The Evolution of the vectorcardiogram and electrocardiogram of the normal infant: I. The normal newborn ∗

Abstract

1. 1. Vectorcardiograms and electrocardiograms were obtained in fifty normal newborn infants. 2. 2. Typically, the vectorcardiographic findings were similar to those found in cases of pathologic right ventricular hypertrophy in older children and adults with two possible exceptions: (1) T sÊ loops were almost always concordant with the QRS sÊ loops in all planes in the normal newborn; and (2) the QRS sÊ loop was usually inscribed in a clock-wise direction in the sagittal plane in the normal newborn. 3. 3. Variations from the typical vectorcardiographic findings were seen including: (1) QRS sÊ loops oriented predominantly to the left in some, superiorly in others and posteriorly in still another group; (2) counterclockwise direction of inscription of the QRS sÊ loop in the frontal and horizontal planes. 4. 4. In general, the electrocardiograms showed varying degrees of right axis deviation and evidence of “right ventricular preponderance” in the precordial leads. 5. 5. Deviations from typical electrocardiographic findings were also encountered including: (1) precordial lead patterns suggestive of “left ventricular preponderance”; and (2) T wave changes heretofore described as indicative of pathologic ventricular hypertrophy. These included upright T waves in right precordial leads of infants more than one day old and inverted T waves in left precordial leads of the same age group. 6. 6. Arrhythmias were present as follows: five infants with ventricular premature systoles, one with nodal premature systoles, one with atrial premature systoles and one with a wandering pacemaker. 7. 7. Because of the wide range of normal, conservatism is urged in the interpretation of the vectorcardiogram and electrocardiogram of the newborn infant.