Power Doppler ultrasound evaluation of the shear rate and shear stress dependences of red blood cell aggregation

Previous in vitro studies of blood flow in small glass tubes have shown that red blood cells exhibit significant erratic deviations in the radial position in the laminar flow regime. The purpose of the present study was to assess the magnitude of this variability and that of velocity in vivo and the effect of red blood cell aggregation and shear rate upon them. With the use of a gated image intensifier and fluorescently labeled red blood cells in tracer quantities, we obtained multiple measurements of red blood cell radial and longitudinal positions at time intervals as short as 5 ms within single venous microvessels (diameter range 45–75 μm) of the rat spinotrapezius muscle. For nonaggregating red blood cells in the velocity range of 0.3–14 mm/s, the mean coefficient of variation of velocity was 16.9 ± 10.5% and the SD of the radial position was 1.98 ± 0.98 μm. Both quantities were inversely related to shear rate, and the former was significantly lowered on induction of red blood cell aggregation by the addition of Dextran 500 to the blood. The shear-induced random movements observed in this study may increase the radial transport of particles and solutes within the bloodstream by orders of magnitude.

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Measurement of the temperature-dependent threshold shear-stress of red blood cell aggregation

Review of Scientific Instruments ◽

10.1063/1.3223534 ◽

2009 ◽

Vol 80 (9) ◽

pp. 096101 ◽

Cited By ~ 3

Author(s):

Hyun-Jung Lim ◽

Jeong-Hun Nam ◽

Yong-Jin Lee ◽

Sehyun Shin

Keyword(s):

Shear Stress ◽

Blood Cell ◽

Red Blood Cell ◽

Cell Aggregation ◽

Temperature Dependent ◽

Red Blood Cell Aggregation ◽

Blood Cell Aggregation

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Numerical simulation of spatiotemporal red blood cell aggregation under sinusoidal pulsatile flow

Scientific Reports ◽

10.1038/s41598-021-89286-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Cheong-Ah Lee ◽

Dong-Guk Paeng

Keyword(s):

Shear Rate ◽

Blood Cell ◽

Red Blood Cell ◽

Pulsatile Flow ◽

Cell Aggregation ◽

Spatiotemporal Variation ◽

Shear Rates ◽

Red Blood Cell Aggregation ◽

Axial Shear ◽

Rbc Aggregation

AbstractPrevious studies on red blood cell (RBC) aggregation have elucidated the inverse relationship between shear rate and RBC aggregation under Poiseuille flow. However, the local parabolic rouleaux pattern in the arterial flow observed in ultrasonic imaging cannot be explained by shear rate alone. A quantitative approach is required to analyze the spatiotemporal variation in arterial pulsatile flow and the resulting RBC aggregation. In this work, a 2D RBC model was used to simulate RBC motion driven by interactional and hydrodynamic forces based on the depletion theory of the RBC mechanism. We focused on the interaction between the spatial distribution of shear rate and the dynamic motion of RBC aggregation under sinusoidal pulsatile flow. We introduced two components of shear rate, namely, the radial and axial shear rates, to understand the effect of sinusoidal pulsatile flow on RBC aggregation. The simulation results demonstrated that specific ranges of the axial shear rate and its ratio with radial shear rate strongly affected local RBC aggregation and parabolic rouleaux formation. These findings are important, as they indicate that the spatiotemporal variation in shear rate has a crucial role in the aggregate formation and local parabolic rouleaux under pulsatile flow.

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