Objectives Magnetocardiogram (MCG) with superconducting quantum interference device can measure cardiac electrical activity and has non-contact characteristics, and is not interfered with lung filed. We newly developed and tested the validity of micro MCG for small animals using superconducting quantum interference device (SQUID) on a single silicon chip.
Methods Ten male Hartley guinea pigs (250g) were anaesthetised with pentobarbital. Platinum needle electrodes were attached to animals. Excessive quinidine (60mg/kg) was administered intraperitoneally. MCG and ECG were recorded simultaneously at baseline, 3, 5, 7, 10, 15 min after injection. QT interval was automatically analysed by Power Lab and QTc was calculated by Bazett formula.
Results In ginea pigs, QTc was prolonged from 284 ± 10 to 299 ± 11msec in ECG (QTc-ECG). QTc was prolonged from 280 ± 16msec to 295 ± 10msec in MCG (QTc-MCG). QTc-MCG correlated well with QTc-ECG at baseline (r2 = 0.944, p < 0.0001) and at 15min after injection (r2 = 0.780, p = 0.0007).
Conclusions Newly developed micro MCG for small animals with a single chip SQUID array enabled us to measure drug-induced QT prolongation by milli-seconds. This system may facilitate the high throughput screening test and also basic scientific research of electromagnetic properties of the small animal heart.