Interpreting biomagnetic fields of planar wave fronts in cardiac muscle

The recent results of Holzer and co-workers reveal the existence of net currents that flow along the front of a planar wave propagating through cardiac tissue. This is an important contribution toward the better understanding of the physics of biomagnetic fields. However, although the authors claim their results reveal particular bidomain properties, we show in this short letter that the results allow multiple interpretations. For instance, cardiac anisotropy by itself may also explain the existence of a net current along the wave front. Based on our calculations, we suggest additional experiments that would allow distinguishing between these two explanations and thus provide further evidence on the basic physics behind cardiac biomagnetism.