Intra-Cardiac Bioimpedance Field Variability with Breathing

Abstract

This study was made to evaluate the sensitivity of intracardiac bioimpedance measurement to breathing. Electric field generated by two electrodes carried by an intracardiac catheter is simulated in the chest model of Visible Human Man (VHM). The breathing introduced to the model was done by changing the impedance of the lung between inflated and deflated cases. The actual motion of the chest anatomy due to breathing was not yet modelled at this stage. The electric field was calculated with Finite Difference Method (FDM) on a regular mesh containing about 2.7 million nodes. The frequency chosen for this simulation was 100 kHz as it is in the range of the most used bioimpedance measurement frequencies. The bioimpedance simulation results show that the field generated with the catheter electrodes is not very homogeneous. The standard deviation of the angle of field gradient vector is 19.18 degrees with deflated lung and 18.95 degrees with inflated lung. On the other hand, the field does not change very much, having only 0.69 degrees between the average values of deflated and inflated gradient vectors inside the LV.