[Right ventricular flow dynamics in the early neonatal period assessed by pulsed Doppler echocardiography]

Right ventricular hemodynamic changes in the early neonatal period were observed by pulsed Doppler echocardiography in 45 neonates free of organic cardiac disease. Subjects consisted of 19 male and 26 female infants who were categorized by delivery as 22 normals, seven breech presentations, eight vacuum delivery and eight Cesarean section. Asphyxia was present at birth in 11 cases. Echocardiography was performed at 0, 1, 3, 5 and 30 days of age. The pulmonary flow pattern was recorded using the suprasternal long-axis view as a reference, and the maximum pulmonary flow velocity (PaV), acceleration time (AcT) and right ventricular ejection time (RVET) were measured. Mean pulmonary arterial pressure (MPAP) was estimated from the AcT and AcT/RVET ratio, according to Kitabatake et al. The tricuspid flow pattern was recorded with the four-chamber view as a reference, and the peak velocities of rapid filling (R) and atrial filling (A), and the A/R ratio were measured. The A/R ratio of tricuspid flow decreased with age in days and no significant differences were observed on each successive day, but there were significant differences between 0 and 3, 5 and 8 days of age. There were no significant differences by age in days in the maximum velocity of pulmonary blood flow, and the mean value was 74.9 +/- 3.0 cm/sec. The estimated MPAP was maximum at 0 day of age, declined gradually until 5 days of age, and was unchanged thereafter. No significant differences were found according to the type of delivery. Transient tricuspid regurgitation (TR) was detected in nine infants comprised of seven asphyxic infants and two of breech presentations. In these infants with TR, significantly higher estimates of MPAP were observed as compared with those without TR, and the A/R ratio of tricuspid flow was also higher among the infants with TR. These results indicate that the data obtained by this study reflect well acute hemodynamic changes in the early neonatal period in normal infants, and it can be applied for assessing cardiopulmonary disease, as well.