Epicardial electrogram of the right ventricular outflow tract in patients with the brugada syndrome

OBJECTIVES: We tried to record an epicardial electrogram directly, and we examined local electrograms before and after administration of a class IC anti-arrhythmic drug in patients with the Brugada syndrome. BACKGROUND: Electrical heterogeneity of the epicardium in the right ventricular outflow tract (RVOT) has been thought to be related to the Brugada syndrome. However, an epicardial abnormality has not been demonstrated in patients with the Brugada syndrome. METHODS: In five patients with a Brugada-type electrocardiogram (ECG), local unipolar electrograms were recorded at the epicardium and endocardium of the RVOT. To record the epicardial electrogram directly, we introduced an electrical guidewire into the conus branch (CB) of the right coronary artery. The duration of the local electrogram after termination of the QRS complex (DP) was measured before and after class IC anti-arrhythmic drug administration. The signal-averaged electrocardiogram (SAECG) was also obtained in all patients. RESULTS: A definite DP was observed at the epicardium, but not at the endocardium. After administration of a class IC anti-arrhythmic drug, the DP at the epicardium was prolonged from 38 +/- 10 ms to 67 +/- 24 ms. The late potential corresponding to the DP at the epicardium was observed in all patients on the SAECG. CONCLUSIONS: An epicardial electrogram can be recorded from the CB. Recording from the CB enables identification of an epicardial abnormality in patients with the Brugada syndrome. These abnormal electrograms may be related to a myocardial abnormality in the epicardium of patients with the Brugada syndrome.