Static‐charge‐sensitive bed ballistocardiography in cardiovascular monitoring

Abstract

We evaluated the autonomic influence on balistocardiograms recorded by a static-charge-sensitive bed for cardiovascular monitoring in nine healthy males (20-44 years) and its clinical use in 11 patients who underwent coronary bypass surgery (51-59 years). The ballistocardiogram displayed a distorted low amplitude from the empty beating heart during bypass surgery, impaired by a reduced effective transmural filling pressure of the heart, and returned to its pre-bypass level when the preload to the heart and its pumping was restored. Submaximal dynamic exercise and isoprenaline caused the heart rate to rise to 90-114 beats min-1, and increased the ballistocardiographic amplitude threefold, while at the same time shortening the interval between the R-wave of the electrocardiogram and the peak of the ballistocardiographic waveform (P < 0.01). In contrast, atropine accelerated the heart rate to 96 beats min-1, but did not significantly change the amplitude or temporal pattern of the ballistocardiogram. Thus, the ballistocardiogram reflects sympathetic and parasympathetic influence on the contractility of the myocardium and the effect of cardiac filling (e.g. during bypass surgery).

Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Theory and Practice

“…This method has been recently implemented using inexpensive and convenient instrumentation such as chairs [102], beds [103], weighing scales [104], and on-body accelerometers [105]. Although BCG provides a proximal waveform [106, 107], it can be applied at a distal location (e.g., from the feet with a weighing scale [104] or the wrist with an accelerometer [108]). Flexible strain or pressure sensors placed over a superficial artery can measure waveforms indicative of BP via the tonometric principle [109–112].…”

A Novel System Identification Technique for Improved Wearable Hemodynamics Assessment

“…These error metrics were the R-J interval, R-I interval, and I-J amplitude. These values are classical BCG measures of different cardiac metrics, and a good reconstruction of the COM BCG should accurately reproduce these values [7, 13, 16]. The average of these three values across all recordings and folds was determined and used as a composite error score to select each parameter in the model.…”

Toward Continuous, Noninvasive Assessment of Ventricular Function and Hemodynamics: Wearable Ballistocardiography

“…Ballistocardiography (BCG), the measurement of the mechanical forces of the body in reaction to cardiac ejection of blood [12–14], has shown promise in recent studies for offering a possible solution to this technological need. Robust BCG measurements have been demonstrated using beds [15, 16], chairs [17], and modified home weighing scales [14], and were shown to correlate strongly to changes in cardiac output [11], contractility [18, 19], and beat-by-beat left ventricular function [14]—all three of these representing central aspects of mechanical function.…”

“…However, since the morphology and timing of these signals is significantly different from BCG signals measured using the weighing scale [26], or other historical techniques such as the Starr Table [12], the analysis and interpretation techniques developed for BCG signals should not directly be applied to these wearable acceleration measurements. For example, while the time interval between the electrocardiogram (ECG) R-wave peak and the BCG J-wave peak – the R-J interval – was typically 250 ms for a healthy adult [18] measured with the static-charge-sensitive bed apparatus, and ranged from 203–290 ms for 92 healthy subjects participating in a study with the weighing scale system [27], for the accelerometer-based wearable system the R-J interval was found to be between 150–180 ms [24]. Similar results were found by Wiard, et al, with an accelerometer-based BCG system where the R-J interval was 133 ms [28].…”