Left axis deviation in healthy infants and children.

In a series of 1036 routine electrocardiograms, 14 children, without clinical and echocardiographic evidence of heart disease, showed a left axis deviation in the standard electrocardiogram. Six children also had an incomplete right bundle branch block. Left axis deviation is defined as a mean frontal QRS complex axis being -30 degrees or less. The age varied from three months to 10 years, with a clear predominance of males (13/14). The unusual finding of left QRS axis deviation in normal children is emphasized.