Electrocardiography Assessment of Sympatico–Vagal Balance during Resting and Pain Using the Texas Instruments ADS1299

Figures

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  Figure 1. Demonstration of the experimental protocol and representative HRV characteristics from ECG signals. (A): Schematic drawing of the combined two 8-channel ADS1299 systems and the ECG electrodes positions. (B): Schematic drawing of the tests at the baseline/resting (top panel) and the tonic pain/cold pressor (bottom panel) conditions. (C): Standard ECG signals (top panel) and the calculated HRV behavior (bottom panels) in time (left panel) and frequency (right panel) domains.

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  Figure 2. (A): A representative example of the raw and the filtered ECG signals. Data are voltage differences between the left and right arm (VL − VR). (B): The voltage components in the X-, Y-, and Z- axis in the vectorcardiography system, Vx, Vy, and Vz, and the voltage differences of (VL − VR), (VF − VC), and (VB − VC). VR, VL, VF, and VB are recordings on the right arm, left arm, left leg, and back in the Wilson system, and VC = (VR + VL + VF)/3. The components Vx, Vy, and Vz, were converted from the datasets in panel A. Scatters are the detected p-waves, QRS complexes, and T-waves.

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  Figure 3. A single representative example of the calculated heart rate variability (HRV), deceleration capacity of heart rate (DC), and periodic repolarization dynamics (PRD). (A): Vx component of the ECG signals with detected QRS complexes (red scatters) and T-waves (blue scatters and the yellow box). (B): Heartbeat (RR) intervals change during the experimental period. (C): Spectral analysis in the frequency domain of the RR interval data during resting and cold pressor test. The low-frequency power (0.04–0.15 Hz) and high-frequency power (0.15–0.40 Hz) were assessed by integrating the power spectral density curves. (D): Deceleration-related phase-rectified signal averaging curves of the heartbeat (RR) intervals during resting and cold pressor tests. The DC of heart rate was calculated from phase-rectified signal averaging curves of the RR intervals at index points of 0, 1, −1, and −2. (E): dT° angle change over time before and after low-pass filtering. (F): Phase-rectified signal averaging curves of the dT° angle during resting and cold pressor tests. The magnitude of the oscillations is quantified using PRD, which is a measure of the amplitude of the central part of the phase-rectified…