Pulmonary Artery Velocity Profiles in Young Lambs

This report describes progress made in our laboratory in examining pulmonary artery velocity patterns in normally maturing lambs. Lambs from four age groups were selected for study--2 days, 1 week, 2 weeks, and 4 weeks. Using an intraluminal 20 MHz pulsed Doppler probe, pulmonary blood velocity was measured at 2 mm intervals across the posterior-anterior and right-left axes, from which 2-dimensional instantaneous velocity profiles were reconstructed. Preliminary computations indicate marked interanimal variability in all groups. Qualitative comparisons of envelope velocity profiles indicate that reverse flow was observed in all groups. Maximal backflow tended to be localized near the walls in the 2 day old group; in the other groups, prominent backflow was observed in the posterior half of the vessel.