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.