Multi-dimensional Kineticardiography a New Approach for Wearable Cardiac Monitoring Through Body Acceleration Recordings

We present a novel technique for the wearable monitoring of the mechanical characteristics of the cardiac contraction. Multi-dimensional Kineticardiography (MKCG) represents an important evolution of the old Ballistocardiography (BCG) technique. It consists in measuring the full body kinetic energy in its 6 degrees-of-freedom via a 3-axis accelerometer and 3-axis gyroscope placed at the surface of the body close to center-of-mass of the subject while BCG mainly consisted in measures on a single axis (feet-to-head). We present signal processing techniques and methods that provides a complete new window on the cardiac function. The following scalar parameters independent from the frame of reference are computed: magnitude of force and torque of contraction, linear and rotational component of kinetic energy, work and power as well as ratios of the rotational over linear component. We show here for the first time recordings of total and rotational kinetic energy in normal and a small population of patients suffering from mild to severe heart insufficiency or valvulopathy. In all cases the rotational component of the kinetic energy transferred from the heart to the body represented more than 60 % of the total. We further show that the ratio of rotational over total energy (Er/Et) is significantly decreased in the heart failure population compared to young healthy normal. This shows the advantages of our Multi-dimensional kineticardiography over the past single axis ballistocardiography.