PRENATAL REGISTRATION OF FETAL HEART ACTI VITY BY MAGNETOCARDIOGRAPHY

Fetal magnetocardiography (fMCG) registers the magnetic field generate d by the fetal heart. In contrast to the fetal electrocardiogram, fECG permits non-invasive registration of fetal heart activity and documen tation of all parts of the PQRST-wave-forms from the second trimenon o nwards. This facilitates the determination of cardiac time intervals a nd establishment of reference values for different stages of pregnancy . We examined 53 women in 104 recordings from the 10th week of gestati on onwards (1 to 10 recordings per individual). The fMCG (37 magnetic channels, sampling rate 1024 Hz, bandwidth 1-200 Hz) was recorded non- invasively over the mother's abdomen in a magnetically shielded room. Registration of fetal heart beats was generally successful from the 20 /21th week of gestation onwards. In a few cases, fetal heart beats cou ld be registered as early as in the 16th week. Cardiac time intervals and amplitudes of fMCG increased concordantly with fetal growth. Mean P wave duration increased from 31 to 49 ms (p < 0.05), PQ interval fro m 95 to 107 ms (n. s.) and QRS duration from 36 to 52 ms (p < 0.01). T he mean amplitudes of the P and R waves also increased. FMCG, furtherm ore permits a prenatal diagnosis of fetal cardiac arrhythmias. We reco rded fetal arrhythmias in 20 cases (26-38th week), including episodes of ventricular and supraventricular arrhythmias or atrioventricular bl ockings. Due to its high resolution, fMCG offers new information on th e development of fetal cardiac activity which cannot be achieved by co nventional methods like cardiotocography or dopplerultrasound. Therefo re, fMCG could become a new diagnostic instrument for monitoring fetal wellbeing during pregnancy.