Magnetic Recordings of the Heart's Electrical Activity with a Cryogenic Magnetometer

Abstract

The greatest difficulty in measuring magnetic field generated by the heart's electrical activity is in eliminating noise from other sources. The common mode portion of the noise was rejected by using a magnetometer with a pair of differentially connected superconducting flux transformers. The high sensitivity associated with the two Josephson junction quantum interference device permitted highly resolved magnetiocardiograms of quality comparable to the normal electrocardiogram, without the use of shielded enclosures or signal averaging.