The importance of viscoelasticity in arterial blood flow models

Abstract

The assumption of negligible viscoelastic response in arterial walls has been routinely made in the analysis of cardiovascular fluid dynamics, however, with incomplete justification. The present study was designed to explore this justification in depth. In a commonly used one-dimensional blood flow model, the viscoelastic properties of the thoracic aorta are mathematically modelled as an area pressure shift in the State Equation. From experimentally measured proximal pressure and velocity waveforms, distal waveforms are computed by the periodic method of characteristics for different levels of viscoelasticity and compared with those waveforms obtained from the same model having purely elastic arterial walls. The results indicate that viscoelasticities encountered physiologically do not discernibly affect the development of the pressure and velocity waveforms. Further, for stiffer vessel walls, the viscous wall component is even less important. It is concluded that for most practical purposes in single large artery models, the arterial walls may be considered to be purely elastic. The corresponding justification for multiple artery models or for smaller arteries has not been examined.