Echocardiographic assessment of left ventricular performance in normal newborns

Left ventricular function was assessed in 72 normal neonates (age 5-15 days, weight 6-10 lbs) using the echocardiographically determined mean velocity of circumferential fiber shortening (VCF). Comparison between mean VCF determined echocardiographically and angiocardiographically in nine infants with congenital heart disease yielded a correlation coefficient of +0.97 (P < 0.001). For the group of normal newborns, mean VCF averaged 1.51 ± 0.04 (SE) circumferences/sec with a range of 0.92 to 2.2 circ/sec. Subgroup values were: <12 hrs (N = 13) 1.48 ± 0.08 circ/sec; 12-24 hrs (N = 16) 1.46 ± 0.05 circ/sec; 24-48 hrs (N = 26) 1.44 ± 0.06 circ/sec; 48-72 hrs (N = 19) 1.57 ± 0.06 circ/sec; 72/150 hrs (N = 8) 1.61 ± 0.11 circ/sec. The differences between age groups were not significant statistically. In contrast, VCF was noted to be depressed significantly in the first hour of life when normal infants were evaluated serially. These studies validate ultrasound determinations of internal shortening velocity in the neonatal period, provide normal values, and attest to the reproducibility of the method. The technique will be especially valuable for the serial, noninvasive assessment of left ventricular performance in newborn infants.