LEFT ATRIAL RHYTHM - ANALYSIS BY INTRA-ATRIAL ELECTROCARDIOGRAM AND VECTORCARDIOGRAM

An analysis of the intra-atrial electrocardiogram and the vectorcardiogram was undertaken in 4 patients whose 12 lead scalar electrocardiograms suggested a so-called left atrial rhythm. In all cases the direction of the P loop by vectorcardiographic analysis differed from the postulated direction obtained by analysis of the scalar electrocardiogram. In all cases a nodal (A-V junctional) site for pacemaker activity appeared more likely than a left atrial site. The intra-atrial electrocardiogram did not appear to be helpful in differentiating a nodal (A-V junctional) rhythm from a left atrial rhythm. We strongly suspect, therefore, that the diagnosis of left atrial rhythm by the electrocardiogram is still a troublesome one, and deserves further confirmation utilizing the intra-atrial electrocardiogram and the vectorcardiogram. © 1968.