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This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: 297/4/R1171    most recent 00384.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Smolich, J. J. Articles by Penny, D. J. PubMed PubMed Citation Articles by Smolich, J. J. Articles by Penny, D. J.

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Ductus arteriosus wave intensity analysis in fetal lambs: midsystolic ductal flow augmentation is due to antegrade pulmonary arterial wave transmission

¹Heart Research Group, Murdoch Children's Research Institute, ²Department of Paediatrics, University of Melbourne, and ³Department of Cardiology, Royal Children's Hospital, Melbourne, Australia

Submitted July 6, 2009 ; accepted in final form August 13, 2009

In midsystole, fetal pulmonary trunk (PT) and arterial (PA) blood flows characteristically fall, despite pulmonary blood pressure increasing, while ductus arteriosus (DA) flow continues to rise to a delayed peak. Wave intensity (WI) analysis indicates that midsystolic fetal PT and PA flow reductions are related to a very large midsystolic PA backward-running compression wave (BCW_ms), which originates in the pulmonary microvasculature and is partially transmitted into the PT. This study tested the hypothesis that midsystolic augmentation of DA blood flow was related to transmission of the PA BCW_ms into the DA. DA, PT, and PA WI analysis was performed in eight anesthetized late-gestation fetal sheep instrumented with DA, PT, and left PA micromanometer catheters to measure pressure (P) and transit-time flow probes to obtain blood velocity (U). In a subgroup (n = 5), the main PA was briefly occluded to abolish wave transmission from the lungs. WI was calculated as the product of P and U rates of change. PA and PT WI profiles both contained a prominent BCW_ms, 5-fold larger in the PA (P < 0.005), which increased P but decreased U. By contrast, the DA WI profile demonstrated a large midsystolic forward-running compression wave (FCW_ms), which increased DA P and U, and occurred 5 ms after PA BCW_ms. Furthermore, both DA FCW_ms and PT BCW_ms were abolished by main PA occlusion. These results suggest that the fetal PA BCW_ms undergoes retrograde transmission into the PT as a BCW_ms, but antegrade transmission into the DA as a FCW_ms that augments midsystolic DA flow.

ductus arteriosus blood flow; ductus arteriosus blood pressure; fetal central hemodynamics