backward filter, there was no "ringing" artifact in the ST segment.