MAGNETOCARDIOGRAPHY IN THE SURVEILLANCE O F FETAL CARDIAC ACTIVITY

Magnetocardiography provides a new, alternative method for fetal surve illance. This method allows the registration of changes in the magneti c field produced by the fetal cardiac system. In comparison to fetal E GG, the fetal magnetocardiogram (fMCG) is not affected by intermediate tissue, in particular by the insulating effect of the vernix caseosa. Furthermore fMCG's with a good signal noise ratio can be obtained in the second trimester. A multichannel biomagnetometer allows the non-in vasive measurement of the magnetic signals produced by the fetus. Exam ples of data and evaluation techniques are given. Signal processing so ftware allows the identification of all fetal beats in a data set, per mitting the calculation of an averaged beat and the evaluation of sign al morphology and cardiac time intervals. Furthermore it is possible t o produce a beat to beat time series with high temporal resolution, ma king the evaluation of heart rate variability with measures from the t ime, frequency, and phase domain accessible. Particularly: the latter are of interest in investigating changes in temporal complexity of the fetal cardiac system. Magnetocardiography thus holds the promise of i mproved antenatal surveillance as of the second trimester.