Normal intracardiac electrograms obtained during invasive electrophysiologic study (EPS)

The normal intracardiac electrograms, during sinus rhythm, obtained during an electrophysiologic study are shown. Three surface electrocardiogram (ECG) leads are monitored (I, aVF, and V1); intracardiac electrograms are obtained from the high right atrium (HRA); the proximal (p), mid (m), and distal (d) bundle of His (HBE); the p, m, and d coronary sinus (CS); and right ventricular apex (RVA). For an ablation procedure, an exploratory catheter (exp) is also used for more extensive mapping. The electrogram obtained includes those from the atrium (A), bundle of His (H), and ventricle (V).