Transcatheter measurement of myocardium electrical impedance: 2 versus 3 electrode method

We are interested in the use of electrical impedance spectroscopy for on-line in-situ monitorization of the state of the myocardium tissue using a transcatheter method. In this study we evaluate a new 3 electrode measurement method (3EM) in comparison with the standard two electrode method (2EM). We analyze the effect of the tip distance to the myocardium wall and the catheter angle for both methods. We used the finite element model in order to compare both measurement methods. Experimental in-vitro measurements were performed to validate the mathematical model. Results show that the measured impedance depends of the contrast (conductivity of blood divided by conductivity of tissue) and the distance. This dependence is stronger for the 2EM than for the 3EM. The impedance spectrum with the 3EM is more appropriate than the 2EM for tissue characterization.