Theresa Menéndez

Prenatal diagnosis of QT prolongation by magnetocardiography.

Magnetocardiogrciphy constitutes a new tool for monitoring fetal cardiac activity. The fetal magnetocardiogram (FMCG) recorded noninvasively over the maternal abdomen is detectable with high temporal resolution and permits analysis of all parts of the PQRST waveform. In this way measurements of cardiac time intervals, including the QT interval, become possible. The following article constitutes the first report of antenatal detection of QT prolongation in two fetuses by FMCG.

Usefulness of magnetocardiography for the investigation of fetal arrhythmias

The electrical excitation of the heart causes weak magnetic fields that can be recorded without skin contact over the body surface. Cardiac magnetic activity measures in the range of 0.2 to 5 picotesla (pT) in fetuses and 50 pT in adults, thus approximately 1 million times weaker than the static magnetic field of the earth. Therefore, it was not until the introduction of highly sensitive Superconducting Quantum Interference Device detectors and multichannel equipment that sensitive and low-noise registrations of cardiac magnetic fields became feasible in clinical practice. In 1974, the first fetal “magnetocardiogram” was published by Kariniemi and coworkers 1 ; later studies demonstrated the ability of magnetocardiography (MCG) to detect noninvasively fetal cardiac activity with high resolution and success rates from the second trimester onward. 2‐ 4 MCG provides information equivalent to the surface electrocardiogram (ECG), which is obviously unsuccessful in fetuses. Especially in late pregnancy, the signal of the fetal ECG is severely attenuated due to the insulating properties of the vernix caseosa and volume conduction effects. 5 Although Doppler echocardiography constitutes the gold standard for the analysis of fetal arrhythmias, MCG offers insights into electrophysiologic features of prenatal arrhythmias. An increasing number of recent publications emphasize interest in this field. 6‐ 9 In the present study, we investigated the feasibility of MCG in a clinical work routine to

Investigation of Fetal Cardiac Arrhythmias by Magnetocardiography

While the recording ofthe fetal ECG is difficult or impossible especially during late pregnancy [1, 41, fetal magnetocardiography (fMCG) permits the registration of fetal cardiac activity during the second half of pregnancy, in some cases even much earlier [2, 3, 5]. We studied the ability of the fetal magnetocardiogram to non-invasively document and analyze fetal cardiac arrhtyhmias.

The Fetal Magnetocardiogram During Different Stages of Pregnancy

It has been demonstrated that the fetal magnetocardiogram can be recorded as early as the 13th week of pregnancy [2, 3]. In contrast to the fetal ECG recorded from the mother’s abdominal surface [1, 4], it remains detectable throughout late pregnancy and thus constitutes a non-invasive tool for the monitoring of intrauterine development. We studied the development of the fetal magnetocardiogram during pregnancy.