Recommended Standards for Fetal Magnetocardiography

Fetal magnetocardiography (FMCG) is increasingly being used in research and diagnostics of fetal heart function. Currently, FMCG is the only noninvasive procedure available, comparable to postnatal ECG, which can be used to assess cardiac electrophysiology during the second and third trimester of pregnancy. For a reliable evaluation and full clinical acceptance of this new technique, large numbers of patient investigations are required which can only be obtained in multicenter studies. An international standard protocol is needed to allow pooling of sufficient data and to permit the comparison of studies performed in different centers. This article provides recommended standards for FMCG in the fields of data acquisition and data analysis.

Clinical implications of fetal magnetocardiography

OBJECTIVES

To test the usefulness and reliability of fetal magnetocardiography as a diagnostic or screening tool, both for fetuses with arrhythmias as well as for fetuses with a congenital heart defect.

METHODS

We describe 21 women with either a fetal arrhythmia or a congenital heart defect discovered during prenatal evaluation by sonography. Four fetuses showed a complete atrioventricular block, two an atrial flutter, nine ventricular extrasystole, and one a complete irregular heart rate. Five fetuses were suspected to have a congenital heart defect. In all cases magnetocardiograms were recorded.

RESULTS

Nine fetuses with extrasystole showed a range of premature atrial contractions, premature junctional beats or premature ventricular contractions. Two fetuses with atrial flutter showed typical flutter waves and four fetuses with complete atrioventricular block showed an uncoupling of P-wave and QRS complex. One fetus showed a pattern suggestive of a bundle branch block. In three of four fetuses with confirmed congenital heart defects the magnetocardiogram showed abnormalities.

CONCLUSION

Fetal magnetocardiography allows an insight into the electrophysiological aspects of the fetal heart, is accurate in the classification of fetal arrhythmias, and shows potential as a tool in defining a population at risk for congenital heart defects.

Monitoring the fetal heart non-invasively: a review of methods

Doppler ultrasound, ultrasound M-mode analysis, fetal electrocardiography, and fetal magnetocardiography are methods by which the fetal heart can be monitored non-invasively. In this paper, they are evaluated and compared. Customarily, it is solely the fetal heart rate, which is monitored using the Doppler ultrasound technique since it is both simple to use and cheap. However, this method inherently produces an averaged heart rate and therefore cannot give the beat-to-beat variability. Fetal electrocardiography has similar advantages, but in addition offers the potential for monitoring beat-to-beat variability and performing electrocardiogram morphological analysis. Its disadvantage is that its reliability is only 60%, although it is the only technique that offers truly long-term ambulatory monitoring. Ultrasound M-mode analysis allows a estimation of atrial and ventricular coordination, as well as an estimation of PR intervals. Bradycardias, supraventricular tachycardias, extra systoles are readily diagnosed using this method although timing will be inaccurate. Fetal magnetocardiograms can be detected reliably and used for accurate beat-to-beat measurements and morphological analysis. Consequently, they can be used for the classification of arrhythmias and the diagnosis of a long QT syndrome and some congenital heart diseases.