Blood flow velocity profiles in pulmonary branch arteries in lambs

We studied the detailed profiles of blood flow in the right and left pulmonary arteries using 20 MHz pulsed Doppler ultrasound equipment in a lamb model. Fourteen lambs aged four to six weeks were selected. In six lambs, monocrotaline pyrrole was injected parenterally to create pulmonary hypertension (PH group). Eight other lambs served as unaltered controls (control group). The blood flow velocities were sampled in 1mm increments along the anterior-posterior axis of the branch arteries. The maximum velocity of the forward flow in the left pulmonary artery was higher than that in the right pulmonary artery in the control group (71.7 +/- 15.9 cm/s vs 60.2 +/- 13.5; p < 0.05). The fastest backward flow was located at the posterior position of the vessel in the right pulmonary artery in the control group (71.7 +/- 15.9 cm/s vs 60.2 +/- 13.5; p < 0.05). The fastest backward flow was located at the posterior position of the vessel in the right pulmonary artery in the control group. No significant bias in location was shown in the left pulmonary artery. Using indices of P90, acceleration time, P90*AcT, the velocity waveforms in the PH group were compared with those in the control group. In the left pulmonary artery, every index in the control group showed a significantly greater value that in the PH group. On the other hand, no significant differences were found between either group in the right pulmonary artery.