Effects of internal cardioversion on electrophysiological properties of the right atrium

Aim of this study is to investigate the effects of low energy internal cardioversion (LEIC) on the electrophysiological properties of the right atrial tissue. Thirteen patients were studied, selected a priori for LEIC (increasing energy levels: 1, 2, 3, 5, 7, 10, 15 and 20 J) and monitored by a multipolar basket catheter (32 intra-atrial recordings each patient). The atrial period, the levels of organization and the synchronization have been estimated for each electrogram, over 10-second windows, 10 seconds before and 10 seconds after each shock. Our results suggest that ineffective shocks do not affect the electrophysiological properties of the atria. This is consistent with the hypothesis that even though electrical activation ceases after the shock it spontaneously regenerates within few milliseconds and that the propagation pattern is expression of the organic substrate, which is not affected by an electric shock.