Fetal magnetocardiography (fMCG): moving forward in the establishment of clinical reference data by advanced biomagnetic instrumentation and analysis

Abstract

Cardiotocography and echocardiography are currently standard for fetal heart monitoring. However, both do not provide adequate temporal resolution to measure fetal cardiac time intervals and detect arrhythmias, which can occur during normal sinus rhythm. Fetal magnetocardiography (fMCG) is a non-invasive technique measuring magnetic signals generated by fetal heart activity. Most fMCG devices are installed in research institutions limiting the implementation of this method in a clinical setting. Several institutions made a step forward by installing devices, in particular for fetal investigations, in hospital sites to evaluate the clinical benefit. Based on instrumentation differences which can affect signal quality, there is still no established reference database for fetal cardiac time intervals. A new magnetograph dedicated to fetal recordings was implemented with improved patient comfort. The setting was optimized to establish a standard. A total of 103 healthy fetuses starting as early as possible after the first trimester were recorded and fMCG values of cardiac time intervals were compared to former studies. Data allowed high and reliable detection for all fMCG components starting at 17 weeks. The data were comparable to fMCG multicenter studies, fetal electrocardiography and neonatal ECG results and could serve as a database of norm values for further investigation of fetal arrhythmias.

Development and application of an automated extraction algorithm for fetal magnetocardiography – normal data and arrhythmia detection

“…The fCTI results, achieved using the automated version, were compared to the results for the current reference values of normal CTIs based on fMCG or fECG measurements. Our results were comparable to our own previous study [10] and to data from other groups [3,10,11,16,20,22]. In comparison to other studies, only 15 differences with respect to the lengths of the T waves at late gestational ages were observed [10,11].…”

“…Our results were comparable to our own previous study [10] and to data from other groups [3,10,11,16,20,22]. In comparison to other studies, only 15 differences with respect to the lengths of the T waves at late gestational ages were observed [10,11]. There is a relatively large range of reported T-wave values in different studies [3,10,11] and even in single studies based on different observers.…”

“…In comparison to other studies, only 15 differences with respect to the lengths of the T waves at late gestational ages were observed [10,11]. There is a relatively large range of reported T-wave values in different studies [3,10,11] and even in single studies based on different observers. Taking into account that the T wave usually has a weak signal, the problem is most likely related to the definition of the onset and offset of the T waves.…”

“…To reliably evaluate fetal signals, several analysis procedures have been proposed, including eigenvector-based spatial filtering [1], an orthogonal projection (OP) [13,23], and independent component analysis (ICA) [4,5]. Previous studies [10,11] have shown a reliable extraction method for fetal cardiac time intervals (fCTIs) using OP. Until now, all approaches for the extraction of fetal heart signals have been based on user interventions, e.g., for OP, a template for the QRS complex had to be selected.…”

Antenatal architecture and activity of the human heart

“…They may also be used as an experimental method to quantitatively investigate the mechanisms of arrhythmia and their pharmacological control, and to pre-screen the actions of pharmacological agents on the electrical activity of the heart. Coupled with high-resolution fECG or f-magnetocardiography [32], computational modelling of the electrophysiology of the developing human foetal heart could contribute to the development of a foetal cardiology based on fECGs, which can be recorded from the eighth week of pregnancy and their intervals can be extracted from week 12. Here, we have used these fECG intervals to inform preliminary models of foetal cell electrophysiology.…”