Vectorcardiographic studies in infants and children: I. Comparative orthogonal lead studies in the neonatal period

Abstract

Planar vectorcardiographic QRS loops of 33 normal, term infants were recorded by the Grishman cube, Frank and McFee-Parungao axial lead-placement systems on the first through the third days of life. No changes occurred in direction of loop inscription or in magnitude of the mean and maximal planar and spatial QRS vectors that might reflect changing ventricular loading patterns during the period of transition from the fetal to adult circulation. In this group of infants the orthogonal systems performed quite similarly; the major differences observed among recordings were in the magnitudes of the recorded X, Y and Z deflections, which were greatest for the axial system and smallest for the Frank system. On successive days of life, mean and maximal QRS vectors were of a similar, but not identical, order of magnitude and orientation for a given lead system, but in individual instances wide deviations were observed. In general, in most infants QRS vector directions were right, inferior and anterior, thus reflecting the expected electrical and anatomic preponderance of the right ventricle at this age. The cube system, an unweighted lead system based on geometric placement of skin electrodes, performed in approximation to the orthogonal systems. It was, in general, a technically unsatisfactory system, even though electrode placement seemed to offer the advantage of fewer electrodes. Tracings in general were small, with considerable noise level produced by body tremor; this factor, together with the small signal, produced a small signal to noise ratio. These data will be expanded to encompass measurements from a much larger series of infants, with more detailed, extensive analysis made possible through the use of digital computer technics.