Optical Vibrocardiography: A Novel Tool for the Optical Monitoring of Cardiac Activity

Abstract

We present an optical non-contact method for heart beat monitoring, based on the measurement of chest wall movements induced by the pumping action of the heart, which is eligible as a surrogate of electrocardiogram (ECG) in assessing both cardiac rate and heart rate variability (HRV). The method is based on the optical recording of the movements of the chest wall by means of laser Doppler interferometry. To this aim, the ECG signal and the velocity of vibration of the chest wall, named optical vibrocardiography (VCG), were simultaneously recorded on 10 subjects. The time series built from the sequences of consecutive R waves (on ECG) and vibrocardiographic (VV) intervals were compared in terms of heart rate (HR). To evaluate the ability of VCG signals as quantitative marker of the autonomic activity, HRV descriptors were also calculated on both ECG and VCG time series. HR and HRV indices obtained from the proposed method agreed with the rate derived from ECG recordings (mean percent difference <3.1%). Our comparison concludes that optical VCG provides a reliable assessment of HR and HRV analysis, with no statistical differences in term of gender are present. Optical VCG appears promising as non-contact method to monitor the cardiac activity under specific conditions, e.g., in magnetic resonance environment, or to reduce exposure risks to workers subjected to hazardous conditions. The technique may be used also to monitor subjects, e.g., severely burned, for which contact with the skin needs to be minimized.

Assessing mechanical properties of tissue phantoms with non-contact optical coherence elastography and Michelson interferometric vibrometry

“…Laser vibrometry was first applied in different engineering fields, such as modal analysis, vibration and noise testing, characterizing loudspeakers, and assessing piezoceramic transducers [25]. Recently, laser vibrometry has gained traction in biomedical and bioengineering applications, such as auditory research [26,27], dentistry [28,29], cardiology [30][31][32], as well as elastography and rheology [33][34][35][36][37][38].…”

Non Contact Heart Monitoring

“…First studies using optical vibrometry (laser Doppler vibrometry) has been reported for the identification of the arterial pressure waves (Tomasini et al in 1998). While a novel method, called vibrocardiography (VCG), has been later proposed to measure the velocity of displacement of the skin in correspondence of the chest wall (Scalise et al, 2005a;2005b;Morbiducci et al, 2006;Scalise and Morbiducci, 2008). VCG has been demonstrated to be valid for the assessment of the cardiac frequency and variability and in Cardiac Resinchronization Theraphy as support in pacemaker programming after installation (Bocconcelli et al, 2006).…”

Attacks on Heartbeat-Based Security Using Remote Photoplethysmography

“…While most studies that suggest heartbeat-based security (HBBS) for mHealth assume that physical contact is required to generate the same identifier from IPIs, an increasing number of studies suggest that heartbeats may be measured remotely using, for example, Doppler radar [8], capacitive coupling [9], optical vibrocardiography [10], ballistocardiography [11], (thermal) imaging [12], [13] and even through detecting minute difference in a person's voice [14]. Such techniques are primarily intended to have a positive impact on healthcare, for example, by monitoring an infant incubator without touching the frail infant [15].…”