Post-pacing T loop abnormalities

Japanese Heart Journal
T TsutsumiK Harumi


Vectorcardiograms of paced and unpaced beats were recorded from 18 patients with implanted pacemakers to investigate the characteristics of post-pacing T inversions. The intraventricular conduction during sinus rhythm of unpaced beats was normal in 13 of 18 patients and abnormal in the other 5 (RBBB in 3, LBBB in 2). The directions of the maximum QRS vector in paced beats (max QRSp.V) and maximum T vector in unpaced beats (max T unp.V) were studied. In 8 of 13 patients with normal intraventricular conduction (group A) and in 3 patients with right bundle branch block (RBBB), the differences between the directions of max QRSp.V and max T unp.V in both frontal and horizontal planes were less than 30 degrees, and in 5 of 13 patients with normal intraventricular conduction (group B) and 2 patients with left bundle branch block (LBBB), differences exceeded 30 degrees. The direction of max T unp.V tended to be superiorly, posteriorly and to the right regardless of max QRSp.V direction. The similarity in direction of max QRSp.V and max T unp.V supports the hypothesis by Rosenbaum et al that post-pacing T inversions may be, in part, explained on the basis of 'cardiac memory'. However the absence of correlation between the max QRSp.V and...Continue Reading


Jan 1, 1995·Journal of Electrocardiology·K HarumiY Okamoto
May 29, 1998·Circulation·A ShvilkinM R Rosen

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