Assessment of left ventricular twist by 3D ballistocardiography and seismocardiography compared with 2D STI echocardiography in a context of enhanced inotropism in healthy subjects

Abstract

Ballistocardiography (BCG) and Seismocardiography (SCG) assess the vibrations produced by cardiac contraction and blood flow, respectively, by means of micro-accelerometers and micro-gyroscopes. From the BCG and SCG signals, maximal velocities (V _Max), integral of kinetic energy ( iK), and maximal power (P _Max) can be computed as scalar parameters, both in linear and rotational dimensions. Standard echocardiography and 2-dimensional speckle tracking imaging echocardiography were performed on 34 healthy volunteers who were infused with increasing doses of dobutamine (5–10–20 μg/kg/min). Linear V _Max of BCG predicts the rates of left ventricular (LV) twisting and untwisting (both p <  0.0001). The linear P _Max of both SCG and BCG and the linear iK of BCG are the best predictors of the LV ejection fraction (LVEF) ( p <  0.0001). This result is further confirmed by mathematical models combining the metrics from SCG and BCG signals with heart rate, in which both linear P _Max and iK strongly correlate with LVEF (R = 0.7, p <  0.0001). In this setting of enhanced inotropism, the linear V _Max of BCG, rather than the V _Max of SCG, is the metric which best explains the LV twist mechanics, in particular the rates of twisting and untwisting. P _Max and iK metrics are strongly associated with the LVEF and account for 50% of the variance of the LVEF.