1. A device for the reconstruction of a surface electrocardiogram (ECG), comprising: a plurality of inputs, corresponding to a plurality of signals from endocardial or epicardial electrograms each acquired on a respective channel of a plurality of channels; at least one output delivering a reconstructed surface ECG signal, relative to an ECG channel; and a plurality of non-linear digital filters corresponding to each of the plurality of inputs, wherein the non-linear digital filters are Volterra type filters with a transfer function such that the combination of the non-linear digital filter outputs reconstructs the surface ECG signal based on the plurality of inputs, the transfer function including a linear term and at least one quadratic and/or cubic term(s).