SIGNAL-AVERAGED ELECTROCARDIOGRAPHIC LATE POTENTIALS IN CHILDREN WITHCOMPLETE HEART-BLOCK

The purpose of this study was to examine signal-averaged electrocardio graphic (SA-ECG) late potentials to predict ventricular arrhythmias du ring intrinsic cardiac rhythm and during ventricular pacing in childre n with complete heart block (CHB). Recordings of SA-ECG were obtained from eight patients (aged 3-18 years) with documented CHB. The etiolog y of CHB was congenital in four cases and acquired in four cases. Six of these patients underwent permanent pacemaker implantation. Comparis ons of the SA-ECG were made before and during ventricular pacing. Abno rmalities of SA-ECG during intrinsic cardiac rhythm were noted in four patients, all of whom were older than 14 years. Although there was no significant difference in SA-ECG parameters between patients with con genital CHB and acquired CHB, abnormal SA-ECG was noted in one of four patients with congenital CHB and in three of four patients with acqui red CHB. Two patients without permanent pacemaker implantation had nor mal SA-ECG, but four of six patients with permanent pacemaker implanta tion had abnormal SA-ECG. Three of the four patients had abnormal SA-E CG during ventricular pacing, but the abnormal SA-ECG in one patient h ad normalized during ventricular pacing. It is important to record SA- ECG before and during ventricular pacing to detect late potentials in patients with CHB. It may be useful to record SA-ECG while changing th e pacing site to find ideal sites for electrode implantation for the p otential prevention of ventricular arrhythmias.