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With the help of an extremely sensitive magnetic sensors array, magnetocardiography (MCG) can record magnetic field signals produced by the cardiac electrical activity. However, MCG is a very weak magnetic field signal, and tends to be overwhelmed by unsuppressed ambient magnetic noise. To address this issue, this work proposed a multi-channel MCG signals synchronously denoising method based on multivariate variational mode decomposition (MVMD) algorithm. Firstly, the MVMD algorithm extracted spatiotemporal correlation among channels and decomposed multi-channel signals into three-dimensional intrinsic mode functions (IMFs) matrix. By analyzing the time and frequency characteristics of each IMF, we figured out powerline interference (PLI), baseline wander (BW), and white Gauss noise (WGN), and then the sub-band filters removed the noise components before reconstruction. The correlation of three types of noises and MCG signals between channels were totally explored, and both simulated and experimental datasets verified the efficiency. The simulated results indicated that the average reconstruction error of the MCG signals is less than 1 pT. In the human MCG experiment, PLI and BW were reduced by approximately 60 dB and 20 dB, respectively, making the Q, R, and S waves clearly visible. Our work offers comprehensive solutions for denoising multi-channel MCG signals and significantly improves the denoising accuracy. • Synchronous filtering method for multi-channel MCG signals. • Introduction of spatiotemporal correlation among channels improves the accuracy of mode decomposition. • A comprehensive denoising method for MCG signals obtained from gradiometer or magnetic sensors array. [ABSTRACT FROM AUTHOR]

Wearable magnetocardiography (MCG) systems offer advantages such as flexible sensor distribution and higher signal strength than that of traditional rigid cardiac systems. However, the flexible nature of wearable cardiac magnetic systems presents challenges in acquiring accurate optically pumped magnetometer sensor positions and orientations. In this study, we developed a sensor-positioning indicator cap (SPIC) system. The SPIC used point-cloud data acquired through a structured light scanner to extract the three-axis orientations and positions of the sensors. Additionally, we proposed a novel combined branch and bound iterative closest point algorithm, which eliminates the need for initial alignment. Without requiring additional fiducial markers on the subject's body, the sensors were registered in the computed tomography (CT) coordinate system based on the clavicular region. We designed and fabricated a reference phantom with known sensor positions and orientations to evaluate the accuracy of our method. Experimental results demonstrated that after registration, the average position error for all sensors < 1 mm , with an average orientation error < 1 °. In addition, we conducted simulations to assess the impact of registration errors on MCG source localization. The results indicated that errors resulting from our proposed registration method would introduce an approximately 1 mm error in source localization. This study introduces a registration method facilitating the reusability of CT data in wearable MCG systems, thereby benefiting research in MCG source localization. [ABSTRACT FROM AUTHOR]

• Computational imaging of the heart source localization is demonstrated. • Forward problem of the heart is solved for Magnetocardiography. • A novel spatial matrix is proposed and constructed based on Vectorcardiography. • Multi start downhill simplex search is utilized to localize the cardiac sources. • Comparison of the proposed approach with the standard model is studied. The muscles of the heart are associated with the flow of currents on tissue in the volume conductor formed inside the human body. The electrical currents of the human heart generate a tiny magnetic field beyond the thorax surface. The functional waves generated in terms of the field are detected using Magnetocardiogram (MCG) at the detector level. One of the challenging tasks in the research area is to compute algorithms which help in visualizing/localizing the cardiac anomalies non-invasively at the heart level. In order to localize, a generic model based on prior assumptions is designed which is known as a forward problem. This model depicts the spatial relation between the heart locations and the detectors. In this paper, a novel method is proposed in the construction of the forward matrix; where the prior heart vectors are constrained with vectorcardiography (VCG) signals. The spatial matrix is subsequently used to estimate the desired position on the myocardium in an inverse way. To evaluate the model, several true prior dipoles are placed on desired positions of the heart each at a time and the inverse problem is solved using multi-start downhill simplex search. The spatial matrices are updated based on VCG during each movement of the test dipoles' positions in the inverse search. The inverse studies are computed and compared between the proposed and the existed methods for the entire cardiac cycle. The performance of the inverse model with unit VCG orientations exhibited an improvement of 3.027 ± 0.17 mm average localization error than the conventional one. [ABSTRACT FROM AUTHOR]

Magnetic field maps from (A) subjects without ischemia, showing a bipolar field map throughout the cardiac cycle, and (B) patients with acute coronary syndrome in whom a distorted, fragmented or multipolar field map characterizes active myocardial ischemia. Maps were recorded with a 15-channel magnetometry device and display the magnetic field distribution at the point of maximum rate of change between the Q and R peaks (QR) and between the R and S peaks (RS). Unlabelled Image The dipoles observed in subjects without ischemia are generally aligned in the same direction and have only a single positive (red) and single negative (blue) pole. The images from ischemic patients are generally more complex. A wider spread of angles and pole to pole distance, and the presence of more than two peaks are features that generally indicate ischemia. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • In this project, we are able to build critical part of the magnetic sensor that can sense weak magnetic field. • To detected maganetic field as a function of the interference that happens among the feeding currents in MCG. • Induced currents into SQUID sensor, of a two Josephson junctions connected in parallel. • To introduced the production of and characterization of superconducting thin films. Abstract In recent years, there has been an increase in the study of magnetocardiography (MCG), complementary to electrocardiography (ECG) research, with the purpose of increasing accuracy in the diagnosis of heart and brain pathologies. This research proposes the physical infrastructure of an advanced technology that can be used to obtain heart and brain signals from a specifically designed magnetic field. A generated magnetic sensor is proposed to sense weak magnetic fields in order to detect magnetic heart and brain activity, using interferometry methods. The method of detection of the magnetic field in the sensor, known as a superconducting quantum interference device (SQUID), is found in the interference that occurs during transmission of feeding currents, and the induced currents in the sensor. The sensor consists of two Josephson junctions, connected in parallel. This research presents a fabrication method and the characteristics of thin superconducting films, as an advance in the construction of a SQUID sensor. An ablation chamber is designed, and the deposition of the superconductor on a copper substrate is explored, to obtain thin films at lower cost. The results obtained show good characteristics of superconductivity which can produce a good quality magnetic sensor. There is an intention to further decrease the roughness of the material for the photolithography process. [ABSTRACT FROM AUTHOR]

Ventricular arrhythmias (VAs) with left bundle-branch-block and inferior axis morphology (LBBB-IA), suggestive of outflow tract (OT) origin, are a challenge in sports medicine because they can be benign or expression of a silent cardiomyopathy. Non-invasive classification is essential to plan ablation strategy if required. We aimed to evaluating magnetocardiographic (MCG) discrimination of OT-VAs site of origin (SoO). MCG and ECG data of 26 sports activity practitioners, with OT-VAs were analyzed. OT-VAs-SoO was classified with discriminant analysis (DA) of 8 MCG parameters and with invasively-validated ECG algorithms. MCG inverse source-localization merged with magnetic resonance (CMR) provided three-dimensional electro-anatomical imaging (MCG 3D-EAI). ECG classification was univocal in 73%. MCG-DA differentiated right ventricular OT from aortic sinus cusp VAs, with 94.7% accuracy. MCG 3D-EAI confirmed OT-VAs-SoO in CMR images. In cases undergoing ablation, MCG 3D-EAI was confirmed by CARTO 3D-EAI. MCG-DA improves non-invasive classification of OT-VAs-SoO. Further comparison with interventional results is required. [ABSTRACT FROM AUTHOR]

Purpose: Magnetocardiography (MCG) has been proposed as a noninvasive, diagnostic tool for risk-stratifying patients with acute myocardial infarction (AMI). This study evaluated whether MCG predicts long-term prognosis in AMI. Meterials and Methods: In 124 AMI patients (95 males, mean age 60±11 years), including 39 with ST-elevation myocardial infarction, a 64-channel MCG was performed within 2 days after AMI. During a mean follow-up period of 6.1 years, major adverse cardiac events (MACE) were evaluated. Results: MACE occurred in 31 (25%) patients, including 20 revascularizations, 8 deaths, and 3 re-infarctions. Non-dipole patterns were observed at the end of the T wave in every patients. However, they were observed at T-peak in 77% (24/31) and 54% (50/93) of patients with and without MACE, respectively (p=0.03). Maximum current, field map angles, and distance dynamics were not different between groups. In the multivariate analysis, patients with non-dipole patterns at T-peak had increased age- and genderadjusted hazard ratios for MACE (hazard ratio 2.89, 95% confidence interval 1.20-6.97, p=0.02) and lower cumulative MACE-free survival than those with dipole patterns (p=0.02). Conclusion: Non-dipole patterns at T-peak were more frequently observed in patients with MACE and were related to poor longterm prognosis. Thus, repolarization heterogeneity measured by MCG may be a useful predictor for AMI prognosis. [ABSTRACT FROM AUTHOR]

Background Lead V1 on electrocardiography (ECG) can detect the dominant frequency (DF) of atrial fibrillation (AF) in the right atrium (RA). Paroxysmal AF is characterized by a frequency gradient from the left atrium (LA) to the right atrium (RA). We examined the ability of magnetocardiography (MCG) to detect regional DFs in both the atria. Methods Study subjects comprised 18 consecutive patients referred for catheter ablation of persistent AF. An MCG system with 64 magnetic sensors was used to perform MCG in the frontal, lateral, and back planes prior to the ablation procedure in each patient. DF MCG and organization index (OI MCG ) were calculated using fast Fourier transformation. Intracardiac electrograms (ICEs) in both the atria and the coronary sinus (CS) were mapped at 17 sites. Regional DFs ICE were also determined. Results Mean LA DF ICE was higher than mean RA DF ICE (6.40±0.66 versus 6.16±0.80 Hz, P =0.03). DF MCG in the channel having the highest OI MCG was 6.61±0.88 Hz in the frontal plane, 6.52±0.64 Hz in the lateral plane, and 6.42±0.62 Hz in the back plane ( P =0.3). In each plane, DF MCG correlated with DF ICE at the RA appendage ( R =0.95, P <0.0001), the LA appendage ( R =0.91, P <0.0001), and the CS ( R =0.93, P <0.0001). DF ECG in V5 modestly correlated with DF ICE at the LA appendage ( R =0.82, P <0.0001). Conclusions MCG could more precisely detect the DFs in the LA and the CS than ECG. However, the usefulness of pre-procedural detection of the AF frequency gradient for ablation therapy needs to be evaluated in future prospective studies. [ABSTRACT FROM AUTHOR]

The signal preprocessing is prerequisite for reduction of noise and for better estimation of sources from the measured field distribution of multichannel data, since different measurement channels may be contaminated by different types of artifacts and noise. Toward this, we use a combination of independent component analysis (ICA) and ensemble empirical mode decomposition (EEMD) to denoise the multichannel magnetocardiography (MCG) data. In this technique, MCG time series data is first subjected to ICA to obtain the statistically independent components (ICs) and subsequently the EEMD-interval threshold based denoising is applied to the ICs prior to the reconstruction of the signal. We compare the results obtained from EEMD-ICA with those obtained using the conventional ICA alone and also using the wavelet enhanced ICA (wICA). We illustrate the effect of these denoising techniques on the pseudo current density (PCD) maps, which aid in visualizing the source location. The results obtained from the EEMD-ICA are seen to be decidedly superior compared to those obtained by ICA alone and wICA methods. [ABSTRACT FROM AUTHOR]

Recently, several new beamformers have been introduced for reconstruction and localization of neural sources from EEG and MEG. Although studies have compared the accuracy of beamformers for localization of strong sources in the brain, a comparison of new and conventional beamformers for time-course reconstruction of a desired source has not been previously undertaken. In this study, 8 beamformers were examined with respect to several parameters, including variations in depth, orientation, magnitude, and frequency of the simulated source to determine their (i) effectiveness at time-course reconstruction of the sources, and (ii) stability of their performances with respect to the input changes. The spatial and directional pass-bands of the beamformers were estimated via simulated and real EEG sources to determine spatial resolution. White-noise spatial maps of the beamformers were calculated to show which beamformers have a location bias. Simulated EEG data were produced by projection via forward head modelling of simulated sources onto scalp electrodes, then superimposed on real background EEG. Real EEG was recorded from a patient with essential tremor and deep brain implanted electrodes. Gain – the ratio of SNR of the reconstructed time-course to the input SNR – was the primary measure of performance of the beamformers. Overall, minimum-variance beamformers had higher Gains and superior spatial resolution to those of the minimum-norm beamformers, although their performance was more sensitive to changes in magnitude, depth, and frequency of the simulated source. White-noise spatial maps showed that several, but not all, beamformers have an undesirable location bias. [ABSTRACT FROM AUTHOR]

Abstract: Magnetocardiography (MCG) using superconducting quantum interference devices (SQUIDs) is a new medical diagnostic tool measuring biomagnetic signals that are generated by the electrical activity of the human heart. This technique is completely passive, contactless, and it has an advantage in the early diagnosis of heart diseases. We developed the first unshielded four-channel MCG system based on low-Tc DC SQUIDs in China. Instead of using a costly magnetically shielded room, the environmental noise suppression was realized by using second-order gradiometers and three-axis reference magnetometer. The measured magnetic field resolution of the system is better than 1 pT, and multi-cycle human heart signals can be recorded directly. Also, with the infrared positioning system, 48 points data collection can be realized by moving the non-magnetic bed nine times. [Copyright &y& Elsevier]

Abstract: In this paper, we propose a new method for monitoring the position of marker coils. The marker coil is used for indicating spatial relationship between subject''s body and magnetic sensor arrays in biomagnetic measurements, such as magnetoencephalography (MEG) and magnetocardiography (MCG). We developed a real-time marker coil position monitoring system combined with a conventional MEG system. In order to achieve simultaneous measurement of MEG signals and marker signals, we separated their frequency bands. The frequency bands of flux-locked loop (FLL) circuits were separated into three parts by three integrators; low-band, mid-band, and high-band. The second and third bands were assigned for MEG signals and marker signals, respectively. This method can avoid the crosstalk of the marker signals to MEG signals. Marker signals were generated from five marker coils driven by five independent sinusoidal current generators. These signals were continuously measured by the high-band of FLL, and then the coils were localized by FFT processing and solving inverse problem. We succeeded in displaying the localized coil position on a PC monitor once per second in real-time. [Copyright &y& Elsevier]

Abstract: The new line of dc-SQUID-based magnetocardiographic (MCG) systems (named as the “MAG-SCAN”-family) is designed, fabricated and tested. These systems are intended for routine MCG investigations of patients at conditions of real clinical electrophysiological labs. The “MAG-SCAN”-family includes the line of MCG devices compatible in terms of hardware and software with number of measuring channels from 1 to 36. Experimental prototypes of 7- and 9-channel MCG-systems (the models “MAG-SCAN-07” and “MAG-SCAN-09” fabricated at CRYOTON Co. Ltd.) were installed in a few hospitals of Moscow city and operated in an unshielded environment of usual clinical labs. Well balanced second-order gradiometers have been used for MCG data recording. They demonstrated an intrinsic noise level better than 5 fT/√Hz. The total noise level of about 20-40 fT/√Hz was measured at urban conditions of Moscow city. The package of special software (named as the “SOFTMAG”) was developed as two autonomous subsystems that allow the preprocessing of the heart magnetic signals and the spatio-temporal analysis of the field characteristics and the field sources. The software employs the algorithms for the analysis and estimation of the spatio-temporal characteristics of the heart magnetic field and the correspondent electrical currents distributions. More than 2000 investigations of different volunteers including healthy persons, patients with high blood-pressure, ischemic disease (IHD), chronic obstructive pulmonary disease (COPD) and bronchial asthma (BA) were carried out and sets of MCG-parameters specific for each group were found. [Copyright &y& Elsevier]

Background: Congenital long-QT syndrome (LQTS) may present during fetal development and can be life-threatening. The molecular mechanism for the unusual early onset of LQTS during fetal development is unknown. Objective: We sought to elucidate the molecular basis for severe fetal LQTS presenting at 19 weeks'' gestation, the earliest known presentation of this disease. Methods: Fetal magnetocardiography was used to demonstrated torsades de pointes and a prolonged rate-corrected QT interval. In vitro electrophysiological studies were performed to determine functional consequences of a novel SCN5A mutation found in the fetus. Results: The fetus presented with episodes of ventricular ectopy progressing to incessant ventricular tachycardia and hydrops fetalis. Genetic analysis disclosed a novel, de novo heterozygous mutation (L409P) and a homozygous common variant (R558 in SCN5A). In vitro electrophysiological studies demonstrated that the mutation in combination with R558 caused significant depolarized shifts in the voltage dependence of inactivation and activation, faster recovery from inactivation, and a 7-fold higher level of persistent current. When the mutation was engineered in a fetal-expressed SCN5A splice isoform, channel dysfunction was markedly potentiated. Also, R558 alone in the fetal splice isoform evoked a large persistent current, and hence both alleles were dysfunctional. Conclusion: We report the earliest confirmed diagnosis of symptomatic LQTS and present evidence that mutant cardiac sodium channel dysfunction is potentiated by a developmentally regulated alternative splicing event in SCN5A. Our findings provide a plausible mechanism for the unusual severity and early onset of cardiac arrhythmia in fetal LQTS. [Copyright &y& Elsevier]

Abstract: A SQUID magnetometer system with three-dimensional(3-D) second-order gradiometer was used to measure the magnetocardiograms(MCG) for the normal subject and the patient with myocardial infarction (MI). In order to discuss the activities of the heart between the normal subject and the patient with MI, we have presented the isoenergy contour maps to evaluate the spatial energy distribution (SED) of the QRS complex at different scale. Being different from the normal subject, the patient with MI represented different the pattern of the SED in various frequency band for the ST segment of the QRS complexof Bx, By, and Bz components. It is helpful to evaluate the patient with MI using the isoenergy contour maps of 3-D MCG. [Copyright &y& Elsevier]

Abstract: A SQUID magnetometer system with three-dimensional(3-D) second-order gradiometer was used to measure the magnetocardiograms(MCG) for the normal subject and the patient with myocardial infarction (MI). The multiple sources were estimated using the single current dipole model based on the 3-D MCG measurement. The difference between the normal subject and the patient with MI was discussed in the conduction pathways. It is helpful to discriminate the location and the direction of multiple sources based on combining Bz component with Bx and By components. The 3-D MCG measurement may be more efficient than the 1-D MCG measurement in estimating the multiple sources. [Copyright &y& Elsevier]

Abstract: Introduction: The purpose of our study was to prove the existence of the U wave using magnetocardiograms (MCGs). Methods: The 31-channel MCGs of 25 healthy volunteers were recorded. The onset of the U wave was defined by newly developed spatial correlation analysis; and the end, by different approaches. Results: A U wave could be proved in all volunteers. In 10 volunteers (heart rate, 57 ± 19 beats/min) in whom the U wave was found to be separated from the following P wave, the U wave''s end could be determined as a threshold value (U wave duration, 310 ± 24 milliseconds). In 15 volunteers (heart rate, 70 ± 38 beats/min), the end of the U waves was concealed by a continuous transition of the U waves into the following P waves. Conclusions: The U wave seems to be a regular phenomenon and has a distinct spatiotemporal assembly. [Copyright &y& Elsevier]

Ischemic heart disease (IHD) is one of the leading causes of death in the general population. Ischemia induces changes in the electrophysiologic properties of the myocardium that sometimes cannot be detected with rest ECG, which has a relatively low sensitivity. Magnetocardiography (MCG) which records the magnetic fields generated by the heart, is reported more sensitive for measuring myocardial electric activity. Many analyzing methods using MCG for the diagnosis of IHD are reported. Those methods can be summarized as follows: [1.] magnetic measurement of ST and TQ segment shift, [2.] spatial dispersion of the magnetocardiographically determined QT intervals (QT dispersion), [3.] ST current angle rotation of magnetic field (isomagnetic map) at rest or in exercise magnetocardiography, [4.] analyzing current arrow map during ventricular repolarization, and [5.] analyzing the integral values of reporalization In this review we will given an overview of the current status of MCG methods for the diagnosis of IHD. [Copyright &y& Elsevier]

Abstract: We verified the significance of 3-dimensional (3D) spectral mapping during atrial fibrillation (AFIB) using a 64-channel magnetocardiogram (MCG). The study consisted of 16 patients with valvular heart disease who had chronic AFIB. All 16 patients had surgical pulmonary vein (PV) isolation followed by valvular repair. We performed spectral mapping by fast Fourier transform analysis in nonaveraged 64-channel MCG data. The 3D spectral map was superimposed on a 3D heart polygon. At 1 year after surgical PV isolation for AFIB, followed by valve repair, 7 patients had restoration to sinus rhythm, and 9 patients remained in persistent AFIB. The preoperative mean 3D frequency of AFIB was 6.1 ± 0.9 Hz in patients with restored sinus rhythm and 7.2 ± 0.7 Hz in patients with sustained AFIB after PV isolation (P = .02). In addition, the preoperative 3D spectrum was distributed on the right side of the heart in patients with persistent AFIB. In conclusion, 3D spectral mapping using 64-channel MCG may represent a meaningful noninvasive strategy for patients with AFIB who receive an interventional procedure. [Copyright &y& Elsevier]

The article presents research on the effect of dietary polyunsaturated fatty acids with direct renin inhibition on the electrophysiological remodeling in angiotensin II induced cardiac injury. Laboratory experiments with rats showed reductions in arrhythmia, microphage infiltration, and fibrosis. Despite cardiac hypertrophy, electrical remodeling was improved.

Abstract: Magnetocardiography (MCG) is a method complementary to electrocardiography (ECG). We examined recording and reproducibility of atrial depolarization signal by MCG. Multichannel MCG over anterior chest and orthogonal 3-lead ECG were recorded in 9 patients who had paroxysmal lone atrial fibrillation and in 10 healthy subjects in duplicate at least 1 week apart. Data were averaged using atrial wave template and high-pass filtered at 25, 40, and 60 Hz. Atrial signal duration with automatic detection of onset and offset and root mean square amplitudes of the last portion of atrial signal were determined. Coefficient of variation of atrial signal duration by MCG at 40 Hz was 3.3% and difference between the measurements was 3.5 milliseconds on average. The corresponding figures obtained by signal-averaged ECG (SAECG) were 6.1% and 6.9 milliseconds. Coefficient of variation for root mean square of the last 40 milliseconds of atrial signal were 16% in MCG and 17% in SAECG. Reproducibility was best at 40-Hz filter and similar in patients and healthy subjects. In conclusion, the reproducibility of atrial signal variables in MCG is adequate and somewhat better than in SAECG and equal in patients with lone atrial fibrillation and healthy subjects. Magnetocardiography seems to be a potentially valuable method to evaluate features of atrial depolarization in patient studies. [Copyright &y& Elsevier]

Abstract: Here, we present a rare case of fetal bradyarrhythmia following magnesium sulfate therapy for preterm labor. After we switched treatment from ritodrine hydrochloride to magnesium sulfate at 25 weeks' gestation, the fetal heart rate dropped from 150bpm to 80–100bpm. Fetal echocardiography and magnetocardiography indicated bigeminy and trigeminy of blocked premature atrial contractions. It is well known that magnesium sulfate decreases the baseline and variability of fetal heart rate. Studies have reported a substantial decrease of 2–15bpm in the baseline fetal heart rate, and magnesium has various effects on fetal heart rate patterns with a lower baseline fetal heart rate within the normal range of 110–160bpm. This is the first report of magnesium sulfate-induced fetal bradyarrhythmia by prolongation of the refractory period of the atrioventricular node in the case of blocked premature atrial contractions. Clinicians should consider fetal bradyarrhythmia when the baseline fetal heart rate drops to <100bpm after magnesium sulfate administration. [Copyright &y& Elsevier]

Background: Long QT syndrome (LQTS) is a leading cause of sudden cardiac death in early life and has been implicated in ≈10% of sudden infant deaths and unexplained stillbirths. The purpose of our study was to use fetal magnetocardiography to characterize the electrophysiology and rhythm phenotypes of fetuses with de novo and inherited LQTS variants and identify risk factors for sudden death before birth.Methods: We reviewed the fetal magnetocardiography database from the University of Wisconsin Biomagnetism Laboratory for fetuses with confirmed LQTS. We assessed waveform intervals, heart rate, and rhythm, including the signature LQTS rhythms: functional 2° atrioventricular block, T-wave alternans, and torsade de pointes (TdP).Results: Thirty-nine fetuses had pathogenic variants in LQTS genes: 27 carried the family variant, 11 had de novo variants, and 1 was indeterminate. De novo variants, especially de novo SCN5A variants, were strongly associated with a severe rhythm phenotype and perinatal death: 9 (82%) showed signature LQTS rhythms, 6 (55%) showed TdP, 5 (45%) were stillborn, and 1 (9%) died in infancy. Those that died exhibited novel fetal rhythms, including atrioventricular block with 3:1 conduction ratio, QRS alternans in 2:1 atrioventricular block, long-cycle length TdP, and slow monomorphic ventricular tachycardia. Premature ventricular contractions were also strongly associated with TdP and perinatal death. Fetuses with familial variants showed a lower incidence of signature LQTS rhythm (6/27=22%), including TdP (3/27=11%). All were live born.Conclusions: The malignancy of de novo LQTS variants was remarkably high and demonstrate that these mutations are a significant cause of stillbirth. Their ability to manifest rhythms not known to be associated with LQTS increases the difficulty of echocardiographic diagnosis and decreases the likelihood that a resultant fetal loss is attributed to LQTS. Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03047161. [ABSTRACT FROM AUTHOR]

Abstract: Background: We hypothesized that fetuses at risk for sudden death may have abnormal conduction or depolarization, ischemia, or abnormal heart rate variability (HRV) detectable by magnetocardiography. Methods: Using a 37-channel biomagnetometer, we evaluated 3 groups of fetuses at risk for sudden death: group 1, critical aortic stenosis (AS); group 2, arrhythmias; and group 3, heart failure and in utero demise. Five to 10 recordings of 10-minute duration were recorded, and signal was averaged to determine rhythm, conduction intervals, HRV, and T-wave morphology. Results: In group 1, 2 of 3 had atrial and ventricular strain patterns. In (n = 53) group 2, 15% had prolonged QTc and 17% had T-wave alternans (TWA). Of 23 group 2 fetuses with atrioventricular block, 74% had ventricular ectopy, 21% had junctional ectopic tachycardia, and 29% had ventricular tachycardia. Group 3 (n = 2) had abnormal HRV and TWA. Conclusion: Repolarization abnormalities, unexpected arrhythmias, and abnormal HRV suggest an arrhythmogenic mechanism for “sudden cardiac death before birth.” [Copyright &y& Elsevier]

Objective: The purpose of this study was to compare cardiac dynamics of high-risk and low-risk fetuses using beat to beat variability. Study Design: This study obtained 214 fetal magnetocardiography recordings from a group of high-risk fetuses with maternal conditions associated with placental insufficiency with the risk of developing intrauterine growth restriction or were already diagnosed with intrauterine growth restriction. For purpose of comparison, another 136 recordings were obtained from low-risk fetuses. The cardiac beat-to-beat intervals computed as RR intervals were analyzed from both groups using the mean and median interval, standard deviation of normal-to-normal intervals, root mean square of the successive differences, and the fraction of the normal-to-normal intervals (pNNx) that differ by more than the chosen tolerance level of ‘x’ milliseconds from the previous normal-to-normal intervals. Tests for significance between high-risk and low-risk fetuses were calculated using an independent samples t test within the following gestational age groups, 27-30 weeks, 31-35 weeks, and 36-40 weeks. Results: The root mean square of the successive differences, and the pNNx showed a significant difference between the low-risk and high-risk fetuses in the 31-35-week and the 36-40-week divisions. In the 31-35-week age division, low-risk fetuses had significantly lower root mean square of the successive differences, and pNN values than the high risk, but in the 36-40-week division, the low-risk fetuses had significantly higher root mean square of the successive differences, and pNN values. Conclusion: Cardiac dynamics for fetuses of mothers at risk for placental insufficiency mature quicker than fetuses not at risk for placental insufficiency. [Copyright &y& Elsevier]

Abstract: New “magnetic” technologies for intracardiac three-dimensional electroanatomical imaging (3D-EAI) have been recently developed, which have proven useful to localize the arrhythmogenic targets, to improve the outcome of ablation procedures and to reduce patient irradiation. However their 3D imaging capability cannot be used for preoperative localization of arrhythmogenic substrates. Magnetocardiographic mapping (MCG) is a more feasible and reproducible method to provide non-invasive 3D-EAI of cardiac sources. MCG detection and 3D study of arrhythmias can be enhanced by simultaneous electrophysiologic study with trans-esophageal atrial pacing and by combining MCG with minimally invasive single-catheter, multiple monophasic action potential recording, which provides a better understanding of local arrhythmogenic mechanisms underlying abnormal MCG patterns. MCG is also feasible for non-fluoroscopic imaging of amagnetic catheters in the heart. Furthermore providing 3D numerical coordinates of arrythmogenic targets, MCG could be used to program robotic magnetic navigation and to automatically guide ablation catheters or aimed endomyocardial biopsy. [Copyright &y& Elsevier]