Can wavelet transform analysis of laser Doppler flowmetry characterize oscillations in human peripheral blood flow and endothelial activity?
Wavelet analysis of laser Doppler flowmetry can identify specific frequency oscillations in peripheral blood flow, demonstrating that endothelial activity is a rhythmic process around 0.01 Hz.
The wavelet transform technique, a time-frequency method with logarithmic frequency resolution, was used to analyze oscillations in human peripheral blood flow measured by laser Doppler flowmetry. The oscillations extended over a wide frequency scale and their periods varied in time. Within the frequency range studied, 0.0095-1.6 Hz, five characteristic oscillations were revealed, arising from both local and central regulatory mechanisms. After the insertion of endothelium-dependent and endothelium-independent vasodilators the spectra of blood flow markedly differed in the frequency interval 0.0095-0.02 Hz. In this way it was demonstrated that endothelial activity is a rhythmic process that contributes to oscillations in blood flow with a characteristic frequency of around 0.01 Hz. The study illustrates the potential of laser Doppler flowmetry combined with dynamical systems analysis for studies of both the micro- and macroscopic mechanisms of blood flow regulation in vivo.
Stefanovska et al. (Fri,) studied this question.