Abstract
It is considered that RR interval (heart beat interval) and blood pressure fluctuate under the influence of circulation control by autonomic nerves and pulse wave propagation. Based on the above, we combined the model of a circulation control and the simulation of pulse wave propagation taking FSI effect into consideration, and constructed a coupling model capable of calculating RR interval and blood pressure value according to the state of autonomic nerves. After that, we confirmed whether the coupling model can reproduce the relation between RR interval and sleepiness observed experimentally. In the beginning, we investigated a factor which has an influence on the formation of pulse waveforms. As a result, the flow velocity distribution which determines viscous term in the Navier-Stokes equation has a great effect on formation of pulse waveforms. On the other hand, viscoelasticity of blood vessel walls has few effects. Next, considering the interaction between circulation control and pulse wave propagation, we constructed the coupling model. In this coupling model, we reflected the change in the stiffness of blood vessels. This is because blood vessels become narrower and the stiffness increases, if sympathetic nerves become predominant. Comparing the results of calculation by the coupling model and only the model of a circulation control, it was found that in the coupling model we successfully reflected the action of resistance in a blood vessel.
