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1.
J Am Heart Assoc ; 11(15): e025224, 2022 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-35904205

RESUMO

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. We compared referral diagnosis and treatment with fMCG diagnosis using a rating scale and restricted our review to the 144 subjects from the tachycardia, bradycardia/AV block, and familial long QT syndrome categories. Additional fMCG findings beyond those of the referring echocardiogram, or an alternative diagnosis were seen in 117/144 (81%), and 81 (56%) were critical changes. Eight (5.5%) had resolution of arrhythmia before fMCG. At least moderate changes in management were seen in 109/144 (76%) fetuses, of which 35/144 (24%) were major. The most diverse fMCG presentation was long QT syndrome, present in all 3 referral categories. Four of 5 stillbirths were seen with long QT syndrome. Nine fetuses showed torsades de pointes ventricular tachycardia, of which only 2 were recognized before fMCG. Conclusions FMCG has a significant impact on prenatal diagnosis and management of arrhythmias or familial arrhythmia risk, which cannot be fully met by existing technology. The combination of fMCG and fetal echocardiography in fetal care centers will be needed in the future to optimize care.


Assuntos
Síndrome do QT Longo , Magnetocardiografia , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/terapia , Eletrocardiografia/métodos , Feminino , Feto , Humanos , Síndrome do QT Longo/diagnóstico , Magnetocardiografia/métodos , Gravidez , Diagnóstico Pré-Natal/métodos , Medição de Risco
2.
Ann Noninvasive Electrocardiol ; 26(6): e12879, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34250679

RESUMO

BACKGROUND: The magnetocardiography (MCG) functional localization can transfer the biomagnetic signal to the electrical activity information inside the heart. The electrical activity is directly related to the physiological function of the heart. METHODS: This study proposes a practical method for MCG functional localization based on the boundary element method (BEM) and the Nelder-Mead (NM) simplex algorithm. Single equivalent moving current dipole (SEMCD) is served as the equivalent cardiac source. The parameters of SEMCD are adapted using the NM simplex algorithm by fitting the measured MCG with the calculated MCG obtained based on BEM. The SEMCD parameters are solved in the sense that the difference between measured and calculated MCG is minimized. RESULTS: The factors affecting the localization accuracy of this BEM-NM method were first explored with synthetic signals. Then, the results with real MCG signals show a good agreement between the SEMCD location and the region where ventricle depolarization starts, demonstrating the feasibility of this idea. CONCLUSIONS: This is the first three-dimensional localization of the onset of ventricular depolarization with the BEM-NM method. The method is promising in the noninvasive localization of lesions for heart diseases.


Assuntos
Magnetocardiografia , Complexos Ventriculares Prematuros , Adaptação Fisiológica , Algoritmos , Eletrocardiografia , Humanos
3.
Biomed Phys Eng Express ; 7(2)2021 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-33578399

RESUMO

The aim of this paper is to present the use of a portable, unshielded magnetocardiograph (MCG) and identify key characteristics of MCG scans that could be used in future studies to identify parameters that are sensitive to cardiac pathology. We recruited 50 patients with confirmed myocardial infarction (MI) within the past 12 weeks and 46 volunteers with no history of cardiac disease. A set of 38 parameters were extracted from MCG features including both signals from the sensor array and from magnetic images obtained from the device and principal component analysis was used to concentrate the information contained in these parameters into uncorrelated predictors. Linear fits of these parameters were then used to examine the ability of MCG to distinguish between sub-groups of patients. In the first instance, the primary aim of this study was to ensure that MCG has a basic ability to separate a highly polarised patient group (young controls from post infarction patients) and to identify parameters that could be used in future studies to build a formal diagnostic tool kit. Parameters that parameterised left ventricular ejection fraction (LVEF) were identified and an example is presented to show differential low and high ejection fractions.


Assuntos
Cardiopatias , Magnetocardiografia , Infarto do Miocárdio , Humanos , Magnetocardiografia/métodos , Infarto do Miocárdio/diagnóstico , Volume Sistólico , Função Ventricular Esquerda
4.
Emerg Med J ; 38(1): 47-52, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33051274

RESUMO

BACKGROUND: We aimed to estimate the diagnostic accuracy of the VitalScan magnetocardiograph (MCG) for suspected acute coronary syndrome (ACS). METHODS: We undertook a prospective cohort study evaluating the diagnostic accuracy of the MCG in adults with suspected ACS. The reference standard of ACS was determined by an independent adjudication committee based on 30-day investigations and events. The cohort was split into a training sample, to derive the MCG algorithm and an algorithm combining MCG with a modified Manchester Acute Coronary Syndrome (MACS) clinical probability score, and a validation sample, to estimate diagnostic accuracy. RESULTS: We recruited 756 participants and analysed data from 680 (293 training, 387 validation), of whom 96 (14%) had ACS. In the training sample, the respective area under the receiver operating characteristic (AUROC) curves were the following: MCG 0.66 (95% CI 0.58 to 0.74), MACS 0.64 (95% CI 0.54 to 0.73) and MCG+MACS 0.70 (95% CI 0.63 to 0.77). MCG specificity was 0.16 (95% CI 0.12 to 0.21) at the threshold achieving acceptable sensitivity for rule-out (>0.98). In the validation sample (n=387), the respective AUROCs were the following: MCG 0.56 (95% CI 0.48 to 0.64), MACS 0.69 (95% CI 0.61 to 0.77) and MCG+MACS 0.64 (95% CI 0.56 to 0.72). MCG sensitivity was 0.89 (95% CI 0.77 to 0.95) and specificity 0.15 (95% CI 0.12 to 0.20) at the rule-out threshold. MCG+MACS sensitivity was 0.85 (95% CI 0.73 to 0.92) and specificity 0.30 (95% CI 0.25 to 0.35). CONCLUSION: The VitalScan MCG is currently unable to accurately rule out ACS and is not yet ready for use in clinical practice. Further developmental research is required.


Assuntos
Síndrome Coronariana Aguda/diagnóstico , Magnetocardiografia , Adulto , Idoso , Algoritmos , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade
5.
Physiol Meas ; 41(12): 125003, 2021 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-33086201

RESUMO

OBJECTIVE: Fetal magnetocardiography (fMCG) is a non-invasive biomagnetic technique that provides detailed beat-to-beat fetal heart rate analysis, both in normal rhythm as well as in fetal arrhythmias. New cryogenic-free sensors called optically pumped magnetometers (OPMs) have emerged as a less expensive and more geometrically flexible alternative to traditional Superconducting Quantum Interference Device (SQUID) technology for performing fMCG. The objective of the study was to show the ability of OPMs to record fMCG using flexible geometry while seeking to preserve signal quality, and to quantify fetal heart rate variability (FHRV). APPROACH: Biomagnetic measurements were performed with OPMs in 24 healthy pregnant women with uncomplicated singleton pregnancies between 28 and 38 weeks gestation (GA). A total of 96 recordings were analyzed from OPM data that was collected using sensors placed in two different maternal configurations over the abdomen. The fMCG signals were extracted and the quality of the recordings were quantified by peak amplitudes and signal-to-noise ratio (SNR). R peaks were used to perform both time and frequency domain FHRV analysis. FHRV measures obtained from OPMs were compared descriptively to the same measures obtained from GA-matched existing SQUID data. MAIN RESULTS: The fMCG derived from OPMs were observed in 21 of the 24 participants. Higher detection rates (85%) of fMCG signals were observed in the data sets recorded at GA >32 weeks. Peak amplitudes and SNR values were similar between two maternal configurations, but peak amplitudes were significantly higher (p = 0.013) in late GA compared to early GA. FHRV indicators were successfully extracted and their values overlapped substantially with those obtained from SQUID recordings. SIGNIFICANCE: Taking advantage of the geometric flexibility of the OPMs, we have demonstrated their ability to record and quantify fMCG in different maternal positions as opposed to rigid SQUID configurations.


Assuntos
Frequência Cardíaca Fetal , Magnetocardiografia , Adolescente , Adulto , Arritmias Cardíacas , Feminino , Idade Gestacional , Humanos , Masculino , Gravidez , Razão Sinal-Ruído , Adulto Jovem
6.
Clin Hemorheol Microcirc ; 78(3): 227-236, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33337351

RESUMO

BACKGROUD: Patients with chest pain and suspected of coronary artery disease(CAD) need further test to confirm the diagnosis. Magnetocardiography (MCG) is a non-invasive and emission-free technology which can detect and measure the weak magnetic fields created by the electrical activity of the heart. OBJECTIVE: This study aimed to investigate the usefulness of the 10 MCG parameters to detect CAD in patients with chest pain by means of a machine learning method of multilayer perceptron(MLP) neural network. METHODS: 209 patients who were suffering from chest pain and suspected of CAD were enrolled in this cross-sectional study. In all patients, 12-lead electrocardiography(ECG) and MCG test were performed before percutaneous coronary angiography(PCA). 10 MCG parameters were analyzed by MLP neural networks. RESULTS: 11 diagnostic models(M1 to M11) were established after MLP analysis. The accuracies ranged from 71.2% to 90.5%. Two models(M10 and M11) were further analyzed. The accuracy, sensitivity, specificity, PPV, NPV, PLR and NLR were 89.5%, 89.8%, 88.9%, 92.7%, 84.7%, 11.10 and 0.11, of M10, and were 90.0%, 91.4%, 87.7%, 92.1%, 86.6%, 7.43 and 0.10, of M11. CONCLUSIONS: By a method of MLP neural network, MCG is applicable in identifying CAD in patients with chest pain, which seems beneficial for detection of CAD.


Assuntos
Doença da Artéria Coronariana , Magnetocardiografia , Dor no Peito/diagnóstico por imagem , Angiografia Coronária , Doença da Artéria Coronariana/complicações , Doença da Artéria Coronariana/diagnóstico por imagem , Estudos Transversais , Eletrocardiografia , Humanos , Aprendizado de Máquina , Estudos Prospectivos
7.
Physiol Meas ; 42(1): 015006, 2021 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-33147578

RESUMO

OBJECTIVE: Fetal heart rate variability (HRV) is widely used for monitoring fetal developmental disturbances. Only expensive fetal magnetocardiography (fMCG) allows the precise recording of the individual fetal heart beat intervals uncovering also highly frequent vagal modulation. In contrast, transabdominal fetal electrocardiography (fECG) suffers from noise overlaying the fetal cardiac signal. Cardiotocography (CTG) is the clinical method of choice, however, based on Doppler ultrasound, improper to resolve single beats concisely. The present work addresses the transferability of established electrophysiological HRV indices to CTG recordings during the fetal maturation period of 20-40 weeks of gestation (WGA). APPROACH: We compared (a) HRV indices obtained from fMCG, CTG and fECG of short-term amplitude fluctuations (sAMPs) and long-term amplitude fluctuations (lAMPs) and complexity, and (b) their diagnostic value for identifying maturational age, fetal growth restriction (FGR) and small for gestational age (SGA). We used the functional brain age score (fABAS) and categories of long- and short-term regulation and complexity. MAIN RESULTS: Integrating all substudies, we found: (a) indices related to long-term regulation, and with modified meaning and values of short-term regulation and sympathovagal balance (SVB) according to electrophysiological HRV standards can be obtained from CTG. (b) Models using HRV indices calculated from CTG allow the identification of maturational age and discriminate FGR from controls with almost similar precision as electrophysiological means. (c) A modified set of HRV parameters containing short- and long-term regulation and long-term/short-term ratio appeared to be most suitable to describe autonomic developmental state when CTG data is used. SIGNIFICANCE: Whereas the predominantly vagally modulated beat-to-beat precise high frequencies of HRV are not assessable from CTG, we identified relevant related HRV indices and categories for CTG recordings with diagnostic potential. They require further evaluation and confirmation with respect to any issues of fetal developmental and perinatal problems in subsequent studies. This methodology significantly extends the measures of established CTG devices. Novelty and significance HRV indices provide predestinated diagnostic markers of autonomic control in fetuses. However, the established CTG does not provide the temporal precision of electrophysiological recordings. Beat-to-beat related, mainly vagally modulated behavior is not exactly represented in CTG. However, a set of CTG-specific HRV indices that are mainly comparable to established electrophysiological HRV parameters obtained by magnetocardiography or electrocardiography provided almost similar predictive value for fetal maturational age and were helpful in characterizing FGR. These results require validation in the monitoring of further fetal developmental disturbances. We recommend a corresponding extension of CTG methodology.


Assuntos
Cardiotocografia , Eletrocardiografia , Frequência Cardíaca Fetal , Magnetocardiografia , Diagnóstico Pré-Natal/métodos , Feminino , Humanos , Gravidez
8.
Circ J ; 84(12): 2166-2174, 2020 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-33162489

RESUMO

BACKGROUND: Approximately one-third of patients with advanced heart failure (HF) do not respond to cardiac resynchronization therapy (CRT). We investigated whether the left ventricular (LV) conduction pattern on magnetocardiography (MCG) can predict CRT responders.Methods and Results:This retrospective study enrolled 56 patients with advanced HF (mean [±SD] LV ejection fraction [LVEF] 23±8%; QRS duration 145±19 ms) and MCG recorded before CRT. MCG-QRS current arrow maps were classified as multidirectional (MDC; n=28) or unidirectional (UDC; n=28) conduction based on a change of either ≥35° or <35°, respectively, in the direction of the maximal current arrow after the QRS peak. Baseline New York Heart Association functional class and LVEF were comparable between the 2 groups, but QRS duration was longer and the presence of complete left bundle branch block and LV dyssynchrony was higher in the UDC than MDC group. Six months after CRT, 30 patients were defined as responders, with significantly more in the UDC than MDC group (89% vs. 14%, respectively; P<0.001). Over a 5-year follow-up, Kaplan-Meyer analysis showed that adverse cardiac events (death or implantation of an LV assist device) were less frequently observed in the UDC than MDC group (6/28 vs. 15/28, respectively; P=0.027). Multivariate analysis revealed that UDC on MCG was the most significant predictor of CRT response (odds ratio 69.8; 95% confidence interval 13.14-669.32; P<0.001). CONCLUSIONS: Preoperative non-invasive MCG may predict the CRT response and long-term outcome after CRT.


Assuntos
Terapia de Ressincronização Cardíaca , Insuficiência Cardíaca , Magnetocardiografia , Insuficiência Cardíaca/diagnóstico por imagem , Insuficiência Cardíaca/terapia , Humanos , Estudos Retrospectivos , Volume Sistólico , Resultado do Tratamento
9.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1803-1806, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018349

RESUMO

Fetal magnetocardiography (fMCG) is a noninvasive method of measuring magnetic signals generated by the depolarizing heart. fMCG has proved to have superior signal-to-noise ratio characteristics and enables precise detection of the R-R intervals for fetal heart rate variability (FHRV) analysis. FHRV is one of the most useful clinical indicators for investigating fetal neurodevelopment. Currently, fMCG recordings rely on superconducting quantum interference devices (SQUIDs) which require cryogenics leading to a high cost device. New cryogenic-free sensors called optical pump magnetometers (OPMs) have emerged as alternative to SQUIDs. To take advantage of the flexibility of the OPM sensors, we explored the ability of OPM sensors to measure the fMCG at different maternal positions and sensor locations. Data were collected with a 14-channel OPM array using different sitting positions (mother leaning forward, backward, and prone). Projection operator algorithm based on minimum norm (POMN) was applied to extracted fMCG. R peaks were obtained to perform standard FHRV analysis. We were able to configure a standalone array of the OPMs that conforms to the shape of the maternal abdomen to obtain signals with sufficient quality. We extracted and quantified FHRV parameters in three low-risk fetuses. Results showed that FHRV values are in the range of previous SQUID studies.


Assuntos
Magnetocardiografia , Algoritmos , Feminino , Feto , Humanos , Projetos Piloto , Gravidez , Razão Sinal-Ruído
10.
Birth Defects Res ; 112(20): 1825-1833, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32790153

RESUMO

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.


Assuntos
Magnetocardiografia , Animais , Arritmias Cardíacas/diagnóstico , Embrião de Galinha , Galinhas , Feto , Humanos
11.
Fetal Diagn Ther ; 47(9): 711-716, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32615554

RESUMO

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. CASE PRESENTATIONS: We identified 3 cases of clinically suspected LQTS based on fetal echocardiogram (2 had sinus bradycardia, 1 had second-degree atrioventricular block with negative maternal anti-SSA/SSB antibody titers). With institutional review board approval, these patients were prospectively enrolled for fECG acquisition. Offline post-processing generated fECG waveforms and calculated QT intervals. Case 1 and 3 had a maternal history of LQTS. Two of the three fetuses with suspected LQTS had confirmed LQTS by postnatal ECG and genetic testing. FECG was able to identify a prolonged corrected QT interval in both cases. One of these also had fetal magnetocardiography (fMCG), which yielded similar findings to the fECG. The third fetus had a normal fECG; fMCG and postnatal ECG were also normal. CONCLUSIONS: In 3 cases, fECG findings corroborated the diagnosis of LQTS. Noninvasive fECG may offer a novel method for fECG that is portable and more clinically accessible.


Assuntos
Eletrocardiografia/métodos , Coração Fetal/fisiopatologia , Síndrome do QT Longo/diagnóstico por imagem , Magnetocardiografia/métodos , Adulto , Feminino , Frequência Cardíaca Fetal/fisiologia , Humanos , Síndrome do QT Longo/fisiopatologia , Gravidez , Cuidado Pré-Natal , Diagnóstico Pré-Natal , Adulto Jovem
12.
Circ Arrhythm Electrophysiol ; 13(5): e008082, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32421437

RESUMO

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.


Assuntos
Coração Fetal/fisiopatologia , Frequência Cardíaca Fetal , Síndrome do QT Longo/diagnóstico , Magnetocardiografia , Diagnóstico Pré-Natal/métodos , Natimorto , Causas de Morte , Bases de Dados Factuais , Feminino , Predisposição Genética para Doença , Idade Gestacional , Hereditariedade , Humanos , Síndrome do QT Longo/genética , Síndrome do QT Longo/mortalidade , Síndrome do QT Longo/fisiopatologia , Mutação , Fenótipo , Valor Preditivo dos Testes , Gravidez , Medição de Risco , Fatores de Risco
13.
Pacing Clin Electrophysiol ; 43(4): 430-433, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32168391

RESUMO

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.


Assuntos
Ecocardiografia , Síndrome do QT Longo/diagnóstico , Magnetocardiografia , Diagnóstico Pré-Natal/métodos , Adulto , Feminino , Humanos , Canal de Potássio KCNQ1/genética , Síndrome do QT Longo/genética , Gravidez
14.
Proc Natl Acad Sci U S A ; 117(9): 4942-4947, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32071237

RESUMO

A spectroscopic paradigm has been developed that allows the magnetic field emissions generated by the electrical activity in the human body to be imaged in real time. The growing significance of imaging modalities in biology is evident by the almost exponential increase of their use in research, from the molecular to the ecological level. The method of analysis described here allows totally noninvasive imaging of muscular activity (heart, somatic musculature). Such imaging can be obtained without additional methodological steps such as the use of contrast media.


Assuntos
Técnicas e Procedimentos Diagnósticos , Músculos/diagnóstico por imagem , Músculos/metabolismo , Encéfalo/diagnóstico por imagem , Coração/diagnóstico por imagem , Humanos , Magnetocardiografia/métodos , Magnetoencefalografia/métodos , Modelos Teóricos , Mialgia/diagnóstico por imagem , Miografia/métodos , Análise Espectral/métodos
15.
J Neurosci Methods ; 336: 108620, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-32057772

RESUMO

BACKGROUND: A frequency dependent subtraction method, SUBTR, is developed to remove maternal and fetal magnetocardiography (mMCG and fMCG) interference from fetal magnetoencephalography (fMEG). But channels close to fetal head cannot be used as references for SUBTR in order to protect fMEG from subtraction and this results in cardiac residual when these channels have important fMCG frequency components. Cardiac residual creates noise in evoked response (ER) which results in poor ER detection. NEW METHOD: We developed an enhanced SUBTR algorithm, which we call SUBTR with minimum norm projection operator (SUBTRwMNPO), by employing covariance based minimum norm projection operators (MNPO). mMCG and fMCG signals are extracted from the raw data using MNPO and they are subtracted in the frequency domain from raw data to extract fetal Evoked Response (fER). RESULTS: When tested on 87 datasets, SUBTRwMNPO is shown to attenuate cardiac interference almost totally resulting in a clean fER signal. COMPARISON WITH EXISTING METHODS: Cardiac attenuation with SUBTRwMNPO is either as good as or better than SUBTR. SUBTRwMNPO has higher attenuation rate for the datasets where SUBTR leaves cardiac residual. CONCLUSIONS: SUBTRwMNPO is successful in removing cardiac interference regardless of the orientation of fMCG and fMEG signal spaces. It can also be used to remove cardiac interference when there is no prior knowledge of fetal head location.


Assuntos
Magnetocardiografia , Magnetoencefalografia , Algoritmos , Feminino , Feto , Humanos , Técnica de Subtração
16.
Circ Arrhythm Electrophysiol ; 13(1): e007273, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31937120

RESUMO

BACKGROUND: Atrial fibrillation ablation-related atrial tachycardia (AT) is complex and may demonstrate several forms: anatomic macroreentrant AT (AMAT), non-AMAT, and focal AT. We aimed to elucidate the recurrence rate and mechanisms of atrial fibrillation ablation-related AT recurrence. METHODS: Among 147 patients with ATs treated with the Rhythmia system, 68 (46.3%) had recurrence at mean 4.2 (2.9-11.6) months, and 44 patients received a redo procedure. AT circuits in the first procedure were compared with those in the redo procedure. RESULTS: Although mappable ATs were not observed in 7 patients, 68 ATs were observed in 37 patients during the first procedure: perimitral flutter (PMF) in 26 patients, roof-dependent macroreentrant AT (RMAT) in 18, peritricuspid flutter in 10, non-AMAT in 14, and focal AT in 3. During the redo AT ablation procedure, 54 ATs were observed in 41/44 patients: PMF in 24, RMAT in 14, peritricuspid flutter in 1, non-AMAT in 14, and focal AT in 1. Recurrence of PMF and RMAT was observed in 15 of 26 (57.7%) and 8 of 18 (44.4%) patients, respectively, while peritricuspid flutter did not recur. Neither the same focal AT nor the same non-AMAT were observed except in 1 case with septal scar-related biatrial AT. Epicardial structure-related ATs were involved in 18 of 24 (75.0%) patients in PMF, 4 of 14 (28.6%) in RMAT, and 4 of 14 (28.6%) in non-AMAT. Of 21 patients with a circuit including epicardial structures, 6 patients treated with ethanol infusion in the vein of Marshall did not show any AT recurrence, although 8 of 15 (53.3%) treated with radiofrequency showed AT recurrence (P=0.04). CONCLUSIONS: Although high-resolution mapping may lead to correct diagnosis and appropriate ablation in the first procedure, the recurrence rate is still high. The main mechanism of atrial fibrillation ablation-related AT is the recurrence of PMF and RMAT or non-AMAT different from the first procedure. Epicardial structures (eg, coronary sinus/vein of Marshall system) are often involved, and ethanol infusion in the vein of Marshall may be an additional treatment.


Assuntos
Fibrilação Atrial/diagnóstico por imagem , Fibrilação Atrial/cirurgia , Flutter Atrial/diagnóstico por imagem , Ablação por Cateter/efeitos adversos , Magnetocardiografia/métodos , Distribuição por Idade , Idoso , Análise de Variância , Flutter Atrial/epidemiologia , Flutter Atrial/cirurgia , Mapeamento Potencial de Superfície Corporal/métodos , Ablação por Cateter/métodos , Estudos de Coortes , Bases de Dados Factuais , Feminino , Seguimentos , Humanos , Incidência , Magnetocardiografia/efeitos adversos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/diagnóstico por imagem , Complicações Pós-Operatórias/epidemiologia , Recidiva , Reoperação/métodos , Medição de Risco , Índice de Gravidade de Doença , Distribuição por Sexo , Fatores de Tempo
17.
Ann Noninvasive Electrocardiol ; 25(4): e12741, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-31955494

RESUMO

BACKGROUND: The early repolarization pattern (ERP) in electrocardiography (ECG) has been considered as a risk for ventricular fibrillation (VF), but effective methods for identification of malignant ERP are still required. We investigated whether high spatiotemporal resolution 64-channel magnetocardiography (MCG) would enable distinction between benign and malignant ERPs. METHODS: Among all 2,636 subjects who received MCG in our facility, we identified 116 subjects (43 ± 18 years old, 54% male) with inferior and/or lateral ERP in ECG and without structural heart disease, including 13 survivors of VF (ERP-VF(+)) and 103 with no history of VF (ERP-VF(-)). We measured the following MCG parameters in a time-domain waveform of relative current magnitude: (a) QRS duration (MCG-QRSD), (b) root-mean-square of the last 40 ms (MCG-RMS40), and (c) low amplitude (<10% of maximal) signal duration (MCG-LAS). RESULTS: Compared to ERP-VF(-), ERP-VF(+) subjects presented a significantly longer MCG-QRS (108 ± 24 vs. 91 ± 23 ms, p = .02) and lower MCG-RMS40 (0.10 ± 0.08 vs. 0.25 ± 0.20, p = .01) but no difference in MCG-LAS (38 ± 22 vs. 29 ± 23 ms, p = .17). MCG-QRSD and MCG-RMS40 showed significantly larger area under the ROC curve compared to J-peak amplitude in ECG (0.72 and 0.71 vs. 0.50; p = .04 and 0.03). The sensitivity, specificity, and odds ratio for identifying VF(+) based on MCG-QRSD ≥ 100 ms and MCG-RMS40 ≤ 0.24 were 69%, 74%, and 6.33 (95% CI, 1.80-22.3), and 92%, 48%, and 10.9 (95% CI, 1.37-86.8), respectively. CONCLUSION: Magnetocardiography is an effective tool to distinguish malignant and benign ERPs.


Assuntos
Magnetocardiografia/métodos , Fibrilação Ventricular/diagnóstico , Fibrilação Ventricular/fisiopatologia , Adulto , Feminino , Humanos , Masculino
18.
Ann Noninvasive Electrocardiol ; 25(3): e12715, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31587426

RESUMO

BACKGROUND: Identification of coronary ischemia in patients presenting with chronic chest pain is difficult as resting ECG can be normal. Diagnosis of coronary ischemia requires evaluation during exercise or pharmacological stress. A noninvasive test to identify coronary ischemia at rest without the need for exercise is desirable. We studied the diagnostic accuracy of magnetocardiography (MCG) at rest to detect coronary ischemia in these patients. METHODS: Patients with chronic chest pain and suspected coronary ischemia with a normal ECG were included. Patients underwent treadmill test (TMT) and were divided into TMT positive and TMT negative groups. MCG was recorded in a magnetically shielded room. Iso-field contour maps generated at the T-wave peak were compared between the groups. From the magnetic field map (MFM), the magnetic field angle at T-wave peak was calculated and was also compared across the two groups. RESULTS: There were a total of 29 patients, 12 with positive TMT and 17 with negative TMT. An abnormal magnetic field angle was more common in the TMT positive group (72% vs. 6%). Abnormal contour maps in the form of nondipole patterns or abnormal orientation were seen in 81.8% (9/11) patients in TMT positive group and 6.8% (1/17) patients in the TMT negative group (p < .001). CONCLUSION: Abnormal magnetic field angle and abnormal magnetic field maps in MCG recorded at rest are able to identify the presence of coronary ischemia in patients with chronic chest pain and a normal resting ECG.


Assuntos
Dor no Peito/etiologia , Doença da Artéria Coronariana/complicações , Doença da Artéria Coronariana/diagnóstico , Eletrocardiografia/métodos , Magnetocardiografia/métodos , Isquemia Miocárdica/complicações , Isquemia Miocárdica/diagnóstico , Dor no Peito/fisiopatologia , Doença da Artéria Coronariana/fisiopatologia , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/fisiopatologia , Estudos Prospectivos , Sensibilidade e Especificidade
19.
J Med Eng Technol ; 43(7): 401-410, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31738627

RESUMO

The electrical impulses of the heart will generate a tiny magnetic field outside the thorax that is measured as Magnetocardiographic signals. The challenging study is to estimate the cardiac activities in terms of depolarisation and repolarization maps from the measured signals called as inverse problem. This is computed only if one has solved generic or subject- specific prior models using the anatomical structures of the myocardium, the torso and the detectors called as forward problem. In this study, the Discretised heart is priorily assumed as the dipolar sources forming a double layer. The thorax structure modelled with finite element meshes is considered in the forward study. The magnetocardiographic data are simulated using uniform double layer model representing transmembrane distribution on the epicardium and endocardium. Using this data, the activation maps are non-invasively imaged on the heart surface using Tikhonov's regularisation technique. The inverse study is extended to reconstruct the depolarisation sequences of the abnormal cases.


Assuntos
Coração/fisiologia , Magnetocardiografia , Modelos Cardiovasculares , Análise de Elementos Finitos , Humanos , Masculino , Infarto do Miocárdio/fisiopatologia , Tórax/fisiologia
20.
JACC Clin Electrophysiol ; 5(10): 1144-1157, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31648739

RESUMO

OBJECTIVES: This study aimed to develop a novel premature ventricular contraction (PVC) mapping method to predict PVC origins in whole ventricles by merging a magnetocardiography (MCG) image with a cardiac computed tomography (CT) image. BACKGROUND: MCG can noninvasively discriminate PVCs originating from the aortic sinus cusp from those originating from the right ventricular outflow tract. METHODS: This study was composed of 22 candidates referred for catheter ablation of idiopathic PVCs. MCG and CT were performed the same day before ablation. Estimated origins by MCG-CT imaging using the recursive null steering spatial filter algorithm were compared with origins determined by electroanatomic mapping (CARTO, Biosense Webster, Inc., Diamond Bar, California) during the ablation procedure. Radiopaque acrylic markers for the CT scan and coil markers generating a weak magnetic field during MCG measurements were used as reference markers to merge the 2 images 3-dimensionally. RESULTS: PVC origins were determined by endocardial and epicardial mapping and ablation results in 18 (86%) patients (right ventricular outflow tract in 10 patients, aortic sinus cusp in 2 patients, interventricular septum in 1 patient, near His bundle in 1 patient, right ventricular free wall in 1 patient, and left ventricular free wall in 3 patients). Estimated origins by MCG-CT imaging matched the origins determined during the procedure in 94% (17 of 18) of patients, whereas the electrocardiography algorithms were accurate in only 56% (10 of 18). Discrimination of an epicardium versus an endocardium or right- versus left-sided septum was successful in 3 of 4 patients (75%). CONCLUSIONS: The diagnostic accuracy of noninvasive MCG-CT mapping was high enough to allow clinical use to predict the site of PVC origins in the whole ventricles.


Assuntos
Magnetocardiografia , Tomografia Computadorizada por Raios X , Complexos Ventriculares Prematuros/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Bloqueio de Ramo/fisiopatologia , Ablação por Cateter , Feminino , Ventrículos do Coração/fisiopatologia , Humanos , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Imagem Multimodal , Seio Aórtico/fisiopatologia , Resultado do Tratamento , Complexos Ventriculares Prematuros/fisiopatologia , Complexos Ventriculares Prematuros/cirurgia
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