Biorheology - Volume 58, issue 1-2

Authors: Armstrong, Matthew | Milner, Erin | Nguyen, Chi | Corrigan, Trevor | Lee, Yu-Fan

Article Type: Research Article

Abstract: BACKGROUND: Human blood is a thixo-elasto-visco-plastic (TEVP) material that exhibits unique fluctuations in mechanical properties based on physiology, and shear rate. We demonstrate new visual tools to help visualize and characterize these varied mechanical properties. OBJECTIVE: Our objective is to demonstrate contemporary visual and numerical tools to help visualize and characterize the varied mechanical properties of human blood. METHODS: Using the ARESG2 strain-controlled rheometer with double wall couette geometry and eight human blood donors, with lab test results, elastic and viscous properties are investigated using Series of Physical Processes (SPP) and MITLaos to both analyze and …visualize the mechanical signatures of the blood. RESULTS: Variations of mechanical properties are shown via SPP generated Cole-Cole plots and MITLaos analysis. These variations are a function of physiological properties of blood on the day of the blood draw based on hematocrit, fibrinogen, cholesterol, triglycerides, and a host of other proteins and constituents. Each rheological experiment with blood is replicated with an analogous experiments with 0.04 wt% xanthan in glycerol, and water to demonstrate that the mechanical properties of the human blood, and its rheological signatures are unique to human blood. CONCLUSIONS: Human blood is proven to be a TEVP material, as shown on a series of Cole-Cole plots for eight different donors, at two different frequency and strain amplitude combinations. Variations in Cole-Cole plots for each donor are shown. MITLaos average mechanical properties are calculated and shown. Aggregated elastic and viscous projections and a Cole-Cole plot is shown for Donors 1–8, along with 95% confidence interval. Show more

Keywords: Human blood, hemorheology, triangle ramp, large amplitude oscillatory shear

DOI: 10.3233/BIR-201007

Citation: Biorheology, vol. 58, no. 1-2, pp. 1-26, 2021

Authors: Chen, Ying | Yang, Yunmei | Tan, Wenchang | Fu, Liqin | Deng, Xiaoyan | Xing, Yubin

Article Type: Research Article

Abstract: BACKGROUND: Heart failure (HF) is a common disease globally. Ventricular assist devices (VADs) are widely used to treat HF. In contrast to the natural heart, different VADs generate different blood flow waves in the aorta. OBJECTIVE: To explore whether the different inflow rate waveforms from the ascending aorta generate far-reaching hemodynamic influences on the human aortic arch. METHODS: An aortic geometric model was reconstructed based on computed tomography data of a patient with HF. A total of five numerical simulations were conducted, including a case with the inflow rate waveforms from the ascending aorta with normal …physiological conditions, two HF, and two with typical VAD support. The hemodynamic parameters, wall shear stress (WSS), oscillatory shear index (OSI), relative residence time (RRT), and the strength of the helical flow, were calculated. RESULTS: In contrast to the natural heart, numerical simulations showed that HF decreased WSS and induced higher OSI and RRT. Moreover, HF weakened helical flow strength. Pulsatile flow VADs that elevated the WSS, induced some helical flow, while continuous flow VADs could not. CONCLUSIONS: HF leads to an adverse hemodynamic environment by decreasing WSS and reducing the helical flow strength. Based upon hemodynamic effects, pulsatile flow VADs may be more advantageous than continuous flow VADs. Thus, pulsatile flow VADs may be a better option for patients with HF. Show more

Keywords: Heart failure, wall shear stress, continuous flow, pulsatile flow, helical flow

DOI: 10.3233/BIR-201009

Citation: Biorheology, vol. 58, no. 1-2, pp. 27-38, 2021

Authors: Zhu, Xiaotong | Zhang, Keying | He, Li | Liao, Fuyuan | Ren, Yuanchun | Jan, Yih-Kuen

Article Type: Research Article

Abstract: BACKGROUND: Local vibration has shown promise in improving skin blood flow and wound healing. However, the underlying mechanism of local vibration as a preconditioning intervention to alter plantar skin blood flow after walking is unclear. OBJECTIVE: The objective was to use wavelet analysis of skin blood flow oscillations to investigate the effect of preconditioning local vibration on plantar tissues after walking. METHODS: A double-blind, repeated measures design was tested in 10 healthy participants. The protocol included 10-min baseline, 10-min local vibrations (100 Hz or sham), 10-min walking, and 10-min recovery periods. Skin blood flow was measured …over the first metatarsal head of the right foot during the baseline and recovery periods. Wavelet amplitudes after walking were expressed as the ratio of the wavelet amplitude before walking. RESULTS: The results showed the significant difference in the metabolic (vibration 10.06 ± 1.97, sham 5.78 ± 1.53, p < 0.01) and neurogenic (vibration 7.45 ± 1.54, sham 4.78 ± 1.22, p < 0.01) controls. There were no significant differences in the myogenic, respiratory and cardiac controls between the preconditioning local vibration and sham conditions. CONCLUSIONS: Our results showed that preconditioning local vibration altered the normalization rates of plantar skin blood flow after walking by stimulating the metabolic and neurogenic controls. Show more

Keywords: Control mechanism, skin blood flow, vibration therapy, wavelet analysis

DOI: 10.3233/BIR-201011

Citation: Biorheology, vol. 58, no. 1-2, pp. 39-49, 2021

Authors: Turgut, Alper | Yalçin, Özlem

Article Type: Research Article

Abstract: BACKGROUND: Measurement of abnormal Red Blood Cell (RBC) deformability is a main indicator of Sickle Cell Anemia (SCA) and requires standardized quantification methods. Ektacytometry is commonly used to estimate the fraction of Sickled Cells (SCs) by measuring the deformability of RBCs from laser diffraction patterns under varying shear stress. In addition to estimations from model comparisons, use of maximum Elongation Index differences (ΔEI max ) at different laser intensity levels was recently proposed for the estimation of SC fractions. OBJECTIVE: Implement a convolutional neural network to accurately estimate rigid-cell fraction and RBC concentration from laser diffraction patterns without …using a theoretical model and eliminating the ektacytometer dependency for deformability measurements. METHODS: RBCs were collected from control patients. Rigid-cell fraction experiments were performed using varying concentrations of glutaraldehyde. Serial dilutions were used for varying the concentration of RBC. A convolutional neural network was constructed using Python and TensorFlow. RESULTS and CONCLUSIONS: Measurements and model predictions show that a linear relationship between ΔEI max and rigid-cell fraction exists only for rigid-cell fractions less than 0.2. The proposed neural network architecture can be used successfully for both RBC concentration and rigid-cell fraction estimations without a need for a theoretical model. Show more

Keywords: Ektacytometry, RBC, neural network, deep learning

DOI: 10.3233/BIR-201016

Citation: Biorheology, vol. 58, no. 1-2, pp. 51-60, 2021