A quantitative study of initial and terminal QRS vectors in a group of normal older men

Abstract

1. 1. The initial and the terminal 10, 20, 30, and 40-msec. vectors of the QRS complex were statistically analyzed in 93 normal older men. These initial and terminal vectors were presented as mean values of azimuth, elevation, and magnitude, with standard deviations for each angular and linear speed of the sweep. 2. 2. The initial QRS vectors point more forward, the terminal QRS vectors point more backward, and the magnitude of all instantaneous initial and terminal vectors is smaller in a group with wide QRS than in a group with narrow QRS. 3. 3. The electrical axis in the frontal plane did not correlate with azimuth, magnitude, or angular or linear speed of the initial or terminal vectors. 4. 4. The initial 40-msec. vector and the mean QRS vector are so similar in direction and magnitude that the 40-msec. vector cannot be truly considered as an initial vector.