The early detection of congenital heart anomalies is critical for monitoring or prompt interventions, which can reduce the risks of congestive heart failure. This calls for sustained efforts to improve the existing tools and methodologies used for the non-invasive screening of the fetal heart structure and physiology. Recently, fetal magnetocardiography (fMCG) has emerged as an attractive technique for the in-utero assessment of the fetal cardiac electrophysiology, which can offer vastly superior capabilities to those, attainable by alternative methods. However, a significant concern consists in the large variability in position and orientation of the fetuses relative to the biomagnetic sensing system, which may introduce confounding effects on the morphology of the signals recorded over the maternal abdomen. The paucity of data on detailed fMCG signal morphology is a direct consequence of these confounds, since it is often difficult to explain the intersubject variations in signal distribution across the sensor array as being generated by fundamental differences in the cardiac electrophysiology, common inconsistencies in the fetal presentation or variable anatomy of the fetal- maternal unit. The current study will focus on the development of new strategies for augmenting the clinical utility the fMCG recordings, aiming at examining the cardiac activity in source space (rather than sensor space), where the above described physical factors become non-salient. The proposed approach relies on estimating the spatio temporal parameters of a multi-dipolar model of the fetal cardiac source using a recursive subspace scanning algorithm. To account for the geometry and conductivity properties of the feto-abdominal tissues, the study seeks establishing a versatile strategy for incorporating 3D anatomical information about the feto-abdominal volume conductor obtained from free-hand ultrasound images into the discrete formulation of the forward electromagnetic problem based on boundary element methods. The study will initiate the development of a longitudinal normative data-base for metrics derived from the reconstructed cardiac vectors in fMCG recordings of low-risk pregnancies. Fetal subjects with abnormal increase in the thickness of the free ventricular walls documented by ultrasound will also be studied to probe the sensitivity of the proposed approach for detecting hallmarks of abnormal heart electrophysiology. The investigation aims to represent a substantial contribution in promoting the role of fMCG for the non- invasive screening of fetal cardiac development and for the detection of electrophysiological abnormalities. The successful clinical validation of the methodology will highly recommend fMCG as an investigational tool for studying fetal cardiac electrophysiology in a broad range of conditions, particularly those associated with increased risk of ventricular hypertrophy, e.g. intra-uterine growth retardation, diabetes, pulmonary valve and aortic stenosis, closure of the ductus arteriosus, tetralogy of Fallot, or ventricular septal defect.
Congenital heart anomalies are more common than anomalies affecting any other organ;therefore, further advancement of the techniques used for fetal heart monitoring is likely to have a substantial impact upon public health. Fetal magnetocardiography (fMCG) offers unique capabilities for non-invasive screening of fetal cardiac electrophysiology;however, in order to attain clinical significance, fMCG must provide unequivocal and consistent measures of fetal cardiac activity. This investigation aims to represent a substantial contribution in promoting the role of fMCG for studying fetal cardiac development and electrophysiological abnormalities by means of advanced source reconstruction algorithms, which efficiently use the multichannel fMCG data and 3D ultrasound images of the feto-abdominal anatomy to provide reliable measures of fetal cardiac electrophysiology. The successful clinical validation of the methodology for fetuses with abnormal increase in ventricular wall thickness will highly recommend fMCG as an investigational tool for studying fetal cardiac electrophysiology in a broad range of conditions associated with increased risk of ventricular hypertrophy, e.g. intra-uterine growth retardation, diabetes, pulmonary valve and aortic stenosis, closure of the ductus arteriosus, tetralogy of Fallot, or ventricular septal defect.
| Tao, R; Popescu, E A; Drake, W B et al. (2013) Cardiac vectors in the healthy human fetus: developmental changes assessed by magnetocardiography and realistic approximations of the volume conductor. Physiol Meas 34:527-40 |
| Tao, Rong; Popescu, Elena-Anda; Drake, William B et al. (2012) The effect of volume conductor modeling on the estimation of cardiac vectors in fetal magnetocardiography. Physiol Meas 33:651-65 |
