Medical devices and methods for making and using medical devices are disclosed. A method for removing an artifact of a biological reference signal present in a biological source signal may comprise sensing a biological reference signal with one or more electrodes and sensing a biological source signal, wherein the biological source signal comprises an artifact of the biological reference signal. The method may further comprise determining, based on the biological reference signal, the artifact of the biological reference signal and subtracting the artifact of the biological reference signal from the sensed biological source signal.