Angular velocity of the QRS loop of the vectrocardiogram in the normal heart

Angular velocity expressed in radians/sec of the rotation movement of the QRS loop at intervals of 2.5 msecs was calculated from a computer program written in Fortran IV. Frontal, horizontal and left sagittal planes were recorded in 125 normal subjects for analysis. The range of angular velocity for 375 QRS loops was from a few radians/sec to a maximum of 95 radians/sec. Average values of maximum angular velocities were: frontal plane, 46.2 radians/sec, horizontal plane, 41 radians/sec, and left sagittal plane, 34.1 radians/sec. Angular velocity expressed as a periodic function of the vector loop is characterized by polyphasic curves. In the frontal plane, curves tend to be more symmetrical with maximum values in the middle. Angular velocity curves are an alternate expression of analysis of planar vector loops employed in clinical practice. Their normal ranges are given in this paper.