The dominance of right to left ventricular mass in the neonatal period which resembles to that of fetal life reverses during the first year. The changes observed in the mean QRS axis (âQRS) in the frontal plane during infancy reflects this. To investigatate this, the ECG of 66 normal neonates were followed up for two years. The mean frontal âQRS shifted from + 127° rapidly to + 79° within two months and to +60° in 6 months. This inverse relationship with age was best explained by a logarithmic function (y=58.2-29.384 Log x; r= -0.73). The 3-97 percentile limits were 86-170° for the neonates, 40-123° at two months and 10-90° for 9 as well as 12 month-old infants. This did not change significantly after age 1.
Keywords: ECG normal course of the first 2 years, the mean QRS axisCopyright © 2024 Archives of the Turkish Society of Cardiology