A Unified Methodology for Heartbeats Detection in Seismocardiogram and Ballistocardiogram Signals

Bed sensor ballistocardiogram for non-invasive detection of atrial fibrillation: a comprehensive clinical study

Objective.Atrial fibrillation (AFib) is a common cardiac arrhythmia associated with high morbidity and mortality, making early detection and continuous monitoring essential to prevent complications like stroke. This study explores the potential of using a ballistocardiogram (BCG) based bed sensor for the detection of AFib.Approach.We conducted a comprehensive clinical study with night hospital recordings from 116 patients, divided into 72 training and 44 test subjects. The study employs established methods such as autocorrelation to identify AFib from BCG signals. Spot and continuous Holter ECG were used as reference methods for AFib detection against which BCG rhythm classifications were compared.Results.Our findings demonstrate the potential of BCG-based AFib detection, achieving 94% accuracy on the training set using a rule-based method. Furthermore, the machine learning model trained with the training set achieved an AUROC score of 97% on the test set.Significance.This innovative approach shows promise for accurate, non-invasive, and continuous monitoring of AFib, contributing to improved patient care and outcomes, particularly in the context of home-based or hospital settings.

Unobstructive Heartbeat Monitoring of Sleeping Infants and Young Children Using Sheet-Type PVDF Sensors

Techniques for noninvasively acquiring the vital information of infants and young children are considered very useful in the fields of healthcare and medical care. An unobstructive measurement method for sleeping infants and young children under the age of 6 years using a sheet-type vital sensor with a polyvinylidene fluoride (PVDF) pressure-sensitive layer is demonstrated. The signal filter conditions to obtain the ballistocardiogram (BCG) and phonocardiogram (PCG) are discussed from the waveform data of infants and young children. The difference in signal processing conditions was caused by the physique of the infants and young children. The peak-to-peak interval (PPI) extracted from the BCG or PCG during sleep showed an extremely high correlation with the R-to-R interval (RRI) extracted from the electrocardiogram (ECG). The vital changes until awakening in infants monitored using a sheet sensor were also investigated. In infants under one year of age that awakened spontaneously, the distinctive vital changes during awakening were observed. Understanding the changes in the heartbeat and respiration signs of infants and young children during sleep is essential for improving the accuracy of abnormality detection by unobstructive sensors.

Precordial Vibrations: A Review of Wearable Systems, Signal Processing Techniques, and Main Applications

Recently, the ever-growing interest in the continuous monitoring of heart function in out-of-laboratory settings for an early diagnosis of cardiovascular diseases has led to the investigation of innovative methods for cardiac monitoring. Among others, wearables recording seismic waves induced on the chest surface by the mechanical activity of the heart are becoming popular. For what concerns wearable-based methods, cardiac vibrations can be recorded from the thorax in the form of acceleration, angular velocity, and/or displacement by means of accelerometers, gyroscopes, and fiber optic sensors, respectively. The present paper reviews the currently available wearables for measuring precordial vibrations. The focus is on sensor technology and signal processing techniques for the extraction of the parameters of interest. Lastly, the explored application scenarios and experimental protocols with the relative influencing factors are discussed for each technique. The goal is to delve into these three fundamental aspects (i.e., wearable system, signal processing, and application scenario), which are mutually interrelated, to give a holistic view of the whole process, beyond the sensor aspect alone. The reader can gain a more complete picture of this context without disregarding any of these 3 aspects.