Serial Pulsed Doppler Assessment of Pulmonary Artery Pressure in Very Low Birth-Weight Infants

We assessed pulmonary artery pressure (PAP) during the early neonatal period in very low birth-weight (VLBW) infants using serial echocardiographic measurements of the ratio of the pulmonary artery acceleration time to the right ventricular ejection time corrected by heart rate [AT:RVET(c)]. Eighty-four VLBW infants weighing less than 1500 g were examined using serial color Doppler echocardiography from 3 hours to day 7 after birth. The AT:RVET(c) of infants born after 30 weeks of gestation showed a rapid, significant increase during the early neonatal period, whereas those of the groups born at less than 30 weeks showed no significant increase before day 14. At 24 hours after birth, the AT:RVET(c) values of VLBW infants did not correlate well with either the ratio of the right preejection period to the right ventricular ejection time on M-mode echocardiography or the pressure gradient between the right ventricle and the right atrium, as estimated by tricuspid regurgitation on pulsed Doppler echocardiography. The AT:RVET(c) value for the chronic lung disease (CLD) group did not differ significantly from that for the oxygen-dependent group at any assessment point. During the early neonatal period, the AT:RVET(c) of VLBW infants, as calculated by pulsed Doppler echocardiography, differed with their gestational age and did not appear to correlate well with PAP. Our data also suggest that AT:RVET(c) values may not be a good predictor of the subsequent occurrence of CLD in VLBW infants.