Pulmonary venous flow from fetal to neonatal period

There are few reports about the effect of fetal or transitional circulation on the pulmonary venous flow. The purposes of this study were to investiga te flow patterns of the pulmonary vein serially from fetal to neonatal peri od and to determine the relationship between pulmonary venous flow and othe r parameters from aortic and mitral valve. Pulmonary venous flow velocity w as analyzed in 21 normal term human fetuses. Postnatal follow-up studies we re performed at 1, 6, 24 h, 3 days, I week and 1 month. In each time point, pulsed Doppler echocardiography was used to interrogate right upper pulmon ary vein, mitral and aortic valve. The measured parameters of pulmonary vei n were heart rate, velocity time integral (VTI), and velocities at systolic peak (S), at diastolic peak (D), at nadir between S and D (O), and at nadi r between D and the next S (X). E/A ratio and VTI were measured for mitral valve and peak systolic velocity and VTI for aortic valve. Pulmonary venous flow in fetus was phasic and continuous with low velocity. One hour after birth, without a change of flow pattern, all Velocities increased dramatica lly. These high velocities showed a significant decrease during 24 h after birth. Three days after birth, the velocity decreased slightly and flow pat tern changed from continuous to interrupted pattern with or without atrial reversal. No Doppler parameters from aortic or mitral valve showed any corr elation with parameters from pulmonary vein. In conclusion, the flow patter n of the pulmonary vein in fetus may result from low pulmonary flow and dec reased capacitance of the pulmonary venous system. Sudden increase in the p ulmonary flaw after birth is likely to be responsible for the highest veloc ities recorded immediately after birth. Left to right shunt through the duc tus arteriosus may also contribute to the Row pattern observed in the first several days, as do changes in reservoir function of the pulmonary vein. ( C) 2000 Elsevier Science Ireland Ltd. All rights reserved.