A high-Tc dc-SQUID-based single-channel MCG and its performance
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A single-channel high-Tc dc-SQUID magnetometer and gradiometer have been developed to record the magnetic field component perpendicular to the human chest generated by heart-beat. Magnetocardiogram (MCG) measurements have been carried out inside a magnetically shielded room. By sequentially adjusting a non-magnetic patient table with 5 cm pitch in X and Y directions, the field signals on a rectangle grid 5 × 5 over the chest area were registered in real time trace point by point with a typical dwell time over 30 cardiocycles each. Utilizing standard electrocardiogram (ECG) recordings as timing reference measured simultaneously with the MCG signals, the MCG data were then averaged and combined to form magnetic field patterns every 10 ms or so. Both the current dipole, which is parallel to MCG measuring plane and produces the vertical magnetic field, and its depth were determined as a function of time in a standard way. We have compared the MCG of healthy hearts with that of a heart with right bundle branch block. Significant differences between their MCGs have been observed.
Keywordshigh-Tc dc-SQUID magnetocardiogram QRS complex
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