Affiliations: Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, Korea
Note: [] Corresponding author: Sang Joon Lee, Center for Biofluid and Biomimic Research, Department of Mechanical Engineering, Pohang University of Science and Technology, San 27, Hyoja-dong, Namgu, Pohang, Gyeongbuk, 790-784, South Korea. Tel.: +82 54 279 2169; Fax: +82 54 279 3199; E-mail: sjlee@postech.ac.kr
Abstract: Pulsatile blood flows are easily found in the vessels of living organisms. Under pulsatile flow conditions, red blood cells (RBCs) are aggregated and dispersed repetitively. The phenomenon of RBC aggregation is an influential factor in hemorheological and hemodynamic properties. This study aims to investigate the relationship between velocity profile and RBC aggregation in pulsatile blood flows. A rat extracorporeal bypass model was adopted to generate a real pulsatile flow without changing the rheological properties. To check the stability of the experimental model, variations of the hemodynamic parameters were measured consecutively for 2 h. Ultrasound speckle images of the blood flow in the extracorporeal bypass loop were acquired using a 35-MHz ultrasound scanner. The velocity fields were measured by the speckle image velocimetry (SIV) method, in which the cross-correlation algorithm is applied to the speckle images. In addition, the RBC aggregation was estimated by analyzing the echogenicity distribution of the speckle images. The shape of the velocity profile was cyclically varied according to the cardiac cycle. This variation may be closely related to the variation of the echogenicity distribution in pulsatile flows. The simultaneous measurement of velocity and RBC aggregation would be useful for understanding the effects of the hemorheological features on the hemodynamic characteristics of pulsatile blood flows.
Keywords: Echogenicity, pulsatile blood flow, rat extracorporeal bypass loop, red blood cell (RBC), RBC aggregation, speckle image velocimetry, velocity profile
