Magnetocardiographic and Electrocardiographic Exercise Mapping in Healthy Subjects

myocardial ischemia is based on ST-segment changes in exer-cise testing. Magnetocardiography MCG is a complementary method to the ECG for a noninvasive study of the electric activity of the heart. In the MCG, ST-segment changes due to stress have also been found in healthy subjects. To further study the normal response to exercise, we performed MCG mappings in 12 healthy volunteers during supine bicycle ergo-metry. We also recorded body surface potential mappings BSPM with 123 channels using the same protocol. In this paper we compare, for the first time, multichannel MCG re-corded in bicycle exercise testing with BSPM over the whole thorax in middle-aged healthy subjects. We quantified changes induced by the exercise in the MCG and BSPM with param-eters based on signal amplitude, and correlation between signal distributions at rest and after exercise. At the ST-segment and T-wave apex, the exercise induced a magnetic field component outward the precordium and the minimum value of the MCG signal over the mapped area was found to be amplified. The response to exercise was smaller in the BSPM than in the MCG. A negative component in the MCG signal at the repo-larization period of the cardiac cycle should be considered as a normal response to exercise. Therefore, maximum ST-segment depression over the mapped area in the MCG may not be an eligible parameter when evaluating the presence of ischemia. Keywords—Magnetocardiography, Body surface potential mapping, Exercise test, Myocardial ischemia. © 2001 Bio-medical Engineering Society. DOI: 10.1114/1.137638