A textile-based wearable system for the prolonged assessment of cardiac mechanics in daily life

Seismocardiogram, SCG, can be detected over the 24 hours in ambulant subjects by a textile-based wearable system together with the electrocardiogram, ECG and respiration. In this pilot study we explored the possibility to derive 24 h profiles of cardiac time intervals, i.e. indexes of heart mechanical function, from the SCG recordings performed in daily life conditions by the above wearable system. Two healthy subjects were recruited for the study. They worn the system for 24 hours during a working day. From each recording, every 30 minutes the following parameters were derived from the ECG and SCG signals: RR interval, RRI, Pre-Ejection Period, PEP, Isovolumic Contraction Time, ICT, Left Ventricular Ejection Time, LVET, Isovolumic Relaxation Time, IRT. From the analysis it appears that 1) all parameters are characterized by a coefficient of variation in the same order of magnitude, and 2) 24 h LVET time profiles mirrors the long term RRI behavior. Common trends in PEP and ICT profiles were observed in one subject. This study indicates that indexes of cardiac mechanics can be derived from SCG recordings performed over the 24 hours. The obtained positive results encourage further studies to refine this methodology and confirm the present findings.