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Nature of flow acceleration into a finite-sized orifice: Steady and pulsatile flow studies on the flow convergence region using simultaneous ultrasound Doppler flow mapping and laser Doppler velocimetry

Shandas, Robin and Gharib, Morteza and Sahn, David J. (1995) Nature of flow acceleration into a finite-sized orifice: Steady and pulsatile flow studies on the flow convergence region using simultaneous ultrasound Doppler flow mapping and laser Doppler velocimetry. Journal of the American College of Cardiology, 25 (5). pp. 1199-1212. ISSN 0735-1097. https://resolver.caltech.edu/CaltechAUTHORS:20130913-093052423

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Abstract

Objectives. This study investigated the proximal centerline flow convergence region simultaneously by both color Doppler and laser Doppler velocimetry. Background. Although numerous investigations have been performed to test the flow convergence method, to our knowledge there has yet been no experimental study using reference standard velocimetric techniques to define precisely the hydrodynamic factors involved in the accelerating flow region during steady and pulsatile flow. Methods. Using an in vitro model that allows velocity measurements by laser Doppler velocimetry with simultaneous comparison with color Doppler results, we studied the centerline flow acceleration region proximal to orifices of various sizes (0.08 to 2.0 cm^2). Results. Agreement between theory and experimental velocities was good for large flow rates through small orifices only, and only at distances >1.2 cm from the orifice. Changing the orifice shape from circular to slitlike produced no significant changes in velocity profiles. Constraining the proximal side walls caused a significant increase in proximal velocities at distances >0.7 cm for the largest orifice only (2.0 cm^2). Calculated flow rates agreed well with actual flow rates, with functional dependence on proximal distance and orifice size. Velocity profiles for pulsatile flow were similar to steady state flow profiles and could be integrated to calculate stroke volumes, which followed actual flow volumes well, although with general overestimation (y = 1.22x + 0.164, r = 0.92), most likely due to the use of all available proximal velocities. Conclusions. The accelerating proximal flow region responds to several hydrodynamic factors that can affect flow quantitation using the flow convergence method in the clinical situation.


Item Type:Article
Related URLs:
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http://dx.doi.org/10.1016/0735-1097(94)00533-VDOIArticle
http://www.sciencedirect.com/science/article/pii/073510979400533VPublisherArticle
Additional Information:© 1995 by the American College of Cardiology. Manuscript received May 31, 1994; revised manuscript received November 28, 1994, accepted December 5, 1994. This study was funded in part by Grant R01-HL-43287 from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland. We are grateful to Baron Thomas, BS for building the flow phantom and flow setup. We also thank Dr. Takahiro Shiota for generous help and Patricia Gallagher for secretarial help and support during PhD thesis work by Dr. Shandas at University of California--San Diego Pediatric Cardiology Department.
Group:GALCIT
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Funding AgencyGrant Number
NIH National Heart, Lung, and Blood InstituteR01-HL-43287
Issue or Number:5
Record Number:CaltechAUTHORS:20130913-093052423
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130913-093052423
Official Citation:Robin Shandas, Morteza Gharib, David J. Sahn, Nature of flow acceleration into a finite-sized orifice: Steady and pulsatile flow studies on the flow convergence region using simultaneous ultrasound Doppler flow mapping and laser Doppler velocimetry, Journal of the American College of Cardiology, Volume 25, Issue 5, April 1995, Pages 1199-1212, ISSN 0735-1097, http://dx.doi.org/10.1016/0735-1097(94)00533-V. (http://www.sciencedirect.com/science/article/pii/073510979400533V)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41312
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Sep 2013 20:03
Last Modified:03 Oct 2019 05:47

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