[Evolutive study of the vectorcardiogram from the 14th day to the 6th month of life on the normal infant].

With the purpose of a better evaluation of the changes of cardiac potentials during the early hemodynamic arrangement of the normal heart, the authors analyze the VCG of 10 normal children periodically recorded from the 14th day to the 6th month from birth. Rotation of QRS, T and P loops in the three planes, direction and voltage of principal planar and spatial vectors were analyzed. The QRS loop showed a balanced distribution between right and left ventricular forces in the second week and developed a leftward orientation from the 4th week to the 3rd month, as demonstrated both by the loss of clockwise rotation of horizontal QRS loop and by the progressive leftward and backward direction of intermediate vectors. The initial vectors were sketched or absent in the 14th day and increased successively until the typical Q loop. The voltage of terminal vectors did not change in the course of time, but the S loop in the horizontal plane lost its original clockwise rotation and shifted to middle posterior line. The T loop progressively shifted backward so that it was always posterior after the 30th day. The P loop in the frontal plane was similar to the adult's one while in the horizontal plane it often presented a figure-of-eight. The semeiological aspects and the electrogenic considerations of these changes were discussed.