A device and a method for working with electromagnetic fields, specifically those fields that occur in image-guided nuclear spin tomography examinations (MRT or MRI). More precisely, the invention concerns an at least partially implanted medical device (IMD) that permits the delivery of electrical stimulation impulses by an electrode only in timeframes, in which no electromagnetic interferences are recognized and/or the control unit performs a reconstruction of electrical measurements for the timeframes in which electromagnetic interferences are recognized.