Beat-by-Beat Quantification of Cardiac Cycle Events Detected From Three-Dimensional Precordial Acceleration Signals

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Signal Processing

Background:

• Seismocardiography (SCG) noninvasively records cardiovascular vibrations using accelerometers.
• Understanding the precise physiological basis of SCG signals, especially in 3-D, remains a challenge.
• Existing research primarily focuses on the back-to-front axis, with limited quantification of 3-D SCG events.

Purpose of the Study:

• To develop and validate a method for quantifying 3-D seismocardiograms in relation to cardiac cycle events.
• To investigate the spatial distribution of cardiac cycle events in 3-D SCG signals.
• To explore the potential of 3-D SCG event distribution for differentiating healthy individuals from patients with cardiac conditions.

Main Methods:

• Cardiac cycle events were identified from 3-D seismocardiograms.
• A novel method assigned numerical values to events based on their spatial location.
• Analysis included data from 9 healthy subjects (396 events) and 120 events from patients with atrial flutter.

Main Results:

• Despite low intersubject waveform correlation (0.05-0.27 across axes), the method identified consistent spatial patterns in healthy subjects.
• Cardiac cycle event coordinates in healthy individuals clustered around specific locations.
• These spatial distributions differed significantly in patients with atrial flutter compared to healthy controls.

Conclusions:

• Spatial distribution of cardiac cycle events in 3-D seismocardiograms exhibits latent similarities within healthy populations.
• The identified spatial patterns are distinct between healthy individuals and those with atrial flutter.
• 3-D seismocardiography event localization shows promise as a noninvasive tool for discriminating cardiac health status.