Reference ranges for cardiac dimensions and blood flow velocity in preterm infants.

Abstract

To establish reference ranges for cardiac dimensions and Doppler measurements in preterm infants. 79 infants of less than 34 weeks' gestation were examined by echocardiography on days 0, 7, and 28 after birth, to produce a set of reference ranges and to examine changes in these indices over the first month of life. The following dimensions were measured: interventricular septum, left ventricular posterior wall, left interventricular diameter at end systole and diastole, left atrium, and aortic root; Doppler measurements were made of maximum blood flow velocity (Vmax) through the pulmonary, aortic, mitral, and tricuspid valves. Reference ranges are given. Cardiac dimensions correlated well with gestation and birth weight but Vmax did not. There was a significant increase in measurements over time. The "normal" preterm infant also appeared to often have asymmetrical septal hypertrophy. Antenatal dexamethasone administration did not appear to affect the measurements. There is a close correlation with both gestation and birth weight for all physical measurements. Echocardiograms in preterm babies clearly differ from those in older children and adults.