Echocardiographic growth patterns of intracardiac dimensions and determination of function indices during the first year of life.

Cardiac dimensions and left and right ventricular function indices were studied consecutively in 53 healthy newborn babies throughout their first year of life. Cardiac dimensions, except right ventricular (RV) dimension, increase linearly with age, weight and body surface area, the relation being best described as a linear function of BSA. Left ventricular function indices do no change significantly during the first year of life. Right ventricular systolic time interval ratio (RVPEP/RVET) is high at birth, but declines rapidly during the first hours and days. This change is best described as a parabolic function and is an indicator of the physiological fall of pulmonary vascular resistances.