The effects of low heart rates on frequency domain carotid-radial transfer functions modeling

The transfer function was a common method to calculate central pressure. This paper was to investigate the effects of low heart rate on carotid-radial transfer function modeling. Sixty subjects aged 25-85 (66±13.60 years) were studied and divided into 3 heart rates groups (Group1: 45-55 beats/min, Group2: 55-65 beats/min, Group3: 65-75 beats/min). In our estimation, we established the frequency techniques based the transfer function with its harmonics varied from 1-4th to 1-10th. The accuracy of the transfer function was evaluated by the index MSD (mean square difference) between measured central pressure waveforms' amplitude and reconstructed waveforms from the transfer function. For the Group2 (55-65 beats/min), the transfer function fitting index MSD decreased from 4.30 to 0.72, as the transfer function harmonics varied from 1-4th to 1-10th. For Group3 (65-75 beats/min), the MSD changed from 3.22 to 0.53 as the transfer function harmonics varied from 1-4th to 1-10th. When for Group1 (45-55 beats/min), the MSD changed from 4.81 to 0.71 as the transfer function harmonics varied from 1-4th to 1-10th. In summary, it was indicated that among those low heart rates people, the 45-55 and 55-65 beats/min heart rates persons need 1-9th to 1-10th harmonic transfer functions, while the 65-75 beats/min heart rates persons could adapt 1-4th to 1-8th harmonic transfer functions. Among 45-75 beats/min patients, higher heart rates persons' reliance on 1-10th harmonic transfer functions decreased.