Experimental investigations have established that the stiffness of large arteries has a dependency on acute heart rate (HR) changes. However, possible underlying mechanisms inherent in this HR dependency have not been well established. This study aimed to explore a plausible viscoelastic mechanism by which HR exerts an influence on arterial stiffness. A multi-segment transmission line model of the human arterial tree incorporating fractional viscoelastic components in each segment was used to investigate the effect of varying fractional order parameter (α) of viscoelasticity on the dependence of aortic arch to femoral artery pulse wave velocity (afPWV) on HR. HR was varied from 60 to 100 beats per minute (bpm) at a fixed mean flow of 100 ml/s. PWV was calculated by intersecting tangent method (afPWVTan) and by phase velocity from the transfer function (afPWVTF) in the time and frequency domain, respectively. PWV was significantly and positively associated with HR for α ≥ 0.6; for α = 0.6, 0.8 and 1, HR-dependent changes in afPWVTan were 0.01 ± 0.02, 0.07 ± 0.04 and 0.22 ± 0.09 m/s per 5 bpm; HR-dependent changes in afPWVTF was 0.02 ± 0.01, 0.12 ± 0.00 and 0.34 ± 0.01 m/s per 5 bpm, respectively). This crosses the range of previous physiological studies where the dependence of PWV on HR was found to be between 0.08 and 0.10m/s per 5bpm. Therefore, viscoelasticity of the arterial wall could contribute to mechanisms through which large artery stiffness changes with changing HR. Physiological studies are required to confirm this mechanism.
- pulse wave velocity
- heart rate
- transmission line model
- Copyright © 2017, American Journal of Physiology-Heart and Circulatory Physiology