A 3D model of the thorax for seismocardiography

Seismocardiography (SCG) is measurement of sternal acceleration caused by heart beats. Although fiducial cardiac events have been associated with seismocardiogram extrema, the forces that cause the vibrations are unknown. The goal of this study was to create a 3D model of the thorax capable of modelling its vibrations under heart-like forces. We used the standard equations for damped elastic wave propagation. The mechanical properties of sternal and costal bone, as well as costal cartilage and lung tissue were identified. Displacement was fixed at 0 where the ribs reached the spine, a force was input where the heart was in direct contact with the thorax. The simulation was run on a life-like volume mesh. A zone of observation was identified on the xiphoid process, where normal displacement was averaged. This average was considered to simulate seismocardiograms and exhibited clear fiducial point analogs that were detectable automatically. In the next steps, we will couple the thoracic deformation model to a 3D beating heart model, incorporating contact boundary conditions that take into account the pericardium. Ultimately, we will create a thoracic model capable of returning seismocardiogram signals to enable solving inverse problems, and patient-specific modelling.