TY - JOUR
T1 - Nature of flow acceleration into a finite-sized orifice
T2 - Steady and pulsatile flow studies on the flow convergence region using simultaneous ultrasound Doppler flow mapping and laser Doppler velocimetry
AU - Shandas, Robin
AU - Gharib, Morteza
AU - Sahn, David J.
N1 - Funding Information:
From the Children's Hospital, Denver, Colorado; *California Institute of Technology, Pasadena, California; and \]Oregon Health Sciences University, Portland, Oregon. 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. Manuscript received May 31, 1994; revised manuscript received November 28, 1994, accepted December 5, 1994. Address for correspondence: Dr. Robin Shandas, Denver Children's Hospital B100, 1056 East 19th Avenue, Denver, Colorado 80218-1088.
PY - 1995/4
Y1 - 1995/4
N2 - 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 cm2). 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 cm2). 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.
AB - 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 cm2). 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 cm2). 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.
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U2 - 10.1016/0735-1097(94)00533-V
DO - 10.1016/0735-1097(94)00533-V
M3 - Article
C2 - 7897135
AN - SCOPUS:0028951039
SN - 0735-1097
VL - 25
SP - 1199
EP - 1212
JO - Journal of the American College of Cardiology
JF - Journal of the American College of Cardiology
IS - 5
ER -