Consideration of the Role of Vasomotion-Induced Flowmotion on Microvascular Blood Flow

The term "flowmotion" describes the temporally dynamic changes in microvascular blood flow or blood velocity accompanying spontaneous time-varying changes in arteriole diameters, a process termed "vasomotion." Flowmotion is readily measurable in human skin using laser Doppler flowmetry and has been studied empirically to characterize its spectral features and disease-related changes in amplitude and frequency. However, there is a lack of clarity regarding the effect on blood flow within arterioles that exhibit these time-varying diameter changes. Thus, the goals of the present study were to (1) investigate the effects of vasomotion on blood flow within arterioles using simulated sinusoidal and trapezoidal vasomotion patterns and (2) determine the difference in blood flow effects between these two vasomotion patterns.  Methods: The sinusoidal diameter was expressed as [Formula: see text] where [Formula: see text] is the peak-to-peak vasomotion amplitude and [Formula: see text] is the period of oscillation. For the trapezoidal case, the diameter was expressed in terms of the Fourier series for a periodic trapezoidal waveform. The impacts of vasomotion as a function of the amplitude a were determined analytically for the sinusoidal case and numerically for both cases.

Analysis indicates that sinusoidal and trapezoidal vasomotion are associated with an average blood flow that is greater than would be present in a vessel with a fixed diameter, and the trapezoidal pattern yields a greater increase than the sinusoidal pattern.

Analytic and numerical evaluations of sinusoidal and trapezoidal diameter variations revealed that the resultant flowmotion was associated with greater average blood flow, with the trapezoidal pattern being slightly more effective than the sinusoidal pattern. Although the impact of these dynamics on the functional aspects of the overall microvascular network, including microvascular exchange processes, was not considered in the present report, these aspects represent areas well warranted for future research.