Detection of cardiac hypertrophy in the fetus by approximation of the current dipole using magnetocardiography

To determine the developmental changes in the myocardial current during fet al life, and to evaluate the clinical usefulness of magnetocardiography for prenatal diagnosis of cardiac hypertrophy or enlargement, we approximated the magnitude of the one-current dipole of the fetal heart using fetal magn etocardiography (fMCG). A total of 95 fetuses with gestational age of 20-40 wk were included in this study. fMCG was recorded with a nine-channel supe rconducting quantum interference device system in a magnetically shielded r oom. The magnitude of the dipole (Q) was calculated using an equation based on the fMCG amplitude obtained on the maternal abdomen and the distance be tween the maternal surface and fetal heart measured ultrasonographically. I n uncomplicated pregnancies, the Q value correlated significantly with gest ational age, reflecting an increase in the amount of myocardial current, i. e. myocardial mass. More-over, the Q values in fetuses with cardiomegaly ca used by various cardiovascular abnormalities tended to be higher than the n ormal values. Although there are some limitations of the methodology based on the half-space model, and fetal orientation may influence the magnitude of the dipole, making it smaller, fMCG recorded with a multichannel superco nducting quantum interference device system is a clinically useful tool for noninvasive, prenatal, and electrical evaluation of fetal cardiac hypertro phy.