Complex narrow band-pass filters for QRS detection in contactless magnetocardiograms of small animals

Recently, magnetocardiography (MCG) of small animals was proposed for the investigation of drug safety and for phenotype characterization of genetically modified mice. MCG is a contactless measurement method to provide information very similar to the ECG. In order to cover the wide variation of signal shape and frequency content of the heart signals of small animals, we used a complex narrow-band filter characterized by center frequency and bandwidth as a preprocessor for QRS detection. We applied the method to MCG signals of rabbits, hamsters, guinea pigs and mice. While in human MCGs the preferential center frequency of the bandpass filter is 20 Hz at a bandwidth of 2 Hz, the respective values for rabbits are 40(4) Hz, for guinea pigs 40(4) Hz, for hamsters 100(10) Hz, and for mice 150(30) Hz. The method works stable even in cases where the signal to noise ratio is only 2:1