| Computational fluid dynamic analysis of flow velocity waveform notching in umbilical arteries. | |
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MedLine Citation:
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PMID: 20926769 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Umbilical artery Doppler velocimetry waveform notching has long been associated with umbilical cord abnormalities, such as distortion, torsion, and/or compression (i.e., constriction). The physical mechanism by which the notching occurs has not been elucidated. Flow velocity waveforms (FVWs) from two-dimensional pulsatile flows in a constricted channel approximating a compressed umbilical cord are analyzed, leading to a clear relationship between the notching and the constriction. Two flows with an asymmetric, semi-elliptical constriction are computed using a stabilized finite-element method. In one case, the constriction blocks 75% of the flow passage, and in the other the constriction blocks 85%. Channel width and prescribed flow rates at the channel inflow are consistent with typical cord diameters and flow rates reported in the literature. Computational results indicate that waveform notching is caused by flow separation induced by the constriction, giving rise to a vortex (core) wave and associated eddies. Notching in FVWs based on centerline velocity (centerline FVW) is directly related to the passage of an eddy over the point of measurement on the centerline. Notching in FVWs based on maximum cross-sectional velocity (envelope FVW) is directly related to acceleration and deceleration of the fluid along the vortex wave. Results show that notching in envelope FVW is not present in flows with less than a 75% constriction. Furthermore, notching disappears as the vortex wave is attenuated at distances downstream of the constriction. In the flows with 75 and 85% constriction, notching of the envelope FVW disappears at ∼3.8 and ∼4.3 cm (respectively) downstream of the constriction. These results are of significant medical importance, given that envelope FVW is typically measured by commercial Doppler systems. |
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Authors:
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Andrés E Tejada-Martínez; Christian J Borberg; Resmi Venugopal; Carlos Carballo; Wilfrido A Moreno; Rubén A Quintero |
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Publication Detail:
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Type: Journal Article Date: 2010-10-06 |
Journal Detail:
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Title: American journal of physiology. Regulatory, integrative and comparative physiology Volume: 300 ISSN: 1522-1490 ISO Abbreviation: Am. J. Physiol. Regul. Integr. Comp. Physiol. Publication Date: 2011 Jan |
Date Detail:
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Created Date: 2010-12-24 Completed Date: 2011-01-20 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100901230 Medline TA: Am J Physiol Regul Integr Comp Physiol Country: United States |
Other Details:
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Languages: eng Pagination: R76-84 Citation Subset: IM |
Affiliation:
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Department of Civil and Environmental Engineering, University of South Florida, Tampa, Florida, USA. aetejada@usf.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Algorithms Blood Flow Velocity / physiology* Blood Viscosity / physiology Humans Hydrodynamics* Models, Biological* Regional Blood Flow / physiology Umbilical Arteries / physiology* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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