CHANGES IN PULMONARY VENOUS FLOW PATTERN DURING EARLY NEONATAL LIFE

Objective-To investigate serial changes in the pattern of flow in the pulmonary vein during the early neonatal period. Methods-Pulsed Dopple r echocardiography was used to measure flow in the right upper pulmona ry vein in 26 normal newborn infants. Peak flow velocity during systol e (S) and diastole (D) and flow velocity at indents between the systol ic and diastolic fraction (O) and between the diastolic and systolic f raction (X) were measured 1, 4-8, 24, and 96 hours after birth. The he art rate and diameter of the ductus arteriosus were measured simultane ously. Results-Continuous and phasic high flow velocity waveforms were seen 1 and 4-8 hours after birth. The mean (SD) peak flow velocities of X, S, O, and D an hour after birth were 35.2 (13.6) cm/s, 73.1 (23. 1) cm/s, 58.5 (20.5) cm/s, and 81.5 (19.2) cm/s respectively. There we re significant decreases in X, S, O, and D by 24 hours of age (p < 0.0 1 v 1 hour after birth) to 8.1 (10.3) cm/s, 52.8 (18.0) cm/s, 38.6 (14 .5) cm/s, and 54.4 (11.2) cm/s respectively. These results indicate in termittent flow in the pulmonary vein, with flow stopping between dias tole and systole. These flow velocities, X, S, O, and D, correlated we ll with the diameter of the ductus arteriosus (r = 0.80 v X, r = 0.62 v S, r = 0.63 v O, r = 0.75 v D). Conclusion-This serial study showed changes in normal pulmonary vein flow patterns during the early neonat al period. The continuous and high flow velocity waveform that was see n immediately after birth resembled the pattern of pulmonary vein flow seen in congenital pulmonary stenosis and in cases of acute volume ov erload. This waveform may reflect a sudden increase in pulmonary circu latory volume with additional left to right shunting through the ductu s arteriosus in relatively hypoplastic pulmonary veins.