The effect of breathing on Stroke Volume estimation in patients with implanted cardiac device using parametric electrical impedance tomography

Correlating changes in the thoracic conductivity distribution with the volume changes of the heart can help providing a non-invasive Stroke Volume (SV) quantification method. Electrical Impedance Tomography is a non-invasive non-ionizing imaging technique in which tissues can be diferentiated based on their electrical properties. The method uses measured surface potentials in order to reconstruct information of the spatial conductivity distribution within the thorax. In the current study, parametric ElT (PElT) scheme was applied in a high-resolution 4D model of the human thorax to determine the left ventricular volume (LVV) at different cardiac cycle phases. The effect of breathing is examined by allowing both heart and respiratory motions. The results emphasize the fact that the estimation of the LVV using pElT is affected by breathing. About J 0% change in the lungs´ volume causes 8% change in the estimated Sv. The contribution of both motions to the change of potential distributions can be separated. The separated potential distributions are used to estimate the LVV while neutralizing the effect of breathing. The preliminary results show a decrease in the SV estimation error; 3% compared to 12% without using the correction algorithm. The results suggest that the LVV can be estimated using pElT method while neutralizing the effect of respiratory motion and that the method has the potential to be used for monitoring purposes.