Patent ID: 8628476

Claim:
A blood vessel state evaluation device comprising: a storage unit for storing a circulatory system model in which a blood vessel located in a living body is divided into a plurality of zones and modeled, the circulatory system model including a shape value representing each of the plurality of zones; a first measurement unit, adapted for attachment to a first measurement site of the living body, for measuring a time waveform of a first biological signal; a second measurement unit, adapted for attachment to a second measurement site of the living body, for measuring a time waveform of a second biological signal in synchronization with the first measurement unit; a first calculating unit for calculating phase difference characteristics of actual measurement based on a phase difference on each frequency component between the first biological signal and the second biological signal, wherein the first calculating unit is configured to calculate the phase difference characteristics of actual measurement using a frequency component in which a coherence value, which is an index indicating a correlation at a frequency region, between the first biological signal and the second biological signal is higher than a threshold value defined in advance; a second calculating unit for calculating phase difference characteristics between a first transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the first measurement site and a second transfer function defined based on the circulatory system model in correspondence to a blood vessel passage to the second measurement site, the first transfer function and the second transfer function including an elasticity variable indicating a degree of elasticity of the blood vessel; and a search unit for determining an optimum elasticity variable by sequentially changing the elasticity variable from an initial value until the phase difference characteristics calculated by the second calculating unit substantially match the phase difference characteristics of actual measurement calculated by the first calculating unit, wherein the elasticity variable indicates a degree of arterial sclerosis of the blood vessel located in the living body.