Initial vector rates in differentiation between supraventricular extrasystoles with aberration and ventricular extrasystoles.

A computer method was constructed for analysing vector rates. Initial vector rates of QRS of ventricular extrasystoles (VES) and of aberrant supraventricular extrasystoles were compared. Bundle branch block (BBB) was used as a model for aberration. Spontaneous VES during heart catheterization and VES found by His-bundle recording represented the VES group. The VES were found to contain a longer average "activation time," i.e. the duration from the onset to the spatial amplitude maximum, than the BBB. The maximum amplitudes were similar. A method for calculating initial vector rate distribution was also developed. This showed a significantly higher proportion of fast rate components in BBB than in VES. The calculation of vector rate distribution gave advantages over the calculation of the mean initial vector rate, when considering electrocardiographic abnormalities such as preexcitation QRS or post-infarction Q waves. With a simple discriminatory analysis using initial vector rate distribution values, a 95% precision was obtained in differentiating between VES and BBB. It is concluded that a QRS from a supraventricular impulse focus with aberration has faster initial vector rates than a QRS from a ventricular focus and that this difference is useful in distinguishing between them.