Aortic run-off in children with arterial shunts or persistent arterial duct—characteristics of flow detected by Doppler techniques in the descending aorta

Flow in the descending aorta was studied to characterize aortic run-off in patients with shunts at the arterial level. Pulsed Doppler examination of descending aortic flow was performed with simultaneous estimation of ratios of shunt-to-systemic flow (shunt flow ratio) at cardiac catheterization. We studied 14 patients with shunt-dependent circulations, eight patients with isolated persistence of the arterial duct, 11 normals and five patients immediately after umbrella occlusion of their persistent arterial duct. Parameters of diastolic flow were standardized to systolic parameters. The ratio of diastolic velocity to the time integral (velocity/time integral retrograde diastolic flow ÷ velocity/time integral systolic flow) ranged from 1×10−1−10.8×10−1. Shunt flow ratios ranged from 0.1−3.9. Pandiastolic retrograde flow was seen in 21 of 22 patients with shunts at the arterial level (the ratio was 0.1 in the remaining patient). No normal patient exhibited pandiastolic retrograde flow. Of the five patients undergoing ductal closure, three exhibited persistent pandiastolic retrograde aortic flow following effective occlusion. The ratio of diastolic velocity to the time integral correlated with the ratio of shunt flow (r=0.76, standard error 0.7). A diastolic velocity/time integral ratio of greater than 8.5×10−1 (sensitivity 67%, specificity 94%) selected patients with shunt flow ratio greater than two, and a diastolic velocity/time integral ratio of less than 5×10−1 (sensitivity 100%, specificity 94%) selected shunt flow ratios of less than 0.5.