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An important parameter to analyze the efficiency of the heart as a pump is Car- diac Ejection Fraction (EF), which is clinically highly correlated to the functional status of the heart. Diverse non invasive methods can be applied to measure EF, like Computer To- mography, Magnetic Resonance, Echocardiography, and others. Nevertheless, none of these techniques can be used to continuous monitoring of such parameter. On the other hand, elec- trical impedance tomography (EIT) may be applied to accomplish this goal. In addition, low cost and high portability are also EIT's features that justify the research for solutions in- volving such technique to monitor EF. EIT consists in reconstruct images of the conductivity distribution of the interior of a conductor domain by applying electric currents and measur- ing electrical potential on the boundary of the body. Mathematically, EIT can be classified as a non-linear inverse problem. This work proposes a method for the continuous estimation of cardiac ejection fraction, addressing it as an optimization problem. The models used in our approach assume that recent two-dimensional magnetic resonance images of the patient are available, and use them to reduce the search space. Another important feature is the parametrization of the geometry of internal inclusions inside the domain, which also reduces the cost of the method. This work proposes a Hybrid Iterated Local Search (ILS) heuristic for EIT inverse problem using Levenberg-Marquardt Method as local search. Experiments are performed on two-dimensional images with synthetically generated data for electric poten- tials. Two different protocols for current injection are tested in such experiments and prelimi- nary results are presented.

Determination of Cardiac Ejection Fraction by Electrical Impedance Tomography using a Hybrid Heuristic Approach, a Simulation Study