Fig. 2.
The effects of sequential ligation of the SAN artery on the heart rate and the leading pacemaking sites. A, Upper panel: epicardial photographs of a perfused right atrial preparation with 3×3 cm optical fields of view. The upper and lower boxes present the optical fields of Fig. a-b and c, respectively. Lower panels: Vm isochronal maps of the RA (a), the superior SAN (b) and the subsidiary pacemaker model (c). B: heart rate changes of the various pacemaker models. The white shaded area is the SAN. SVC: superior rena cava, RAA: right atrium appendage, IVC: inferior vena cava, ISO: isoproterenol, RA: right atrium, Sup: superior, Sub: subsidiary pacemaker, inf: inferior, SAN: sinoatrial node.