[Atrial complex of the differentially augmented ECG in sinus and atrial rhythms of the dog]

In 27 dogs, the sinus rhythm and ectopic atrial rhythms induced with bipolar epicardiac atrial pace-maker, were studied on the basis of analysis of high amplitude atrial complex in augmented (150-250) filtered (30 divided by 110 Hz) ECG, intraatrial ECG in open heart, and the P wave of the ECG from the body surface. The atrial complex at sinus rhythm has a constant and typical form. Various forms of atrial ectopic complexes aided to detect pace-maker site. The recording of high-amplitude atrial complex revealed the sequence of atrial depolarization more precisely than the P wave of the body surface ECG.