Abstract:
A simple nonlinear beat-to-beat model of the human cardiovascular system has been
studied. The model, introduced by DeBoer et al. was a simplified linearized version.
We present a modified model which allows to investigate the nonlinear dynamics of
the cardiovascular system. We found that an increase in the -sympathetic gain, via
a Hopf bifurcation, leads to sustained oscillations both in heart rate and blood pressure
variables at about 0.1 Hz (Mayer waves). Similar oscillations were observed when increasing
the -sympathetic gain or decreasing the vagal gain. Further changes of the gains,
even beyond reasonable physiological values, did not reveal another bifurcation. The
dynamics observed were thus either fixed point or limit cycle. Introducing respiration
into the model showed entrainment between the respiration frequency and the Mayer
waves.
Keywords:
Cardiovascular System - Mathematical Model - Bifurcation
