Doppler ultrasonography of the human fetal pulmonary circulation.

J.A.M. Laudy', M.A.J. de Ridder', J. W. Wladimiroff' Department of Obstetrics and Gynaecology, University Hospital Rotterdam, Institute of Epidemiology and Biostatisticsl, Erasmus UniverSity Medical School, Rotterdam, The Netherlands Published in: Pediatric Research 1.997;41:897-901 The objective of the present study was to determine the characteristics of Doppler flow velocity waveforms in branch pulmonary arteries in relation to gestational age. A total of 111 singleton normal pregnancies were studied during the second half of pregnancy using a combined color-coded Doppler and two-dimensional real-time ultrasound system. Pulsed Doppler measurements of the most proximal branch of the right or left pulmonary artery were attempted during fetal apnea from a transverse cross-section of the fetal chest at the level of the cardiac four-chamber view after visualization with color Doppler. The success rate in obtaining the pulmonary arterial waveform was 85%. The waveform displayed a rapid systolic velocity acceleration, followed by an initially rapid but then more gradual velocity deceleration which was interrupted in most cases by a short reversed flow interval at the beginning of the diastolic phase of the cardiac cycle. The diastolic phase was characterized by forward flow. Peak systolic, end-diastolic and time-averaged velocity, pulsatility index and systolic integral remained constant during gestation. Changes in vessel diameter or compliance may play a role in this. A gestational agedependent rise was established for peak diastolic veloCity, diastolic integral and early peak diastolic reverse flow, whereas a gestational age-determined