Fig. 1.
Activation pattern of SAN and surrounding RA during a 0.3 µmol/L isoproterenol infusion. A: isochronal map of Vm. The number on the each isochronal line indicates time (ms). The white-shaded area is the SAN. B: the Vm (blue) and Cai (red) recordings from the superior (a), middle (b), and inferior (c) SANs and the RA (d) are presented in A. C: magnified view of Cai and Vm tracings of the superior SAN. Note the robust LDCAE (solid arrow) before phase 0 of the action potential (0 ms), which in turn was much earlier than the onset of the p wave on ECG. D: the Vm and Cai ratio maps from -60 ms before to 180 ms after phase 0 of the action potential of C. The LDCAE (broken arrows in frames -40 and -20 ms) was followed by the Cai sinkhole during early diastole (solid arrow in frame 180 ms). This figure was reproduced with permission from Joung et al.29) SAN: sinoatrial node, RA: right atria, LDCAE: late diastolic Cai elevation.