depolarization of the atrioventricular junctional tissues and of the atrial septum was examined in the perfused dog heart before and during ventricular fibrillation by ( 1 ) recording the potentials from the junctional tissues in the regions of the interatrial and interventricular septum and examining the relationship of activity at these sites to atrial depolarization , ( 2 ) computing histograms and autocorrelograms of atrial firing intervals to study atrial rhythmicity , and ( 3 ) plotting the sequence of atrial septal depolarization .
C0018787
heart
C0018792
atrial