Background: Heart rate variability (HRV) is a physiological variation of intervals between consecutive heartbeats that reflects the activity of the autonomic nervous system. This parameter is traditionally evaluated based on electrocardiograms (ECG signals). Because seismocardiography (SCG) registers the cardiac mechanical activity, it may be used in HRV analysis and the evaluation of valvular heart diseases (VHDs) simultaneously.
Aims: To compare the time and frequency domain HRV indices were obtained from seismocardiograms (SCG signals) in healthy volunteers and patients with valvular heart diseases.
Methods: We use two publicly available datasets that contain simultaneous recordings of electrocardiograms and seismocardiograms: Combined measurement of ECG, Breathing and Seismocardiograms (CEBS) publicly available on PhysioNet.org and "An Open-access Database for the Evaluation of Cardio-mechanical Signals from Patients with Valvular Heart Diseases”. The heartbeats in ECG were detected with the Pan-Tompkins algorithm and then, the heartbeats in SCG signals were detected as the local maxima close to the QRS complexes in ECG signals. The HRV analysis was carried out according to the current recommendations and included the following indices: AVNN, SDNN, RMSSD, pNN50 (in time domain), VLF, LF, HF, and LF/HF (in frequency domain).
Results: HRV indices of VHD patients were significantly different than those obtained from healthy volunteers for the level of significance of 0.05, except for AVNN (p-value of 0.9283), VLF (p-value of 0.7313), and LF (p-value of 0.3083).
Conclusion: HRV indices derived from SCG signals in VHD patients are valid and are significantly different from those in healthy volunteers, except AVNN, VLF, and LF.