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Mechanobiological Evidence for the Control of Neutrophil Activity by Fluid Shear Stress
Published in Jiro Nagatomi, Eno Essien Ebong, Mechanobiology Handbook, 2018
Hainsworth Y. Shin, Xiaoyan Zhang, Ayako Makino, Geert W. Schmid-Schönbein
In the macrocirculation, blood pressure, flow, and wall stretch are pulsatile as a result of the cyclical pumping of the heart. Heart rates in humans during resting conditions are on average 60–80 beats/min (frequency of 1–1.2 Hz); physical activity and pathological conditions are associated with acute and/or chronic elevations in these values up to 200 beats/min (Guyton and Hall, 1996). In the microcirculation (e.g., capillaries, postcapillary venules), as well as in most of the venous system, blood flow and pressure are nearly steady since pulsation pressure amplitudes of the heart are reduced by the viscous energy dissipation in the microvasculature due to the dramatic increase in total cross-sectional area of the microcirculation to fluid transport as well as by the compliance of the blood vessels that become more thin-walled with lower content of collagen, elastin, and smooth muscle toward the microcirculation(Guyton and Hall, 1996). Pulsatile flow resulting from heart and skeletal muscle activity, however, has been documented for the microvasculature and in veins, particularly in the lower limbs, where venous valves ensure forward transport of blood volume back to the heart (Intaglietta et al., 1971; Lipowsky et al., 1978; Guyton and Hall, 1996; Sherwood, 2001).
in vitro Conditioning of Engineered Tissues
Published in Claudio Migliaresi, Antonella Motta, Scaffolds for Tissue Engineering, 2014
Aaron S. Goldstein, Patrick Thayer
Perfusion bioreactors have also been used to develop cardiac neo-tissues. In particular, pulsatile flow mechanically stimulates cardiomyocytes, while convection improves the delivery of nutrients and oxygen. For example, Kofidis et al.59 showed that pulsatile perfusion (100 ml/h, 2 Hz) increased cardiomyocyte viability throughout three-dimensional scaffolds compared with nonperfused scaffolds. In another study, Brown et al.60 demonstrated that pulsatile flow (1 Hz) conditioning resulted in neo-tissues with a lower excitation threshold, higher capture rate, and higher contraction amplitude than statically cultured neo-tissues.
Biomechanics in Cardiac Development Using 4D Light-Sheet Imaging
Published in Juhyun Lee, Sharon Gerecht, Hanjoong Jo, Tzung Hsiai, Modern Mechanobiology, 2021
Victoria Messerschmidt, Juhyun Lee
Fully developed Poiseuille blood flow seldom occurs in the arterial system in the presence of non-Newtonian properties of blood flow, in which the dynamic viscosity (µ) is not constant. The short distance between branches in response to pulsatile flow prevents fully developed flow. For these reasons, disturbed flow, including oscillatory flow, preferentially and geometrically occurs in the lateral wall of a branching point of the blood vessels or between two ridges in cardiac trabeculae during development (Figs. 8.1C and 8.2).
Pulsatile flow of thixotropic blood in artery under external body acceleration
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Louiza Cheffar, Abdelhakim Benslimane, Djamel Sadaoui, Adel Benchabane, Karim Bekkour
In most cases, arteries are assumed to be immobile, i.e. under normal physiological conditions. In this case, blood flow is driven by a biological pump: the heart producing a pulsatile pressure gradient in the cardiovascular system (Shit and Roy 2011). However, this excludes other important situations that occur in daily human life, in which the human body is subjected to external body acceleration, e.g. running, driving a vehicle, traveling in an airplane. A long exposure of body to such acceleration in time can leads to many health problems namely: increase in pulse rate, abdominal pain, venous pooling of blood in the extremities (Frolov et al. 2018). To this end, several researchers (Sud et al. 1983; Misra and Sahu 1988; Srivastava et al. 1994; Massoudi and Phuoc 2008) focused their studies on understanding blood flow in arteries under periodic body acceleration.
Structure and motion design of a mock circulatory test rig
Published in Journal of Medical Engineering & Technology, 2018
Yuhui Shi, Theodosios Korakianitis, Zhongjian Li, Yubing Shi
Three pressure transducers and two flow-rate transducers are installed in each loop, to measure the pressure in the atrium, the ventricle and the main artery, and the flow rates in the artery and the vein. The operating range of the pressure transducers is chosen as , in case there may be temporary pressure overload in the system. Electromagnetic type or ultrasound type flow transducers are good candidates for the measurement of the pulsatile flow in the systematic artery and the pulmonary artery positions. Considering that the normal cardiac output is and it may raise to about in the maximum exercise condition [39], the operating range of the flow transducer can be set as . Flows in the simulated systematic and pulmonary vein positions are much steady, so the rotameters can be used in these locations to save the expense.
Quantification of error between the heartbeat intervals measured form photoplethysmogram and electrocardiogram by synchronisation
Published in Journal of Medical Engineering & Technology, 2018
Srinivas Kuntamalla, Ram Gopal Reddy Lekkala
The pulsatile flow of blood in the arteries is produced through the circulatory pumping action of the heart by means of ventricular systole and diastole. The ventricular systole is produced by the contraction of left ventricular myocardium during its electrical excitation through Purkinje fibres, which are recorded as R-peaks in ECG. The causal relationship between the R-peaks in ECG and the systolic peaks in PPG representing the systolic phase in pulsatile blood flow in arteries is a well-known physiologically established fact [9]. It, therefore, obviates the need for any statistical analysis to explore the relationship between them. The peak to peak intervals in PPG and R–R intervals in ECG, both measure the same physiological parameter, the heart beat interval, which can be seen in Figure 1.