Doppler waveforms in the renal arteries of normal children.

Blood velocity waveforms in peripheral arteries vary such that decreasing vascular resistance results in a relative increase in diastolic velocity at steady state. We measured blood velocity in renal arteries of 20 children (age: 119 months +/- 37 months; weight: 38 kg +/- 15 kg) to establish normal values, and to explore the relationship between these waveforms and central hemodynamics. Using image-directed pulsed Doppler echocardiography, M-mode measurements and cardiac index were recorded. Renal hila were visualized via the flank for Doppler sampling. Peak systolic velocity (A) and minimal diastolic velocity (B) were determined. The results (mean +/- SD) were as follows: Renal artery A/B = 2.9 +/- 0.74 (range 1.9 to 5.1). Characteristic waveforms were identical bilaterally and had continuous diastolic forward flow: A/B was independent of central hemodynamics within the resting normal range, varying inversely with age and size.