Multichannel seismocardiography: an imaging modality for investigating heart vibrations

Abstract

Objective: Seismocardiography is the measurement of vibration waves caused by the beating heart with accelerometer(s) placed on the chest. Investigating the nature and the behavior of these vibration waves, by comparing measurements from multiple sites, would help to understand the heart’s mechanical contraction activity. Approach: Using newly designed multichannel seismocardiogram equipment, it was possible to investigate the vibration waves with 16 three-axis sensors. The equipment performed well with highly precise synchronization rate over 10 min, linear frequency response and high signal quality. The vibration waves were analyzed using the sagittal axis, a single cardiac cycle and focusing on four fiducial points. Two of the fiducial point where the negative and positive peaks associated with aorta valve opening, along with peaks associated with aorta valve closing. Main results: The respective average centers of mass of the four fiducial points in 13 subjects were at (frontal axis: 35 mm, vertical axis: 5 mm), (31, 6), (26, 24), and (4, −2), relative to the Xiphoid Process. Similar patterns among the subjects were identified for the propagation of the waves across the chest for the four fiducial points. Significance: The multichannel seismocardiogram equipment successfully revealed a general pattern present in chest surface vibration maps.

Changes in Forcecardiography Heartbeat Morphology Induced by Cardio-Respiratory Interactions

“…The analyses presented in this study could be extended to other components of FCG signals, e.g., the heart sounds captured in the HS-FCG, which are known to be affected by respiration [ 81 , 82 ], and the LF-FCG, which potentially carries information on stroke volume variations, which are also affected by respiration [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Considering that the morphology of cardio-mechanical signals is highly dependent on the specific sensor location over the chest [ 89 , 90 ], the analyses presented in this study could also be extended to multichannel measurements to be acquired by means of FCG sensor matrices.…”

Respiratory-Induced Amplitude Modulation of Forcecardiography Signals

“…Since IMUs usually also include gyroscopes, new techniques have recently been proposed, namely Gyrocardiography (GCG), which captures the rotational components of local cardiac vibrations [ 14 , 15 ]. The combined use of SCG and GCG, also from multiple sites, has further been investigated [ 16 , 17 , 18 ]. SCG and GCG have proven useful as wearable surrogates for echocardiography in estimating cardiac time intervals, which provide clinically relevant information for diagnosis and management of various cardiac pathologies [ 7 , 8 , 9 , 10 , 11 , 19 ].…”

A Novel Broadband Forcecardiography Sensor for Simultaneous Monitoring of Respiration, Infrasonic Cardiac Vibrations and Heart Sounds

“…The SCG and GCG signals thus acquired are used to compute the integral of kinetic energy, both for the linear and rotational components of body motion, which can be used to monitor the cardiac inotropic activity ( Hossein et al, 2021a , b ). Since it has been for long recognized that heart-induced vibrations measured at different sites of the chest wall show morphological differences, novel multisite measurement systems have been developed ( Lin et al, 2018 ; Di Rienzo et al, 2020 ; Munck et al, 2020 ). In particular, a multichannel SCG system based on a 4-by-4 matrix of triaxial accelerometers has been proposed by Munck et al (2020) The system allows obtaining surface vibration maps via simultaneous, multisite measurements of chest wall vibrations, thus standing as a novel kind of imaging modality for the analysis of the mechanical behavior of the beating heart ( Munck et al, 2020 ).…”

“…Since it has been for long recognized that heart-induced vibrations measured at different sites of the chest wall show morphological differences, novel multisite measurement systems have been developed ( Lin et al, 2018 ; Di Rienzo et al, 2020 ; Munck et al, 2020 ). In particular, a multichannel SCG system based on a 4-by-4 matrix of triaxial accelerometers has been proposed by Munck et al (2020) The system allows obtaining surface vibration maps via simultaneous, multisite measurements of chest wall vibrations, thus standing as a novel kind of imaging modality for the analysis of the mechanical behavior of the beating heart ( Munck et al, 2020 ). In addition to MEMS sensors, also piezoelectric sensors have been investigated for SCG recording ( Bifulco et al, 2014 ; Ha et al, 2019 ; Nayeem et al, 2020 ).…”