Low Baseline Fetal Heart Rate Leads to Diagnosis of Long QT Syndrome Type 1.

A low baseline fetal heart rate at 20 weeks' gestation was detected in a fetus without cardiac structural anomalies. Fetal echocardiography and magnetocardiography were used to diagnose congenital long QT syndrome. It was confirmed in the neonate, and the same pathogenic variant in was subsequently identified in the mother.

Fetal Congenital Complete Heart Block: A Rare Case with an Extremely Low Ventricular Rate and Review of Current Management Strategies.

Congenital complete heart block (CCHB) is associated with high intrauterine and post-natal mortality. Prenatal detection and management, as well as appropriate delivery planning, may improve the outcomes in CCHB. We describe a rare case of CCHB that initially presented with fetal ascites and high-grade second-degree heart block noted on fetal echocardiography.

A Small Scale Optically Pumped Fetal Magnetocardiography System.

Introduction: Fetal magnetocardiography (fMCG) is considered the best technique for diagnosis of fetal arrhythmia. It is superior to more widely used methods such as fetal, fetal electrocardiography, and cardiotocography for evaluation of fetal rhythm. The combination of fMCG and fetal echocardiography can provide a more comprehensive evaluation of fetal cardiac rhythm and function than is currently possible.

Ferrite Shield to Enhance the Performance of Optically Pumped Magnetometers for Fetal Magnetocardiography.

Fetal magnetocardiography (fMCG) has proven to be an important tool for the prenatal monitoring of electrical cardiac activity; however, the high cost of superconducting quantum instrumentation (SQUID) poses a limitation for the dissemination of fMCG as a routine clinical technique. Recently, optically pumped magnetometers (OPMs) operating within person-sized, cylindrical shields have made fMCG more practical, but environmental magnetic interference entering through the shield opening substantially degrades the quality of fMCG signals. The goal of this study was to further attenuate these interferences by placing the OPM array within a small ferrite shield.

Contribution of Fetal Magnetocardiography to Diagnosis, Risk Assessment, and Treatment of Fetal Arrhythmia.

Background Fetal echocardiography has been the mainstay of fetal arrhythmia diagnosis; however, fetal magnetocardiography (fMCG) has recently become clinically available. We sought to determine to what extent fMCG contributed to the precision and accuracy of fetal arrhythmia diagnosis and risk assessment, and in turn, how this altered pregnancy management. Methods and Results We reviewed fMCG tracings and medical records of 215 pregnancies referred to the Biomagnetism Laboratory, UW-Madison, over the last 10 years, because of fetal arrhythmia or risk of arrhythmia.

Repolarization Predictors of Fetal Long QT Syndrome.

Background: Diagnosis of fetal long QT syndrome (LQTS) using fetal magnetocardiography (fMCG) is straightforward in cases of overt QTc prolongation accompanied by LQTS rhythms; however, cases of isolated QTc prolongation can be challenging.

Objective: To characterize repolarization in normal and phenotype-positive LQTS fetuses with the goal of utilizing additional parameters of repolarization to improve the accuracy of fMCG diagnosis of LQTS.

Methods: FMCG recordings were taken from 37 phenotype-positive fetuses with confirmed LQTS and 132 normal controls.

Genotype Predicts Outcomes in Fetuses and Neonates With Severe Congenital Long QT Syndrome.

Objectives: This study sought to determine the relationship between long QT syndrome (LQTS) subtype (LTQ1, LTQ2, LTQ3) and postnatal cardiac events (CEs).

Background: LQTS presenting with 2:1 atrioventricular block or torsades de pointes in the fetus and/or neonate has been associated with risk for major CEs, but overall outcomes and predictors remain unknown.

Methods: A retrospective study involving 25 international centers evaluated the course of fetuses/newborns diagnosed with congenital LQTS and either 2:1 atrioventricular block or torsades de pointes.

Dynamics of the use of magnetocardiography in the study of the cardiac conduction system of the chick embryo.

Introduction: Human fetal magnetocardiography (fMCG) has been done for several decades to evaluate fetal arrhythmias using a superconducting quantum interference device (SQUID) magnetometer, but there is little work in embryonic/fetal animal models. This study uses an optically-pumped magnetometer (OPM) to obtain an fMCG in the chick embryo.

Methods: White Leghorn chick embryos were examined from incubation Day #10-19.

Noninvasive Fetal Electrocardiography in the Diagnosis of Long QT Syndrome: A Case Series.

Introduction: Early detection and monitoring for malignant arrhythmias is fundamental to prenatal care in long QT syndrome (LQTS). Recently, we studied the feasibility of isolating the fetal electrocardiogram (fECG) and measuring electrocardiographic intervals with a noninvasive fECG device using blind source separation with reference signal. Our aim was to evaluate the ability of fECG to diagnose LQTS.

Complex and Novel Arrhythmias Precede Stillbirth in Fetuses With De Novo Long QT Syndrome.

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.

Low-Cost Fetal Magnetocardiography: A Comparison of Superconducting Quantum Interference Device and Optically Pumped Magnetometers.

Background Fetal magnetocardiography (fMCG) is a highly effective technique for evaluation of fetuses with life-threatening arrhythmia, but its dissemination has been constrained by the high cost and complexity of Superconducting Quantum Interference Device (SQUID) instrumentation. Optically pumped magnetometers (OPMs) are a promising new technology that can replace SQUIDs for many applications. This study compares the performance of an fMCG system, utilizing OPMs operating in a person-sized magnetic shield, to that of a conventional fMCG system, utilizing SQUID magnetometers operating in a magnetically shielded room.

Fetal magnetocardiogram waveform characteristics.

Background: Fetal magnetocardiography (fMCG) is the most direct and precise method of assessing fetal rhythm and conduction. Although the utility of fMCG for evaluation of fetuses with serious arrhythmia is generally acknowledged, many aspects of fetal rhythm and conduction are relatively unstudied.

Objective: To record fMCG in a large group of normal fetuses in order to provide a more comprehensive evaluation of fMCG waveform characteristics, including waveform intervals, amplitudes, and morphology.

Fetal QT Interval Estimation Using Sequential Hypothesis Testing.

: Recent studies utilizing fetal magnetocardiography have demonstrated the efficacy of corrected QT interval (QTc) measurement for in utero diagnosis and prognosis of long QT syndrome, a leading cause of sudden death in early life. The objective of the study was to formulate and test a novel statistical estimation method to detect the end of the fetal T-wave and thereby improve the accuracy of fetal QT interval measurement. : To detect the end of the T-wave, we apply a sequential composite hypothesis test to decide when the T-wave has returned to baseline.

Importance of Fetal Arrhythmias to the Neonatologist and Pediatrician.

Sudden, unexplained death during the perinatal period remains a major, longstanding challenge. Recent advances in diagnostic techniques and genetic testing has provided evidence that a significant fraction of these deaths may result from lethal cardiac arrhythmias. In this paper, we review current methods of diagnosing arrhythmia in the fetus and strategies for management of life-threatening arrhythmia throughout the perinatal period, including transitional care at the time of delivery.

The natural history of fetal long QT syndrome.

Introduction: Fetal magnetocardiography (fMCG), the magnetic analog of ECG, has provided invaluable insight into the mechanisms of fetal arrhythmias. In the past 15years, we have evaluated over 300 fetuses with arrhythmia by fMCG. We review the unique characteristics and natural history of the long QT syndrome (LQTS) rhythms.

Fetal Atrial Flutter: Electrophysiology and Associations With Rhythms Involving an Accessory Pathway.

Background: Atrial flutter (AFl) accounts for up to one third of all fetal tachyarrhythmias and can result in premature delivery, hydrops, and fetal death in 10% of cases; however, the electrophysiology of AFl in utero is virtually unstudied.

Methods And Results: In this observational study, we reviewed 19 fetal magnetocardiography studies from 16 fetuses: 15 fetuses (21-38 weeks' gestation) referred with an echocardiographic diagnosis of AFl and 1 fetus (20 weeks' gestation) referred with a diagnosis of tachycardia that was shown by fetal magnetocardiography to have transient AFl in addition to atrioventricular reciprocating tachycardia. Thirteen fetuses showed AFl during the fetal magnetocardiography session, including 4 that presented prior to the third trimester.

Segmented independent component analysis for improved separation of fetal cardiac signals from nonstationary fetal magnetocardiograms.

Fetal magnetocardiograms (fMCGs) have been successfully processed with independent component analysis (ICA) to separate the fetal cardiac signals, but ICA effectiveness can be limited by signal nonstationarities due to fetal movements. We propose an ICA-based method to improve the quality of fetal signals separated from fMCG affected by fetal movements. This technique (SegICA) includes a procedure to detect signal nonstationarities, according to which the fMCG recordings are divided in stationary segments that are then processed with ICA.