L Lopez

Clinical value of magnetocardiography

Magnetocardiography, that is to say the recording of the magnetic field generated by the electrical activity of the heart, was born in 1963 when Baule and McFee, using an induction coil, measured for the first time magnetic signals produced by a human heart [2]. Since then, the evolution from a pioneering experimental observation to the present state of art has passed through fundamental technological progress. First, in 1970, the introduction of superconducting instrumentation in the MIT shielded room demonstrated that magnetocardiograms of quality comparable with that of standard electrocardiograms could be recorded [6, 8, 36]. The next important step was the adoption of gradiometric detection coils which allowed MCG recording in unshielded laboratories [1, 3, 33,44, 47] and opened the way to pioneering clinical measurements [4, 16, 18]. During the same years MCG were also recorded without a superconducting instrumentation [9]. Since the beginning the question arose whether or not magnetic measurements could increase the diagnostic capability of cardiologists in respect to more conventional methods. Several different approaches were used to quantify the information [5, 8, 33, 39] and, although some authors still favour analysis of MCG signal in the time domain both at standard [7, 28, 49] as well as at high resolution [38] isofield contour maps are nowadays preferred to give images of the magnetic field distribution during depolarization and repolarization [10, 11, 13, 21, 22, 27, 29].