Variable resonance and chaos in collapsible blood vessels

A vessel segment was terminated with a section of artery subjected to near zero transmural pressure. The sinusoidal frequency response was determined by solving the resulting nonlinear differential equations. Two phenomena were observed. The resonant frequency could be tuned by varying the mean transmural pressure. Aperiodic flow waveforms occurred (chaos) for large amplitude of the driving sinusoidal pressure. These effects were evident when the cross-sectional shape is altered during collapse.