Validation of Kinocardiography, a New Technology Measuring Cardiac Mechanical Activity Via Accelerometers and Gyroscopes

Kinocardiographic measures mechanical and electrical function of the heart. The proposed solution is based on measurements of body vibrations. By measuring these movements on the surface of the body, it is possible to deduce, taking into account the individual's weight and size, the quality of the heartbeat that caused this vibration. The technique developed consists of a device measuring these vibrations at two places in the body: on the torso (Seismocardiography) and on the lower back (Ballistocardiography). The first measurement is a reflection of the local strength of the heartbeat as well as the transmission of blood to the body's main artery, the aorta. The second measurement, in the lower back, is the result of the contraction and movement of blood within the arterial system. Based on these two measurements, the energy produced by the heart and transmitted to the torso or the whole body is calculated. The energy over an entire cardiac cycle and the distribution of that energy within a heartbeat are used to characterize the mechanical function of the heart. Clinical studies carried out previously have demonstrated the repeatability of kinocardiographic measurements (KCG) and their robustness with respect to the use of different sensors. KCG measurements also showed a high sensitivity (\> 94%) to different hemodynamic states induced by the injection of active inotropic agents, i.e. dobutamine also used as a treatment for heart failure in an advanced stage. In a randomized, double-blind, cross-over study controlled by Placebo, these measurements showed a strong correlation (r = 0.8, p \<0.0001) with cardiac output measured by echocardiography. The technique has also demonstrated its ability to track changes in cardiac mechanical function during expiratory voluntary apnea. KCG measurements were also evaluated during a micro-gravity simulation in Bedrest on 23 healthy volunteers. The measurements tracked cardiac deconditioning in the control group compared to the exercise group similarly to cardiac MRI measurements. Subsequently, KCG metrics showed an ability to distinguish reduced ejection fraction (HFrEF) heart failure patients from non-insufficient patients. These latest results also showed that the chest sensor alone was sufficient to separate HFrEF patients from normative patients, laying the foundation for possible use of the smartphone alone. The prototype of a mobile application, named OKCARDIO, makes it possible to take measurements perfectly similar to the Kino thoracic sensor, but to date have never been used it in a clinical study. Such a tool would allow anyone with a smartphone-type mobile phone to measure their cardiac mechanical function themselves and make it available to the attending physician.