Quantification of Posture Induced Changes in Wearable Seismocardiogram Signals for Heart Failure Patients

Abstract

Our goal is to characterize the effects of posture-supine, seated, and standing-on the seismocardiogram (SCG) signal for patients with heart failure (HF). Posture can (1) distort the SCG signal, for example due to altering the body's mechanical vibration response, and (2) affect a person's cardiovascular physiology, for example due to changes in venous return. This work focuses on characterizing the former, such that in future studies we can use the SCG to assess physiological changes in patients with HF at home. Our team has developed a circular patch (7 cm in diameter) which, when placed on the sternum, simultaneously measures the electrocardiogram (ECG) along with SCG signals in the dorso-ventral and head-to-foot directions. We recruited six HF patients thus far for this ongoing study. Each subject was asked to lie down in a supine position on a patient bed for 1 minute followed by 1 minute in each of the seated and standing postures. A novel algorithm was implemented to compare distortion in the shape of the SCG signals in the supine and seated postures as compared to the standing upright posture. The frequency domain analysis of the SCG signals revealed presence of high energy in bands greater than 8 Hz for supine and seated postures. Based on the findings of this paper, features can be derived to correct for posture related changes in the measured SCG signals for accurate assessment of patients with HF at home.

Contactless seismocardiography via deep learning radars

“…As the reseach evolves, it would be very interesting to evaluate the system's accuracy in medical applications, which have already been verified with on-body SCG recordings. Such applications include detecting cardiovascular diseases (such coronary artery disease, ischemia, valvular or structural heart diseases, heart failure) [21,24,45,46,67] as well as long-term monitoring of patients with cardiovascular conditions (such as arrythmia) [20,38]. It would also be interesting to expand the system's capabilities so that it can capture SCG recordings from further away subjects as well as those who are moving around in their everyday environments.…”

Recent Advances in Seismocardiography

“…Subject motion and postural position were also shown to cause changes in SCG signals [7,75,88]. In an ongoing study, the effect of posture on the SCG signals was investigated for patients with heart failure (HF) [75]. The SCG signals were measured using a wearable unit in supine and seated positions.…”

“…Most research groups applied conventional band-pass filters to remove baseline wandering, body movements, and breathing artefacts from SCG signals [26,36,38,41,45,46,55,[58][59][60][61][62][63]67,71,75,76,[78][79][80]82,93]. A few studies utilized or proposed more advanced noise removal techniques [64,76,88,[94][95][96].…”

“…More studies are needed that compare different filtering methods in clinical and ambulatory settings. [26,36,38,41,45,46,55,[58][59][60][61][62][63]67,71,75,76,[78][79][80]82,93] Adaptive filtering Motion artefact removal [88,95] Averaging theory Motion artefact removal [101] Comb filtering Removing respiration noise from radar signal [50] Empirical mode decomposition Baseline wandering, breathing and body movement artefact removal [76,94,95] Independent component analysis Motion artefact removal [102] Median filtering [96] Morphological filtering [95] Polynomial smoothing Motion artefact removal [103] Savitzky-Golay filtering Motion artefact removal [83,103] Wavelet denoising Segmentation of HSs and SCG [64,95,96] Wiener filtering [94] 2.…”

“…In addition to human studies on healthy populations, there were several studies that focused on the application of SCG in patients with cardiovascular disease. SCG signals were used for diagnosis and monitoring of different clinical conditions such as atrial fibrillation [47,48,68,70], atrial flutter [55], heart valve disease [37,44,80], coronary artery disease and ischemia [9,10,48], myocardial infarction [126], heart failure [75,78,82,100,119], structural heart disease [80], and heart stress testing [58].…”