Influence of sympathetic activation on myocardial contractility measured with ballistocardiography and seismocardiography during sustained end-expiratory apnea

Abstract

Ballistocardiography (BCG) and seismocardiography (SCG) assess vibrations produced by cardiac contraction and blood flow, respectively, through micro-accelerometers and micro-gyroscopes. BCG and SCG kinetic energies (KE), and their temporal integrals (iK) during a single heartbeat are computed in linear and rotational dimensions. Multiunit muscle sympathetic nerve traffic (BF, burst frequency; tMSNA, total muscular sympathetic nerve activity) was measured by microneurography during normal breathing and apnea (n=28, healthy men). iK of BCG and SCG were simultaneously recorded along with oxygen saturation (SatO2) and systolic blood pressure (SBP).The mean duration of apneas was 25.4±9.4s. SBP, BF, tMSNA increased during the apnea compared to baseline (p=0.01, p=0.002, p=0.001, respectively), while SatO2 decreased (p=0.02). At the end of the apnea compared to normal breathing, changes of iK computed from BCG were related to changes of tMSNA and BF only in the linear dimension (r=0.85, p<0.0001; r=0.72, p=0.002, respectively), while changes of linear iK of SCG were related only to changes of tMSNA (r=0.62, p=0.01).Maximal end expiratory apnea increases cardiac kinetic energy computed from BCG and SCG, along with sympathetic activity. The novelty of the present investigation is that linear iK of BCG is directly and more strongly related to the rise in sympathetic activity than the SCG, mainly at the end of a sustained apnea, likely because the BCG is more affected by the sympathetic and hemodynamic effects of breathing cessation. BCG and SCG may prove useful to assess sympathetic nerve changes in patients with sleep disturbances.

Quantification of Cardiac Kinetic Energy and Its Changes During Transmural Myocardial Infarction Assessed by Multi-Dimensional Seismocardiography

“…We presented a device capable of computing the integral of kinetic energy of a contractile cycle recorded with microaccelerometers and gyroscopes, with the aim to provide information on the mechanical activity of the heart. We previously demonstrated the capability of this device to follow changes of cardiac contractility in different conditions as already mentioned (2,12,31,32,42). With the present investigation, we add that this device can detect an acutely failing heart of ischemic origin by providing a parameter of kinetic energy.…”

“…We reported for the first time the direct evidence that noninvasive, multi-dimensional SCG can quantify the cardiac kinetic energy and continuously track its changes during AMI and reperfusion in a closed chest swine model of AMI. We have previously highlighted the potential of micro-accelerations and gyroscopes in providing reliable information on the contractility status of the heart (2, 30): as found in previous study, metrics of iK are able to follow changes in cardiac contractility with high accuracy and were related to SV and CO (2); the increased cardiac kinetic energy measured with micro-accelerometers and gyroscopes was directly related to the rise of sympathetic nerve traffic during an end-voluntary maximal apnea (31); signals acquired with multi-dimensional SCG and BCG could monitor cardiac deconditioning in astronauts during simulated microgravity (32). With the present research, we demonstrate, for the first time, that the cardiac kinetic energy recorded with multi-dimensional non-invasive SCG, along with hemodynamic and echocardiographic findings, drops during AMI compared to normal cardiac inotropic state and does not improve during coronary reperfusion (33), likely reflecting a reduced left ventricular function of ischemic origin and further confirmed by the rise of plasma troponin levels and the drop of LVEF associated with regional LV wall abnormalities, which persisted despite revascularization.…”

“…Despite the fact that this technique has not been standardized yet with large-scale-based studies so that no normal values of kinetic energy can be provided, this limitation was encompassed with the repeated-measures study design, where each animal was its own control. The same study design was adopted in our previous works (2,12,31,32,42).…”

Kinocardiography Derived from Ballistocardiography and Seismocardiography Shows High Repeatability in Healthy Subjects

“…These metrics have been shown to be computable based on BCG and SCG signals acquired using different sensors at either 1 kHz or 50 Hz indifferently [ 13 ]. In other studies, differences in KCG metrics have also been associated with an increase during voluntary apnea [ 14 ], an increase during simulated obstructive apnea [ 15 ], an increase during sympathetic activation [ 16 ] and a decrease during a deconditioning that occurred during long-duration head-down tilt bed rest [ 17 ]. Establishing the reliability of these measures is crucial to the continued investigation of such interindividual and group-based differences.…”

A Comprehensive Review on Seismocardiogram: Current Advancements on Acquisition, Annotation, and Applications

“…The proposed method used adaptive recursive least squares filters for removing the motion artifacts. In [62], the kinetic energies and their temporal integrals in linear as well as rotational dimensions were computed according to both SCG and BCG signals. A study was conducted to test that the kinetic energy from SCG and BCG are related to sympathetic activation during maximal voluntary end-expiratory apnea.…”