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This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: 297/2/R428    most recent 00174.2009v1 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 Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) 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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Dynamic characterization and hemodynamic effects of pulmonary waves in fetal lambs using cardiac extrasystoles and beat-by-beat wave intensity analysis

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 25 March 2009 ; accepted in final form 2 June 2009

Steady-state wave intensity (WI) analysis indicates that characteristic midsystolic falls in fetal pulmonary trunk (PT) and artery (PA) blood flow are due to an extremely large backward-running compression wave (BCW_ms) that 1) originates from the pulmonary microvasculature by a combination of cyclical pulmonary vasoconstriction and vascular reflection of the forward-running compression wave (FCW_is) associated with impulsive right ventricular ejection, and 2) is transmitted into the PT. However, no information is available about the dynamic properties of PA BCW_ms and its contribution to beat-to-beat regulation of pulmonary hemodynamics. Accordingly, beat-by-beat WI analysis was performed during brief increases in ventricular contractility accompanying an extrasystole (ES) in nine anesthetized late-gestation fetal sheep instrumented with PT and left PA micromanometer catheters to measure pressure (P) and transit-time flow probes to obtain blood velocity (U). WI was calculated as the product of P and U rates of change. At steady state, the magnitude of PA BCW_ms, and its associated P and U changes (P and U, respectively), were similar to those of FCW_is. The PA FCW_is and BCW_ms, and their accompanying P and U, were all transiently potentiated after an ES. Beat-by-beat PA FCW_is-BCW_ms wave area, P and U relationships were highly linear (R² 0.91) with slopes of 1.36–1.47 (P < 0.001), consistent with the presence of a vasoconstrictor component in PA BCW_ms. PA-PT BCW_ms area and P and U relationships were also linear (R² 0.77) with slopes of 0.23–0.64 (P < 0.001). These results indicate that the fetal PA BCW_ms contributes to beat-to-beat regulation of not only PA but also PT hemodynamics.

fetal pulmonary blood flow; fetal pulmonary blood pressure; post-extrasystolic potentiation

This article has been cited by other articles:

				J. J. Smolich, J. P. Mynard, and D. J. Penny Ductus arteriosus wave intensity analysis in fetal lambs: midsystolic ductal flow augmentation is due to antegrade pulmonary arterial wave transmission Am J Physiol Regulatory Integrative Comp Physiol, October 1, 2009; 297(4): R1171 - R1179. [Abstract] [Full Text] [PDF]