Non-invasive assessment of the heart function in unshielded clinical environment by SQUID gradiometry

Bioelectrical activity of the heart produces minute magnetic fields that may be measured above the torso with superconducting quantum interference device (SQUID) sensors. A new application has been developed which permits noninvasive assessment of the heart function in unshielded magnetically harsh clinical environment. The system incorporates a multichannel SQUID system, a supine nonmagnetic ergometer, a peripheral data interface and software tools for processing magnetocardiographic data. To demonstrate the performance of the method, biomagnetic measurements have been performed both at rest and during physical exercise. Signal processing, signal-to-noise ratio and artifact rejection procedures have been discussed.