Resumen:
Introduction: The Windkessel model simulates the radial pulse wave. When the aortic valve closes, instead of a pressure
decrease during diastole, there is an initial increase due to a resonant response. The aim of this study was to explain this
phenomenon based on the spectral analysis, and determine how it is affected by aging.
Methods: The Fourier spectrum of resting pressure wave was analysed in a healthy set of 49 young individuals (26.9±7.3 years)
and 51 adults (53.4±10.3 years). To explain the results, the Windkessel was considered a low-pass filter composed by distal
compliance Cd, aortic inertance L, and peripheral resistance Rp.
Results: The spectrum obtained showed a maximum amplitude between 3 and 4 Hz, evidencing resonant behavior in that
frequency range. Linear regression of diastolic pressure increases revealed that it depends mainly on the amplitude of the 3rd
harmonic of the spectrum (p<0.001), for normal heart rate values.
Conclusions: The arterial system resonates at a frequency close to 3.5 Hz, generating the oscillation responsible for the
diastolic pressure increase. The resonance frequency remains constant with age, however, the oscillation amplitude, related
to small distal artery compliance and endothelial dysfunction, decreases by more than 50%. The resonant configuration of
the arterial system results from an evolutionary development that allows diastolic pressure to be increased for approximately
300 ms, using the energy stored during systole. Spectral analysis allows the assessment of aging of the arterial system, and
could be useful in evaluating the effects of cardiometabolic diseases on small arteries.
