The Experts below are selected from a list of 1023 Experts worldwide ranked by ideXlab platform
Ronald T. Wakai - One of the best experts on this subject based on the ideXlab platform.
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dynamics of the use of Magnetocardiography in the study of the cardiac conduction system of the chick embryo
Birth defects research, 2020Co-Authors: Michael A Schellpfeffer, Janette F. Strasburger, Sarah Strand, W J Lutter, Oswaldo Baffa, Tan Phan, Ronald T. WakaiAbstract: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. Different examination chambers were tested to optimize embryonic thermal stability and magnetic signal acquisition. All examinations were done with magnetic shielding. The OPM sensors were placed next to the egg shell. The embryo's position was localized by transilluminating the intact egg or ultrasound imaging the egg with an open air cell to optimize sensor placement. The raw data for each embryo was postprocessed to obtain a fMCG composite waveform. Results fMCG's were obtained in embryos from Day #12 to 19. The best success with intact eggs was obtained using five sensors; one at the bottom and four around the lower perimeter of the egg at 90° intervals with the egg oriented vertically and the air cell up. Using ultrasound imaging with the air cell open only two sensors were necessary, one at the bottom and one laterally next to the embryo. fMCGs were analyzed for heart rate and rhythm, each portion of the PQRST waveform, and the PR interval, QRS complex, RR interval, and QT interval. Conclusions This study validates the chick embryo as an animal model to study in a longitudinal and noninvasive fashion the fetal cardiac conduction system by using OPM Magnetocardiography.
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low cost fetal Magnetocardiography a comparison of superconducting quantum interference device and optically pumped magnetometers
Journal of the American Heart Association, 2019Co-Authors: Sarah Strand, Vishal Shah, Janette F. Strasburger, W J Lutter, Oswaldo Baffa, Ronald T. WakaiAbstract: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 a...
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characterizing atomic magnetic gradiometers for fetal Magnetocardiography
Review of Scientific Instruments, 2019Co-Authors: I A Sulai, Ronald T. Wakai, Zack Deland, Michael D Bulatowicz, C P Wahl, T G WalkerAbstract:Atomic magnetometers (AMs) offer many advantages over superconducting quantum interference devices due to, among other things, having comparable sensitivity while not requiring cryogenics. One of the major limitations of AMs is the challenge of configuring them as gradiometers. We report the development of a spin-exchange relaxation free vector atomic magnetic gradiometer with a sensitivity of 3 fT cm−1 Hz−1/2 and common mode rejection ratio >150 in the band from DC to 100 Hz. We introduce a background suppression figure of merit for characterizing the performance of gradiometers. It allows for optimally setting the measurement baseline and for quickly assessing the advantage, if any, of performing a measurement in a gradiometric mode. As an application, we consider the problem of fetal Magnetocardiography (fMCG) detection in the presence of a large background maternal MCG signal.
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characterizing atomic magnetic gradiometers for fetal Magnetocardiography
arXiv: Instrumentation and Detectors, 2019Co-Authors: I A Sulai, Ronald T. Wakai, Zack Deland, Michael D Bulatowicz, C P Wahl, T G WalkerAbstract:Atomic magnetometers (AMs) offer many advantages over superconducting quantum interference devices (SQUIDs) due to, among other things, having comparable sensitivity while not requiring cryogenics. One of the major limitations of AMs is the challenge of configuring them as gradiometers. We report the development of a spin-exchange relaxation free (SERF) vector atomic magnetic gradiometer with sensitivity of $3\, \rm{fT} \,{cm}^{-1}{Hz}^{-1/2}$ and common mode rejection ratio (CMRR) $> 150$ in the band from DC to 100 Hz. We introduce a background suppression figure of merit for characterizing the performance of gradiometers. It allows for optimally setting the measurement baseline, and for quickly assessing the advantage, if any, of performing a measurement in gradiometric mode. As an application, we consider the problem of fetal Magnetocardiography (fMCG) detection in the presence of a large background maternal MCG signal.
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a compact high performance atomic magnetometer for biomedical applications
Physics in Medicine and Biology, 2013Co-Authors: Vishal Shah, Ronald T. WakaiAbstract:We present a highly sensitive room-temperature atomic magnetometer (AM), designed for use in biomedical applications. The magnetometer sensor head is only 2 × 2 × 5 cm3 and is constructed using readily available, low-cost optical components. The magnetic field resolution of the AM is <10 fT Hz–1/2, which is comparable to cryogenically cooled superconducting quantum interference device (SQUID) magnetometers. We present side-by-side comparisons between our AM and a SQUID magnetometer, and show that equally high quality magnetoencephalography and Magnetocardiography recordings can be obtained using our AM.
T G Walker - One of the best experts on this subject based on the ideXlab platform.
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characterizing atomic magnetic gradiometers for fetal Magnetocardiography
Review of Scientific Instruments, 2019Co-Authors: I A Sulai, Ronald T. Wakai, Zack Deland, Michael D Bulatowicz, C P Wahl, T G WalkerAbstract:Atomic magnetometers (AMs) offer many advantages over superconducting quantum interference devices due to, among other things, having comparable sensitivity while not requiring cryogenics. One of the major limitations of AMs is the challenge of configuring them as gradiometers. We report the development of a spin-exchange relaxation free vector atomic magnetic gradiometer with a sensitivity of 3 fT cm−1 Hz−1/2 and common mode rejection ratio >150 in the band from DC to 100 Hz. We introduce a background suppression figure of merit for characterizing the performance of gradiometers. It allows for optimally setting the measurement baseline and for quickly assessing the advantage, if any, of performing a measurement in a gradiometric mode. As an application, we consider the problem of fetal Magnetocardiography (fMCG) detection in the presence of a large background maternal MCG signal.
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characterizing atomic magnetic gradiometers for fetal Magnetocardiography
arXiv: Instrumentation and Detectors, 2019Co-Authors: I A Sulai, Ronald T. Wakai, Zack Deland, Michael D Bulatowicz, C P Wahl, T G WalkerAbstract:Atomic magnetometers (AMs) offer many advantages over superconducting quantum interference devices (SQUIDs) due to, among other things, having comparable sensitivity while not requiring cryogenics. One of the major limitations of AMs is the challenge of configuring them as gradiometers. We report the development of a spin-exchange relaxation free (SERF) vector atomic magnetic gradiometer with sensitivity of $3\, \rm{fT} \,{cm}^{-1}{Hz}^{-1/2}$ and common mode rejection ratio (CMRR) $> 150$ in the band from DC to 100 Hz. We introduce a background suppression figure of merit for characterizing the performance of gradiometers. It allows for optimally setting the measurement baseline, and for quickly assessing the advantage, if any, of performing a measurement in gradiometric mode. As an application, we consider the problem of fetal Magnetocardiography (fMCG) detection in the presence of a large background maternal MCG signal.
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Magnetocardiography with a modular spin exchange relaxation free atomic magnetometer array
Physics in Medicine and Biology, 2012Co-Authors: R. Wyllie, Ronald T. Wakai, M Kauer, G S Smetana, T G WalkerAbstract:We present a portable four-channel atomic magnetometer array operating in the spin-exchange relaxation-free regime. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically foetal Magnetocardiography, such as a compact modular design and fibre-coupled lasers. The modular design allows the independent positioning and orientation of each magnetometer. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms. These measurements were taken with a 6-11 fT Hz(-1/2) single-channel baseline sensitivity that is consistent with the independently measured noise level of the magnetically shielded room.
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Magnetocardiography with a modular spin exchange relaxation free atomic magnetometer array
arXiv: Medical Physics, 2011Co-Authors: R. Wyllie, Ronald T. Wakai, M Kauer, G S Smetana, T G WalkerAbstract:We present a portable four-channel atomic magnetometer array operating in the spin exchange relaxation-free regime. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically foetal Magnetocardiography, such as a compact modular design, and fibre coupled lasers. The modular design allows the independent positioning and orientation of each magnetometer, in principle allowing for non-planar array geometries. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms. These measurements were taken with a 6-11 fT Hz^(-1/2) single-channel baseline sensitivity that is consistent with the independently measured noise level of the magnetically shielded room.
R. Wyllie - One of the best experts on this subject based on the ideXlab platform.
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Optical magnetometer array for fetal Magnetocardiography
Optics Letters, 2012Co-Authors: R. Wyllie, Ronald T. Wakai, Matthew Kauer, Thad WalkerAbstract:We describe an array of spin-exchange-relaxation-free optical magnetometers designed for detection of fetal Magnetocardiography (fMCG). The individual magnetometers are configured with a small volume with intense optical pumping, surrounded by a large pump-free region. Spin-polarized atoms that diffuse out of the optical pumping region precess in the ambient magnetic field and are detected by a probe laser. Four such magnetometers, at the corners of a 7 cm square, are configured for gradiometry by feeding back the output of one magnetometer to a field coil to null uniform magnetic field noise at frequencies up to 200 Hz. We present the first measurements of fMCG signals using an atomic magnetometer.
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Magnetocardiography with a modular spin exchange relaxation free atomic magnetometer array
Physics in Medicine and Biology, 2012Co-Authors: R. Wyllie, Ronald T. Wakai, M Kauer, G S Smetana, T G WalkerAbstract:We present a portable four-channel atomic magnetometer array operating in the spin-exchange relaxation-free regime. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically foetal Magnetocardiography, such as a compact modular design and fibre-coupled lasers. The modular design allows the independent positioning and orientation of each magnetometer. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms. These measurements were taken with a 6-11 fT Hz(-1/2) single-channel baseline sensitivity that is consistent with the independently measured noise level of the magnetically shielded room.
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Magnetocardiography with a modular spin exchange relaxation free atomic magnetometer array
arXiv: Medical Physics, 2011Co-Authors: R. Wyllie, Ronald T. Wakai, M Kauer, G S Smetana, T G WalkerAbstract:We present a portable four-channel atomic magnetometer array operating in the spin exchange relaxation-free regime. The magnetometer array has several design features intended to maximize its suitability for biomagnetic measurement, specifically foetal Magnetocardiography, such as a compact modular design, and fibre coupled lasers. The modular design allows the independent positioning and orientation of each magnetometer, in principle allowing for non-planar array geometries. Using this array in a magnetically shielded room, we acquire adult magnetocadiograms. These measurements were taken with a 6-11 fT Hz^(-1/2) single-channel baseline sensitivity that is consistent with the independently measured noise level of the magnetically shielded room.
Janette F. Strasburger - One of the best experts on this subject based on the ideXlab platform.
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dynamics of the use of Magnetocardiography in the study of the cardiac conduction system of the chick embryo
Birth defects research, 2020Co-Authors: Michael A Schellpfeffer, Janette F. Strasburger, Sarah Strand, W J Lutter, Oswaldo Baffa, Tan Phan, Ronald T. WakaiAbstract: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. Different examination chambers were tested to optimize embryonic thermal stability and magnetic signal acquisition. All examinations were done with magnetic shielding. The OPM sensors were placed next to the egg shell. The embryo's position was localized by transilluminating the intact egg or ultrasound imaging the egg with an open air cell to optimize sensor placement. The raw data for each embryo was postprocessed to obtain a fMCG composite waveform. Results fMCG's were obtained in embryos from Day #12 to 19. The best success with intact eggs was obtained using five sensors; one at the bottom and four around the lower perimeter of the egg at 90° intervals with the egg oriented vertically and the air cell up. Using ultrasound imaging with the air cell open only two sensors were necessary, one at the bottom and one laterally next to the embryo. fMCGs were analyzed for heart rate and rhythm, each portion of the PQRST waveform, and the PR interval, QRS complex, RR interval, and QT interval. Conclusions This study validates the chick embryo as an animal model to study in a longitudinal and noninvasive fashion the fetal cardiac conduction system by using OPM Magnetocardiography.
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fetal diagnosis of kcnq1 variant long qt syndrome using fetal echocardiography and Magnetocardiography
Pacing and Clinical Electrophysiology, 2020Co-Authors: Lajja Desai, Janette F. Strasburger, Nina L Gotteiner, Ron Wakai, Sabrina Tsao, Angira PatelAbstract:A pregnant woman with KCNQ1 variant long QT syndrome (LQTS) underwent fetal Magnetocardiography (fMCG) after atrioventricular (AV) block was noted during fetal echocardiogram-atypical for LQTS type 1. Concern for fetal LQTS on fMCG prompted monitoring of maternal labs, change of maternal beta blocker therapy, and frequent fetal echocardiograms. Collaboration between obstetricians, neonatologists, and pediatric cardiologists ensured safe delivery. Beta blocker therapy was initiated after birth, and postnatal evaluation confirmed genotype and phenotype positive LQTS in the infant. Our experience suggests diagnosis and evaluation of fetal LQTS can alter antenatal management to reduce risk of poor fetal and postnatal outcomes.
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low cost fetal Magnetocardiography a comparison of superconducting quantum interference device and optically pumped magnetometers
Journal of the American Heart Association, 2019Co-Authors: Sarah Strand, Vishal Shah, Janette F. Strasburger, W J Lutter, Oswaldo Baffa, Ronald T. WakaiAbstract: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 a...
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in utero diagnosis of long qt syndrome by Magnetocardiography
Circulation, 2013Co-Authors: Bettina F. Cuneo, Janette F. Strasburger, Akihiko Kandori, Hitoshi Horigome, Takayoshi Hosono, Ronald T. WakaiAbstract:Background—The electrophysiology of long QT syndrome (LQTS) in utero is virtually unstudied. Our goal here was to evaluate the efficacy of fetal Magnetocardiography (fMCG) for diagnosis and prognosis of fetuses at risk of LQTS. Methods and Results—We reviewed the pre/postnatal medical records of 30 fetuses referred for fMCG because of a family history of LQTS (n=17); neonatal/childhood sudden cardiac death (n=3), or presentation of prenatal LQTS rhythms (n=12): 2° atrioventricular block, ventricular tachycardia, heart rate < 3rd percentile. We evaluated heart rate and reactivity, cardiac time intervals, T-wave characteristics, and initiation/termination of Torsade de Pointes, and compared these with neonatal ECG findings. After birth, subjects were tested for LQTS mutations. Based on accepted clinical criteria, 21 subjects (70%; 9 KCNQ1, 5 KCNH2, 2 SCN5A, 2 other, 3 untested) had LQTS. Using a threshold of corrected QT= 490 ms, fMCG accurately identified LQTS fetuses with 89% (24/27) sensitivity and 89% (...
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assessment of left ventricular pre ejection period in the fetus using simultaneous Magnetocardiography and echocardiography
Fetal Diagnosis and Therapy, 2010Co-Authors: Nana Aba Mensahbrown, Ronald T. Wakai, Bageshree Cheulkar, Shardha Srinivasan, Janette F. StrasburgerAbstract:Introduction: Fetal Magnetocardiography (fMCG) is a promising new technique for assessing fetal rhythm; however, no prior studies have utilized fMCG to evaluate human fetal electromechanical physiology. Pre-ejection period (PEP) is an important measure of the electromechanical activation of the heart, and is altered by disease states and arrhythmias. Materials and Methods: A novel technique was used to assess fetal PEP and its relationship to other fetal systolic time intervals, RR interval, and gestational age (GA). 25 normal human fetuses between 19 and 38 weeks’ gestation were studied using simultaneous pulsed Doppler ultrasound and fMCG. Correlations among PEP, ejection time, QRS width and RR interval were assessed using linear regression. Results: Across all subjects, PEP was found to correlate with GA (R = 0.57, p Conclusion: PEP exhibits developmental trends that provide a better understanding of the normal development of the human fetal heart.
Hitoshi Horigome - One of the best experts on this subject based on the ideXlab platform.
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successful trans maternal nadolol pharmacotherapy in a fetus presenting with long qt syndrome type 2 complicated by torsade de pointes
Journal of Cardiology Cases, 2020Co-Authors: Yuriko Shima, Hitoshi Horigome, Lisheng Lin, Yoshihiro Nozaki, Takashi Murakami, Takumi Ishiodori, Yusuke Yano, Miho Takahashi, Hiro Yamasaki, Hidetoshi TakadaAbstract:Fetuses with congenital long QT syndrome (LQTS) may experience life-threatening arrhythmias, such as torsade de pointes (TdP), and/or functional atrioventricular block. However, trans-maternal pharmacotherapy for these cases is rarely reported and management practices have yet to be established. The fetus of a mother with genetically-confirmed LQTS type 2 (LQT2) presented with complex arrhythmias, diagnosed via Magnetocardiography as ventricular arrhythmias (including TdP), at 28 weeks of gestation. After initiation of trans-maternal nadolol administration at 15 mg/d initial dosage and 30 mg/d subsequent dosage, the frequency of fetal ventricular arrhythmias decreased and almost disappeared within several days. The mother gave birth to the baby at full term without significant complications in either the mother or fetus. This is the first report that demonstrates the efficacy and safety of trans-maternal administration of nadolol for treatment of symptomatic LQT2 fetuses with TdP. .
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Prenatal Diagnosis of Atrioventricular Block and QT Interval Prolongation by Fetal Magnetocardiography in a Fetus with Trisomy 18 and SCN5A R1193Q Variant
Hindawi Limited, 2017Co-Authors: Lisheng Lin, Hiromi Hamada, Miho Takahashi-igari, Yoshiaki Kato, Yoshihiro Nozaki, Mana Obata, Hitoshi HorigomeAbstract:We report a case of fetal trisomy 18 with SCN5A R1193Q variant that presented with sinus bradycardia, 2 : 1 atrioventricular block (AVB), and QT interval prolongation. These complex arrhythmias were diagnosed by fetal Magnetocardiography combined with ultrasound findings. Advanced AVB and ventricular arrhythmias were confirmed after birth. Genetic testing of the baby revealed a SCN5A R1193Q variant, which we considered could account for the various arrhythmias in this case
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in utero diagnosis of long qt syndrome by Magnetocardiography
Circulation, 2013Co-Authors: Bettina F. Cuneo, Janette F. Strasburger, Akihiko Kandori, Hitoshi Horigome, Takayoshi Hosono, Ronald T. WakaiAbstract:Background—The electrophysiology of long QT syndrome (LQTS) in utero is virtually unstudied. Our goal here was to evaluate the efficacy of fetal Magnetocardiography (fMCG) for diagnosis and prognosis of fetuses at risk of LQTS. Methods and Results—We reviewed the pre/postnatal medical records of 30 fetuses referred for fMCG because of a family history of LQTS (n=17); neonatal/childhood sudden cardiac death (n=3), or presentation of prenatal LQTS rhythms (n=12): 2° atrioventricular block, ventricular tachycardia, heart rate < 3rd percentile. We evaluated heart rate and reactivity, cardiac time intervals, T-wave characteristics, and initiation/termination of Torsade de Pointes, and compared these with neonatal ECG findings. After birth, subjects were tested for LQTS mutations. Based on accepted clinical criteria, 21 subjects (70%; 9 KCNQ1, 5 KCNH2, 2 SCN5A, 2 other, 3 untested) had LQTS. Using a threshold of corrected QT= 490 ms, fMCG accurately identified LQTS fetuses with 89% (24/27) sensitivity and 89% (...
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successful management of supraventricular tachycardia in a fetus using fetal Magnetocardiography
Fetal Diagnosis and Therapy, 2005Co-Authors: Kanako Abe, Hiromi Hamada, Yangjen Chen, Azusa Abe, Hideki Watanabe, Yutaka Fujiki, Hiroyuki Yoshikawa, Takashi Murakami, Hitoshi HorigomeAbstract:We report a fetus at 33 weeks of gestation with supraventricular tachycardia, which was successfully managed by transplacental administration of an antiarrhythmic agent. Fetal Magnetocardiography (fMCG) revealed supraventricular tachycardia of the long RP' tachycardia type. Transplacental administration of sotalol, instead of digoxin, was selected as the first-line drug, and it successfully converted supraventricular tachycardia to sinus rhythm. The diagnosis of the type of supraventricular tachycardia was confirmed by electrocardiography after birth. Sotalol was also effective after birth to maintain sinus rhythm. This case demonstrates that fMCG is potentially useful for prenatal differentiation of the type of supraventricular tachycardia and for prenatal treatment of fetal tachyarrhythmias.
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prenatal diagnosis of long qt syndrome using fetal Magnetocardiography
Prenatal Diagnosis, 1999Co-Authors: Hiromi Hamada, Akihiko Kandori, Hitoshi Horigome, Mitsuhiro Asaka, Sadahiko Shigemitsu, Toshio Mitsui, Takeshi Kubo, Keiji TsukadaAbstract:We describe the detection of congenital long QT syndrome in a fetus at 37 weeks' gestation using Magnetocardiography (MCG). The prenatal diagnosis was confirmed by standard electrocardiography (ECG) performed after birth. This is the first case report of fetal long QT syndrome detected by MCG. Fetal MCG may be useful in the prenatal diagnosis of congenital cardiac disease with abnormal ECG findings.