Figure 2.

Activation map and intracardiac electrograms of premature atrial contractions (PACs). A: The activation map of the left atrium, showing centrifugal activation with widespread breakthrough in the anterior wall. The unipolar signal recorded at the earliest activation site showed an rS pattern (yellow arrow). B, C: Intracardiac electrograms recorded when the mapping catheter (MAP) was positioned in the anterior wall (B) and right superior pulmonary vein (C). CS = coronary sinus; LSPV = left superior pulmonary vein; MA = mitral annulus; RIPV = right inferior pulmonary vein; RSPV = right superior pulmonary vein.