The use of electrocardiographic imaging for the localization of the undesired premature ventricular contraction needs a torso volume conductor definition. This study aims to investigate the specific effect of lung and blood cavity inhomogeneities on the performance of inverse localization. Two source models were assumed for the inverse solution applied to clinical data; potential on the closed epicardial-endocardial surface and a single dipole. The results showed that the potential-based solution performed better if the presence of at least blood cavities was assumed, while the dipole-based solution was not significantly influenced by the presence of inhomogeneities. The importance of the inhomogeneities in the torso model for the inverse solution also depends on the used model of the equivalent heart generator.