Assessment of cardiac apex kinematics using a real-time 3D magnetic tracking system

The assessment of left ventricular apex (LVA) kinematics throughout the cardiac cycle could be useful for evaluating cardiac performance and efficiency. We proposed and evaluated in a sheep the use of a real-time 3D magnetic tracking system for the analysis of LVA kinematics. LVA kinematics was assessed using a real-time 3D magnetic tracking system, whose sensor was epicardially glued on the exposed LVA. Two indexes were calculated from the 3-Dimensional apex path traced by the magnetic sensor: the 3D Apex Path Length (3DAPL, length of 3D apex path) and the 3D Apex Path Volume (3DAPV, volume containing 3D apex path). Hemodynamic index of cardiac contractility (LVdP/dtMAX) was derived from Left Ventricular Pressure (LVP) measurement and evaluated against LVA kinematics parameters, at baseline and after acute ischemia, experimentally induced by coronary ligation. Results showed an opposite trend between LV hemodynamics and LVA kinematics: in the ischemic heart an increase of both 3DAPL (+24.5%) and 3DAPV (+151.7%) occurred compared with baseline, while LVdP/dt_MAX decreased (-36.9%).