142 ELECTROPHYSIOLOGIC EVALUATION OF TETRALOGY OF FALLOT TOF REPAIR: EARLY POSTOPERATIVE STUDIES

Abstract

Cardiac arrhythmias are common after repair of TOF and are associated with sudden death. We performed 9 electrophysiologic studies in 5 patients (pt.), ages 6-16 yrs. with TOF 1-26 days after repair to identify pt. at risk for arrhythmias. Rapid atrial pacing and programmed atrial and ventricular stimulation were carried out using intracardiac catheters (2 pt.-2 studies) or epicardial pacing wires placed intraoperatively on the right atrium, right ventricular apex (RVA) and outflow tract (RVOT, 5 pt.-7 studies). Epicardial pacing studies were performed at the bedside or in the intensive care unit (ICU). Junctional rhythm was present at the first study in 2 pt. Wenckenbach periodicity occurred at an average cycle length of 236 + 88 Msec. Dual pathway atrio-ventricular conduction, anterograde and retrograde, was observed in 1 pt. Atrial flutter was induced in 1 pt. Ventricular effective (VERP) and functional (VFRP) refractory periods (RP) determined at the RVA (VERP 193.8 ± 19.3, VFRP 212.5 ± 19.8 mesc) and RVOT (VERP 197.5 ± 19.2, VFRP 215.3 ± 19.3 msec) were similar. The ventricular RP determined by intracardiac or epicardial stimulation were identical. Repetitive ventricular responses were observed in 1 pt. Single (S1, S2) or double (S1, S2, S3) extrastimuli failed to induce ventricular arrhythmia. These observations suggest that electrophysiologic studies can be safely carried out in the immediate post operative period at the bedside or in the ICU and may be helpful in identifying pt. at risk of developing cardiac arrhythmia.