Magnetocardiography in the assessment of fetal arrhythmias

Arrhythmias in the fetus are common, comprising 15–20% of referrals for fetal cardiac evaluation. The diagnosis of such arrhythmias rests on assessment of the mechanical sequence of contraction by M-mode, pulsed and tissue Doppler echocardiography. However, precise electrophysiological data – including beat-to-beat variability; QRS, QT and P-wave duration; and repolarization characteristics – can only be elucidated by fetal electrocardiography or magnetocardiography. Although fetal magnetocardiography is expensive, not widely available and is used primarily for research, the electrophysiological data gleaned from this technique have made the diagnosis and treatment of fetal arrhythmias more accurate, provided insight into the mechanism of these arrhythmias and furthered the understanding of human developmental electrophysiology.